Northern Eclipse Help Reference

Glossary


 

A - E

 

 

A/D Conversion

Analog to digital conversion of a continuous electrical signal (e.g. Video) to a set of discrete numeric values. Frame grabbers convert analog video signals to digital images.

Accelerator Processor

A hardware processor in a digital image processing system that is exclusively devoted to image processing tasks; typically based on a dedicated microprocessor.

Active Window

The image window that is currently selected. If only one image window is open, it will be the active window. In multi-open image window instances, the active window is always the front most window  (non active Windows have gray title bars in Northern Eclipse© ).

Adaptive Thresholding

A method of binary contrast enhancement where the threshold value changes throughout an image based on local brightness char­acteristics.

Additive Color

The form of color creation based on the additive mixing of the red, green, and blue pri­mary colors.

AGC

Automatic Gain Control. In video detectors an AGC is built in to automatically adjust the dynamic range to varying lighting conditions. The AGC should be turned off for most computer imaging applications.

Airy Disk

Diffraction pattern created by an object under the microscope.  Rings of bright/dark pattern may be seen around small objects at high magnification.  The Rayleigh Criterion is one way to describe the limit of resolution of the microscope.  This criterion describes the amount of overlap of neighboring Airy disks - when the two Airy disks merge the object can no longer be resolved.

Aliasing          

The formation of objects, or "edges", within an image that do not exist within the original sample.  Caused by image sampling errors in digital systems.

Analog Image Processing

The technique of process­ing images while they are in the form of a continuous electrical signal, typically a video signal.

Analog Signal Reconstruction

The recreation of a continuous analog electrical signal (typically a video signal) from a series of discrete digital brightness values.

Analog-to-digital Converter (A/D)

A semi-conduc­tor device that converts an analog voltage level (repre­senting image brightness) to a digital quantity.

Analogue-to-Digital (A/D) Converter

An electrical device used to covert analogue signals to digital signals.

Angstrom (Å)

A unit of length 1/10th of a nanometer (10-10 meters).

Area

The selected area (selected region) is the area of an image in which image processing is applied to or objects are counted and measured. Note that the time required to complete these tasks is dependent on the size of the area, the complexity of the selection and the number of Data Options requested. To improve processing efficiency one should define the smallest possible Data Setup Options and use a single rectangular selection.

Area of Interest

"Area of Interest", also known as ROI (Region of Interest), or selection. A connected subset of pixels defined within an image which may be arranged in any shape using Northern Eclipse’s© tools for drawing areas of interest within an image. They are used to segregate the subset from the rest of the image.

Aspect Ratio

The ratio of an image's horizontal to vertical dimensions, generally stated as x:y.

Background Subtraction

Due to non-uniformity in illumination, a process called background subtraction is often used in image analysis to reduce these effects. This can be performed in real time prior to image analysis on a real time frame grabber, or after acquisition with a standard frame grabber. Background Subtraction is possible in Northern Eclipse using the Looping function for incoming digital or analog images or can be applied to static images using Boolean Operations.

Bandwidth

Analog: Bandwidth is the range of frequencies transmitted from a given signal. Digital: The total amount of Data transmittable within a fixed time period.

Beam Splitter

A prism, or partial mirror, that diverts part or all of the light from one direction to another.  A beam splitter is often used to divert some or all of the light from the eyepieces to the camera.

Bilinear Interpolation

A form of pixel interpolation that is based on a weighted average of the four pixels surrounding the pixel location of interest.

Binary Image

An image comprised of only black and white pixels.

Binary Morphological Process

The morphological process intended to operate on a binary image. Neighborhood black and white pixel patterns are evaluated.

Binning

Binning can have a number of meanings in image analysis. In Northern Eclipse©  binning is referred to as a method of including or excluding objects either by area, perimeter, shape factor or any of a number of morphometric parameters. Digital camera companies refer to binning as a method of joining information from several pixels to a single pixel. Many of the high quality digital cameras can do this joining of pixel information (binning) during the image transfer to a computer. This form of binning allows greater camera sensitivity at the expense of resolution.

Bit

This is the smallest unit in a binary number (binary digit), or the smallest unit of digital information recognized by a computer and may take the value of either zero or one ( TRUE or FALSE, ON or OFF, 0 or 1, BLACK or WHITE, etc.). A pixel is represented by one or more computer bits. The sum of bits per pixel directly determines the number of colors or gray levels that can be represented. An 8-bit (1byte) image contains 28 or 256 gray levels, usually from zero (black) to 255 (white).  Note: many image processing programs consider zero = white and 256 = black.

Bit Depth

The number of gray levels that can be represented in each pixel of an image  (e.g. 8 bit = 256 gray levels, 10 bit = 1024 gray levels, 12 bit = 4096 gray levels, 16 bit = 65536 gray levels).

Bit Map

A 2D array used to depict an image. Each block in the array contains a value that describes a sample of the image in terms of its color.

Bit Plane

The view of a single bit of an image.  A bit­ plane represents the on or off level of a particular bit's contribution to each pixel's brightness.

Bits per Pixel

The same as Bit Depth. Describes the "deepness" of an image. Northern Eclipse© can use 8, 16, 24 or 48 Bits per Pixel.

Black Level

The amount of signal offset (alters the blackness level of the image).

Black Level Reference

The reference used by an A/D converter to establish the amplitude of a video signal to be converted to black (0).

BMP

Image bit-mapped format used by Windows and OS/2. This is a very common image format and is universal to most windows imaging software.

Boundary Description

A description of an object's perimeter; typically a series of chain codes or line segments having a length and direction.

Bright Field

Illumination of the specimen where the background appears "bright".  This is the "normal" illumination method in microscopy.  See also: dark field and epi-­illumination.

Brightness

The quantity of light assigned to a pixel in a digital image.  In comparison, intensity refers to the quantity of light actually reflected or transmitted from a physical scene.  Also, one of the three color compo­nents of the HSB color space that controls how bright an HSB color appears.

Brightness Histogram

A graphical representation of the number of pixels in an image at each gray level.

Brightness Slicing

A double binary contrast enhance­ment operation where pixel brightnesses below a lower threshold and above an upper threshold are set to black, while brightnesses between the two thresh­olds are set to white.

Burn In

Prolonged exposure to a bright scene may leave an after image on certain video detectors or monitors. Also a term used to test a new computer.

Byte

A computer term for an information unit of 8 bits.

Calibration (Distance)

Redefinition of the distance scale associated with an image (i.e. distance between pixels in a unit of measure other than pixels), (i.e. using a calibration slide on a microscope and figuring out pixels per micron). See Distance Calibration.

Calibration (Hardware)

Redefinition of Color Map characteristics to compensate for variations in image quality due to hardware differences. Once the calibrations have been determined they can be reused each time a particular type of hardware is used again. You can correct the nonlinearities present between different image acquisition systems as long as you have an image with known intensities.

CCD

This is an abbreviation for Charge Coupled Device. In Northern Eclipse©  CCD is generally used in discussing video cameras that use this device to detect images (i.e. CCD cameras).

CCD & CID

Types of electronic cameras using electronic chips as the detector.  CCD = charge-coupled device, CID = charge-induced device.  Both cameras use a chip with a detector array which is "read" by electronic circuitry.

CCIR (PAL)

European TV standard (756H x 581V pixels). Set by the Comite Consultatif International des Radio Communication.

CCIR Monochrome

The European monochrome standard video format originally used by commercial television broadcasters and still used in monochrome video cameras.

CD "Burner"

A device for writing information to CD-ROM disks.  The files can then be readily read by a regular CD-ROM drive.

CD-ROM

A laser disk storage device (Compact Disk - Read Only Memory).  Blank CD-ROM disks (which are very cheap) can be loaded with computer files using a CD-ROM "burner".  The disk can be written to many times (multi-session), but the existing data cannot be erased.  However, take care - the existing data may be made "unreadable" if an error occurs during a subsequent "bum" to the same multi-session disk.  Currently CD-ROM disks can hold 650 Mbyte of data.  The laser "etching" method of writing to a disk results in a very stable method of long term storage of valuable data.

CD-RW

Re-writable CD laser disk, having the same capacity as the CD-ROM (650 Mbyte) but can be written/erased many times.  The CD-RW disk can be read using the CD-ROM drive present in most computers.

Center of Mass

The (x,y) balance point of an object where there is equal mass above, below, left, and right. (center of gravity).

Centroid

The geometric center of an object.  It is equivalent to the Center of Mass.  This is found by calculating the average X (or horizontal) and Y (or vertical) coordinate values for every pixel  in a given object .

Charge Coupled Device (CCD)

A semiconductor photodetector device used in most video cameras.

Closing

A binary or gray scale morphological opera­tion composed of a dilation operation followed by an erosion operation; small holes and gaps are filled, while objects tend to remain their original size. See Binary Operations.

C-mount

Standard screw-in lens mount for the attachment of a camera to a microscope.

CMY

Cyan, Magenta, Yellow - 3 color subtractive color representation most useful for image printing. Many dye sublimation printers use CMY in their print process.

CMYK

Cyan, Magenta, Yellow, Black - 4 color process with improved black and therefore better image contrast than CMY. Used in the printing industry for full-color printing.

Collector Lens

A lens with a light source used to provide a suitably sized area of illumination.

Color Compression

The compression of color images, typically first converting the image to a less redundant color space such as hue, saturation, and brightness.

Color Correction

The changes made to a color image to improve the perceived deficiencies in color, brightness and contrast. See Equalize.

Color Decoder

A circuit that breaks down a compos­ite color video signal into a component form for digitization, typically from NTSC or PAL to  RGB.

Color Encoder

A circuit that combines the parts of a component color video signal into a composite form for display, typically from  RGB to NTSC or PAL.

Color Features

Features of an object that relate to its color characteristics, such as hue and saturation.

Color Histogram

Generally three histograms - one for each color component - representing the number of pixels in an image at each level.

Color Look Up Table (LUT)

See LUT and Color Maps.

Color Maps

Often referred to as a LUT (look up table).  The digital image is comprised of pixels, which have been assigned gray level values.  These gray level values by default are represented by entry 0 being black up through entry 255 being white. Using a LUT other colors can be assigned to represent any or all of the gray level entries. In Northern Eclipse© Color Maps have the suffix (.map). See Apply Color Map.

Color Resolution

Like brightness resolution but applied to each color component. The accuracy at which an image's pixels are quantized is measured in number of bits or gray levels.

Color Saturation

Color saturation refers to the degree of color present (i.e. intensity of color).

Color Space

A representation of color controlled by a number of color components, such as RGB or HSV.  Also, the range of colors that can be created by mix­ing a set of primary colors in differing proportions.

Color Temperature

A measure of the bluish (high temperature) or reddish (low temperature) hue of the "white" light expressed as the absolute temperature (degrees Kelvin).  This nomenclature is used to express both the sensitivity of an electronic light detector and the color display of a computer monitor.

Composite Color

A video signal composed of a single physical signal, into which is encoded both lumi­nance and chrominance information.

Compression

Mathematical technique allowing images to be stored using less space.  In Northern Eclipse©  the TGA image format does automatic image compression and the JPEG plugin allows for user defined image compression.

Contrast

Perceived as the sharpness of an image.  High contrast images have a larger difference between white and black or in the case of color images, the color range is greater.  As contrast is increased the color (gray level) spreads out. In Northern Eclipse©  viewing an image with the histogram tool and then applying the proper equalization values will show great improvements in image contrast.

Contrast (camera)       

The visibility of an object against the background.  A low-contrast feature blends into the background, and a high-contrast feature stands out distinctly.  Contrast can be manipulated by altering the gain and blackness level on a camera.

Contrast Enhancement

The enhancement of the brightness attributes of an image.

Contrast Stretch

A digital imaging function which stretches the collected image between 0 (black) and 256 (white) to make maximum use of the available gray scale range available (256 shades of gray in an 8-bit image and 0 to 65535 in a 16-bit image).

Control Points

Multiple points (fiducial markers) placed on an image to control a warping transformation; the points repre­sent the before and after locations of the transformation. Also, points on drawn selected regions that can be used to change the shape or size of a region.

Convolution

A neighborhood arithmetic operation performed for each pixel in the image.  The size and numerical coefficients for the neighborhood are defined by a kernel, which is passed over the image one pixel at a time.  The coefficients are multiplied with the underlying gray levels and added together, with the normalized result replacing the value of the pixel at the origin (typically at the center of the neighborhood).  Convolutions can be used for sharpening, edge detection, smoothing, and object separation. See Convolution Filters.

Convolution Coefficient

One of several weights used in the weighted average computation of the spatial convolution process.

Convolution Mask

The set of convolution coeffi­cients used in the spatial convolution process.

Cooled CCD

A CCD camera that operates below ambient temperature to reduce or eliminate dark current "noise".

Current Window

The image window that is currently selected. If only one image window is open, it will be the active window.  In multi-open image window instances, the currently active window is always the front most window (non active Windows have gray title bars in Northern Eclipse© ).

Cursor

The cursor, or pointer, is a symbol that represents where on the screen the mouse is currently located.  This symbol will change its shape when the system is in different modes or  when the cursor is over different parts of the screen.  Northern Eclipse©  has many different cursor styles during various operations.

Cyan, Magenta, and Yellow Color Space (CMY)

A color representation used in the printing industry based on subtracting the primary colors (red, green, and blue) from white - which is the same as adding the secondary colors cyan, magenta, and yellow to black - to create the desired color.

Dark Current

The background current produced by a photodetector.  Cooling a CCD detector significantly reduces the dark current "noise"(s).

Dark Field

Oblique illumination is used to produce a dark background with reflective structures brightly lit against it.  Useful for observing live unstained cells.

Decompression

The recreation of an original image from a compressed form of the image.

Deconvolution

A mathematical process used to remove out-of-­focus blur from digitized optical sections. It is a restoration operation where a pre­vious optical or other process such as image blur­ring due to misfocus, is reversed. Typically a stack of images is deconvolved. Northern Eclipse has a deconvolution plugin for No Neighbour (2D), Nearest Neighbour, and Full Iterative using the point spread function (PSF) method.

Depth of Field

The range of distances between imaged object and lens where the object will appear in focus.

Depth of Focus

The range of distances between lens and photosensor where the imaged object will appear in focus.

Device Driver

The lowest level of software in a digi­tal image processing system.  A device driver inter­faces the function library to physical devices such as frame grabbers, accelerator processors, and special­ purpose processors. Digital cameras and framegrabbers require software device drivers.

Difference Image

The image resulting from the pixel-by-pixel subtraction of one image from another.

Differencing

An operation that subtracts one image from another, pixel by pixel.  Typically, each image is of the same scene but acquired at different times or under different lighting conditions.

Digital

Digital data can be handled without error; manipulation of analogue data (or signals) and will always involve some finite degree of error, however small.

Digital Camera

A camera with digitizing and computer interfacing circuitry.  Since these cameras are designed to be operated through a computer interface, images are transferred directly to the computer. No frame grabber or external digitizing system is required.  Northern Eclipse©  supports a full line of digital cameras.

Digital Image

An image composed of discrete pixels, each having an associated brightness value.

Digital Image Processing

The technique of process­ing images while they are in the form of discrete dig­ital brightness quantities.

Digital to Analog Converter (D/A)

A semiconduc­tor device that converts digital image brightness quantities to analog voltage levels.

Digitization Sampling and Quantizing

An analog video signal to create a digital image.

Dilate Filter

Number of Repetitions - Selects the number of iterations of dilation to carry out.

Dilation

A binary or gray scale morphological opera­tion that increases the size of bright objects uniformly in relation to the background; small holes and gaps are filled. See Binary Operations.

Distance

This measurement quantity is the straight-line distance between the two points selected. If a spatial calibration has been made, the quantity is reported in calibrated units.

DLL

Windows Dynamic Link Library.  A file that contains executable code, providing increased functionality for the programs that use them.

Dot Pitch

The size of the color phosphor dots in a color cathode-ray tube.

DPI

Dots per Inch, a term common to printer manuals.  The higher the DPI, the greater the resolution.

DVD Disk

Very high capacity laser disk (10x the capacity of a CD-ROM).  There are currently several formats and standards for DVD disks.

Dye Saturation

Refers to the highest level of light that can be used to produce fluorescence - further increase in the laser light will not increase the level of fluorescence.

Dynamic Range

Range of values of a measured variable over which a system provides accurate data (e.g. an 8 bit image has a dynamic range of 0 to 255, 16 bit image has a dynamic range of 0 to 65,535).

Dynamic Range (or Bit Depth)

The number of different shades of gray between black and white that are present in the image.  An 8-bit image has 256 gray levels, a 12-bit image has 4096 gray levels and a 16-bit image has 65,536 gray levels.

Dynamic Range (or Brightness)

The brightness span of an image's gray scale.

Edge Enhancement

An algorithm for sharpening the edges on stored digital images.

Edge Enhancement Filter

A spatial filter that increases the edge detail in an image.

Edge Filter

Another term for a shortpass or longpass filter with a very sharp cut-on or cut-off.

Empty Magnification

Greater magnification than the useful magnification.  No useful information will be obtained and sharpness and contrast will decrease.

Epi-fluorescence         

Fluorescence technique where the excitation light passes through the objective before reaching the specimen. It therefore also acts as a condenser.  Conventional fluorescence microscopy on modem microscopes is normally performed with epi-illumination.

Equalization

Use this command to re-map the currently active image’s histogram.  For example an image that has a gray level range of 10 to 50, (a very low contrast image), may be stretched out from 0 to 255 (10 mapping to 0, ..., 50 mapping to 255).  This operation will maximize the contrast of an image.  Note that linear re-mapping of an image made by this command will irretrievably alter the image.(NOT TO BE USED IN CONJUNCTION WITH DENSITOMETRY)

Erode Filter

Number of Erosions - Select the number of iterations of erosion to carry out.  Numbers larger than 1 are useful if you have an image that you are certain will require a large amount of erosion.

Erosion

A binary or gray scale morphological opera­tion that uniformly reduces the size of bright objects in relation to the background; small speckle and spurs are eliminated. See Binary Operations

Even Field

The even numbered lines in an interlaced scan video signal.

 

 

F - J

 

 

False Color

Color added to the image by using a Look Up Table (LUT).  The color is often in the form of a color gradient that will enhance small differences in the displayed image. See Apply Colormap

Fast Fourier Transform (FFT)

An algorithmically faster version of the discrete Fourier transform. See FFT Plugin.

Feature Extraction

The second step of image analysis that seeks to measure the individual features of an object.

Feature Measure

A particular measure that describes some aspect of an object.

File Format

The method used to store an image to disk.  Northern Eclipse©  uses BMP, TIFF, TGA, SPE and JPEG  file formats to save images and loads BMP, TIFF, TGA, SPE, JPEG, Biorad PIC, IMG, and free format. See Load Image.

File Interchange Format

A standardized image data format that provides portability of digital images between digital image processing systems.

Filter Wheel

Computer controlled device used to select one of a number of filters.  Typically located between the lamp housing and microscope.

Flat Shading

A method of three-dimensional model shading, where surfaces are shaded with a constant shade value based on model fighting conditions.

Focus  

The ability of a lens to converge light rays to a single point.  A high quality color corrected lens will result in all wavelengths being focused to a single point.  The size of the "point" is determined by the NA of the lens and the wavelength of light (diffraction limited microscopy).

Fourier Space

A space containing the Fourier transform information of the object.  The back focal plane of the objective is a Fourier space.

Fourier Transformation (FFT)

The separation of an image into its spatial or frequency components.  The Fourier transform image can be filtered and manipulated to alter or reduce periodic signals within the image, and then an inverse transform function performed to regain the original image (with selected frequencies accentuated or removed). See FFT Plugin.

Fourier Transform

A frequency transform that decomposes a spatial image into a set of sinusoidal frequency component functions.

Frame Buffer

Temporary storage area for an image. In Northern Eclipse© all frame buffers are in computer memory, and not on the frame grabber.

Frame Grabber

This may also be called a video digitizing board.  It is a computer board that digitizes an image.  The source of the image may be from any one of a number of different types of cameras or devices (e.g. VCR) that produce a compatible signal (in the US, NTSC-170 is the normal format, and in Europe, PAL is the normal format) for digitization. The boards that Northern Eclipse© uses can optionally accept NTSC, RGB, Y/C, and PAL signals.

Frame Grabber Board

A computer peripheral providing the acquisition, storage, and display of digital images.

Frame Grabber Device

A memory card used to an image digitally.

Frame Rate

The rate at which video images are digi­tized, processed, or displayed from a digital image processing system.

F-Stop

Ratio of the focal length of a lens to the diameter of the lens.

Gain (analog)  

The level of signal amplification. It alters the whiteness level of the image.  Used in conjunction with the offset control (or black level) to produce an image with the best contrast.

Gain (digital)

The value by which every pixel in an image is multiplied in a histogram stretching operation.

Gamma

The coefficient of a logarithmic function describing the actual brightness ramp of a particular device. Used to describe the relationship between the original signal and the display image.  A gamma of 1 indicates that the relationship is linear.

Geometric Distortion

Spatial distortions caused by inaccuracies in an optical system, such as in a lens.

Geometric Transformation

An operation that trans­forms the geometric characteristics of an image to a new form, such as a rotation or scaling.

GIF      

Graphics Interchange Format is the file format commonly used to display indexed-color graphics and images in hypertext markup language (HTML) documents over the World Wide Web and other online services.  GIF is an LZW-compressed format designed to minimize file size and electronic transfer time.

Gigabyte (GB or Gbyte)

1,073,741,824 (230) bytes.  The capacity of a hard drive is usually denoted in number of GB storage capacity.

Gray Image

An image in which multiple values, not just the black and white of a binary image, are permitted for each pixel.

Gray Level

This is the scale that is used to represent monochrome images.  Northern Eclipse©  can use 8 or 16 bit gray scale images directly. All other bit depths are promoted up to the next supported size.

Gray Levels

Digital images can be stored as either 8-bit (256 levels of gray) or 16-bit (65,596 levels of gray).  A 24-bit color image contains 256 levels (8-bit) for each of the 3 primary colors, red, green and blue.

Gray Scale

Gray Scale pixel values represent a level of grayness or brightness, ranging from completely black to completely white.  This class is sometimes referred to as “monochrome.”  In an 8-bit Gray Scale image, a pixel with a value of 0 is completely black, and a pixel with a value of 255 is completely white.  A value of 127 represents a gray color exactly halfway between black and white (medium-gray), and a pixel value of 64 has a gray color halfway between medium-gray and black. Although Gray Scale images with bit depths of 2, 4, 6 and 12 do exist, 8 BIT Gray Scale images are the most common format in use, and are used by the most popular monochrome image formats (e.g. TIFF, BMP). Intensity values are represented with 8-bit integers, which provides 256 (0 - 255) levels of gray. 16 bit images are now becoming commonplace with the advent of digital cameras.

Gray Scale (Brightness Levels)

The number of gray levels available to represent the brightnesses in a digital image.

Gray Scale (Shades of Gray)

The various shades of gray (light intensities) within a digital image. 

Gray Scale Image

An image composed of gray level brightnesses.

Gray Scale Morphological Process

The morpho­logical process intended to operate on a gray scale image; neighborhood minimum and maximum brightness values are evaluated.

High Pass Filter

A spatial filter that accentuates the high frequency detail or attenuates the low fre­quency detail in an image.

Histogram

A line graph of a frequency distribution in which the samples are displayed proportional to the corresponding frequencies. For example the frequency distribution of the intensities in an image.

Histogram (Image Histogram)

A graph that depicts the number of pixels at each gray level within the total image, or within an area of the image that has been marked.  The image histogram can be used to both analyze the distribution of fluorescence within the image and to manipulate the Look Up Table (LUT) levels within the image.

Histogram Stretching

The multiplication by a con­stant value of every pixel brightness in an image, hav­ing the effect of stretching or shrinking the image histogram.

Horizontal Sync

The synchronizing signal in a video signal that conveys the beginning of a line.

Host Computer

The overseeing computer in a digital image processing system, generally responsible for user interface, system coordination, and often image processing activities.

HSV

Hue, Saturation and Value.  Non-linear transformation of RGB which corresponds more closely to the way humans perceive color.

Hue

One of the three color components of the HSB color space that controls the color spectrum from red through the yellows, greens, blues, and violets. 

Hue, Saturation, and Brightness Color Space (HSB)

A color representation based on how humans per­ceive color; generally the best color space in which to carry out color image processing operations.

Hue, Saturation, and Intensity Color Space (HSI)

Although distinct, an analogous color space to hue, saturation, and brightness.

Hue, Saturation, and Value Color Space (HSL)

Although distinct, an analogous color space to hue, saturation, and brightness.

Hue, Saturation, and Value Color Space (HSV)

Although distinct, an analogous color space to hue, saturation, and brightness.

Hz (Hertz)

Cycles per second.

Icon

Symbolic picture that represents a menu tool, function or item.

Image

In regard to Image Analysis, an image is a digital representation of a scene.  It is this digital representation that is used to make measurements.  This digital representation may be digitized from a video camera, a VCR, a scanner, etc.  The image is represented by an NxM grid where each pixel (picture element) in the grid is assigned a value within its dynamic range.

Image Acquisition

The digitization and storage of a digital image.

Image Analysis

The processing and data reduction operation yielding numerical data from an image.

Image Analysis

Performing measurements on features in a stored image without changing the image itself.

Image Analysis

The processing of an image to extract quantitative object measurements and then classify the results.

Image Archive

The long-term storage of a digital image.

Image Class

The category of the image.  The categories are according to the bit depth of an image. Northern Eclipse©  supports Palette(8-bit),Gray Scale(8 & 16-bit) and True Color(24-bit), floating point and 48 bit color images.

Image Combination

Any operation that combines two or more images, pixel by pixel, using a combi­nation function into a resulting image, such as dif­ferencing or spectral ratioing.

Image Compositing

An operation that cuts an object from one image and places it into another image, using a mask image to control the cut and placement processes.

Image Compression

The reduction of digital image data size by removing forms of data redundancy from the raw image data.

Image Enhancement

The processing of an image to improve its visual qualities using known or unknown attributes of the image degradation.

Image Mask

A small reference image of an object of interest used in a matched filtering operation.

Image Processing

Altering the image to improve contrast, sharpness, etc.

Image Restoration

The processing of an image to improve its visual qualities, always using known attributes of the image degradation.

Image Segmentation

The partitioning of a digital image into non-overlapping regions according to gray levels, texture etc.

Image Segmentation

The first step of image analysis that seeks to simplify an image to its basic component elements, or objects.  Image segmentation tasks are composed of image preprocessing, initial object dis­crimination, and object boundary cleanup.

Image Store

The hardware memory array that pro­vides working image storage for a digital image to be acquired, processed, and displayed.

Image Thresholding

Replacement of specified gray levels with a solid area of color (or black or white).  Used to define areas of related intensity level. In Northern Eclipse a color overlay is applied to the image while thresholding and can be extracted using copy plane to get the threshold plane (or binary image).

Image Window

A window created in Northern Eclipse©  used to hold an image for display.

Initial Object Discrimination

The second step in image segmentation, where objects are grossly sepa­rated into groups of similar attributes.

Input Image

An image that is processed in a digital image processing operation.

Intensity

The quantity of light actually reflected or transmitted from a physical scene.  In comparison, brightness refers to the quantity of light assigned to a pixel in a digital image.

Interlace

Scanning pattern in video systems where scan lines from two half frames alternate, such that visual observation of this video display is not affected by flicker.

Inverse Filtering

A restoration operation where a pre­vious optical, or other process such as image blurring due to misfocus, is reversed.

JPG (JPEG)

The Joint Photographic Experts Group (JPEG) format is commonly used to display photographs and other continuous-tone images in hypertext markup language (HTML) documents over the World Wide Web and other online services.  Unlike the GIF format, JPEG retains all color information in an RGB image but compresses file size by selectively discarding data.  A JPEG image is automatically decompressed when opened.  A higher level of compression results in lower image quality.

 

 

K - O

 

 

Kernel

The group of input image pixels used in the spatial convolution process.

Kilobyte (KB or Kbyte)

1024 (210) bytes.

Kirsch Edge Enhancement

A directional spatial edge enhancement filter that increases an image's edge detail in a particular direction.

Koehler Illumination

A system of illumination for a light optical microscope that leads to highly uniform illumination of the field of view and exactly defined conditions for the transillumination of the object. Because half the resolution on a microscope is related to the numerical aperture N.A. of the condenser, proper illumination will give higher resolution.

Laplacian Edge Enhancement

An omnidirectional spatial edge enhancement filter that increases an image's edge detail.

Laplacian Filter

A convolution applied to digitized image.  The resulting modification of the image being an enhancement of all edges.

Lens

The optical element of a camera.  A lens focuses light, projecting it upon a photodetecting device.

Line

The y-axis coordinate of a digital image; a line of pixels traverses an image horizontally.

Linear Process

The process of summing elements (such as pixel brightnesses) multiplied by constant weights (such as convolution coefficients).

Liquid Crystal Display (LCD)

A solid state image display device used in many video display monitors.

Look-up Table (LUT)

See Color Map.

Look-Up Table (LUT)

A hardware or software implementation of a pixel point process mapping function.  For every possible input pixel brightness, a corresponding output brightness is stored in the look­up table.

Lossless Compression

A form of image compression where the data content of the original image is pre­cisely preserved.

Lossy Compression

A form of image compression where the precise data content of the original image is not preserved; rather, the quality is maintained at some arbitrary level.

Low Contrast Image

An image comprised of midrange gray tones with little or no black or white in the image. 

Low Pass Filter

A spatial filter that attenuates the high frequency detail or accentuates the low fre­quency detail in an image.

LUT     

See Look Up Tables.

Magnification  

An image that is the result of an enlarged view of the object.  An increase in image size beyond the resolution of the microscope will result in a larger image, without any increase in resolution (see "empty magnification").  Historically the "magnification", denoted for example as 1000x was displayed along with the image.  However, a more accurate method of displaying the magnification is to use a scale bar within the image.  In this way changes in “magnification" due to the size at which the image is printed or displayed do not affect the denoted scale of the image.

Major Axis

The endpoints of the longest line that can be drawn through an object.

Mask Image

In compositing operations, the image used to cut an object from one image.  A complemented mask image is then used to cut a hole in a destination image where the object is placed.

Median Filter

Image processing method that has the property of smoothing the image while maintaining edges.  This method has a tendency to create "false" edges in the image and so should be used with care.

Median Filter

A nonlinear spatial filter based on the median brightness value of each input group of pix­els; good for removing noise spikes and other single ­pixel anomalies.

Megabyte (MB or Mbyte)

1,048,576 (230) bytes.  The main memory of a computer is currently in the range of MB  (i.e. 64, 128, 256, 512 MB etc.).

Minor Axis

The endpoints of the longest line that can be drawn through an object while maintaining per­pendicularity with the major axis.

Morphometric Parameters

 

Morphological Process

A group process that evalu­ates each pixel in a binary or gray scale image along with its neighboring pixels.  A resulting pixel bright­ness is determined by looking at the input pixel brightness patterns (binary image case) or minimum and maximum values (gray scale image case).

Morphology

Mathematical manipulation of an image using Boolean Operators, standard image manipulation algorithms or non-linear filters to enhance and analyze images.  Each filter acts as a linear filter since each pixels value in the AOI is influenced by its neighboring pixel values.

N.A.

Numerical aperture, typically of a microscope objective, is a measure of the objective's ability to resolve fine detail.

Nanometer (nm)

Unit of length used to measure wavelengths of light. 10-9 meters.  The Kr/Ar laser produces 488 nm (blue), 568 nm (yellow) and 634 nm (red) lines.  Also often used as a unit of measurement in electron microscopy.

ND       

Neutral Density filter blocks light of all wavelengths equally.  Used to attenuate the amount of laser light reaching the sample.

Nearest Neighbor Interpolation 

The simplest form of pixel interpolation using the pixel closest to the pixel location of interest.

Neural Network 

An advanced object classification technique that provides the ability for a classification algorithm to be trained based on actual image examples.

Neutral Density Filter

A gray filter that attenuates light to an equal proportion over the entire visible range.

Neutral Density Filter

A light absorbing filter that reduces the amount of laser light directed at the sample.

Noise

Random fluctuations affecting a signal, they are unrelated to the source being measured and are caused by a variety of conditions.

Non-Image Data 

A set of data that did not originate as an image, such as three-dimensional object models and elevation data.

Non-Interlaced Scan 

In a video signal, a scan where all lines are sequenced in order without any interleave; common to most computer display standard video formats such as SVGA.

Nonlinear Spatial Filter 

A spatial filter that is not based on the process of summing elements (pixel brightnesses) multiplied by constant weights (convolution coefficients), such as the median filter and the morphological process.

Normal Incidence

An angle of incidence of zero degrees.

NTSC

North American TV Standard (768H x 494V pixels). Set by the National Television Systems Committee.

NTSC Composite Color National Television Systems Committee

The color standard video format found in the United States and other countries.

Object

Any element of interest in an image, such as a manufactured part on a conveyor or cell in a biologi­cal specimen; typically in image analysis operations.

Object Classification

The third step of image analy­sis, which seeks to compare the feature measures of an object to known criteria and determine if the object belongs to a particular class of objects.

Objective Image Enhancement

The quantitative enhancement of an image for a degradation using known or measured information about the degrada­tion.

Offset

The brightness value added to every pixel in a histogram sliding operation.

OLE Automation

Object Linking and Embedding Automation enables an application to be externally programmed or customized through a set of predefined rules. In Northern Eclipse©  applications can be written in Visual Basic or Visual C++ to control Northern Eclipse©  externally.  The macro recorder within eclipse can generate programming code for Visual Basic or Visual C++. See the OLE programmers manual for Northern Eclipse© .

Opening

A binary or gray scale morphological opera­tion composed of an erosion operation followed by a dilation operation; small speckle and spurs are removed, while objects tend to remain their original size.

Operation 

A particular digital image processing task, such as edge enhancement, chosen from a fundamen­tal class of operations.

Optical Density

A logarithmic unit of transmission.  OD = log(T).

Optical Image Processing

The technique of pro­cessing images while they are in the optical form.

Optical Resolution

The overall capability of an imag­ing system to resolve spatial details in an imaged scene, not to be confused with spatial density.

Outlining

A binary morphological operation imple­mented by subtracting an eroded version of an image from the original image; object boundaries are high­lighted.

Over Saturation

A situation that occurs when there is too much light for the video camera, causing too high a video signal for the frame grabber.  These analog settings cause the frame grabber to acquire images that have areas too bright to detect the intensity variations within them and then clips these values of those areas to its maximum.  The frame grabber can not distinguish between the intensities of clipped pixels and those of pixels that represent bright areas but are not clipped.

 

 

P - T

 

 

PAL Composite Color Phase Alternation Line

The color standard video format found primarily in European countries.

Palette

A type of image class in which the 256 scale specifies the RGB values associated with an image.  All pixels in an image have an index to the palette. The palette contains the RGB value for the pixel.

PDF     

Portable Document Format is used by Adobe Acrobat, Adobe's electronic publishing software for Windows, Mac OS, UNIX®, and DOS.  You can view PDF files using the Acrobat Reader® software (free software).  PDF files can represent both vector and bitmap graphics, and can contain electronic document search and navigation features such as electronic links. Journals published on the Internet are usually in PDF format.

Periodic Noise

An image noise that appears as bands across an image.

Phase Contrast

Uses the retardation of light by the specimen to produce phase differences, which are converted into contrast.  This technique is used extensively to image unstained live cells. 

Photobleaching          

The destruction of a fluorochrome by light.  The effect of photobleaching is a loss of fluorescence from the area of the sample that has been intensely irradiated with light.  The amount of bleaching is dependent on the fluorescent molecules used (the new Alexa Fluor dyes from molecular probes show very little bleaching), the amount of light used to illuminate the object, and the length of time the sample is irradiated.  Bleaching is an oxidative process, and so the use of antioxidants often reduces photobleaching.

PIC      

File format for Bio-Rad Confocal images, is not the same as other PIC formats.  Can be readily converted to many other formats using Northern Eclipse.

Picture Element

The smallest discrete spatial compo­nent of a digital image.

Pixel

A pixel is the smallest spatially-digitized unit of an image.  A single pixel has a single gray or color value (Derived from ‘picture-element’).

Pixel   

The smallest units by which the image is collected and displayed

Point Spread Function (PSF)

The relationship between an ideal point object and the blurred image obtained from it by conventional microscopy using a high NA objective lens at any chosen focal plane is defined by the image forming characteristics of the objective lens (the three-dimensional "point" formed by the lens).

Prewitt Gradient Edge Enhancement

A directional spatial edge enhancement filter that increases an image's edge detail in a particular direction.

Primary Color

The colors red, green and blue.  These colors are denoted by specific wavelengths within the electromagnetic spectrum and are perceived as separate colors due to the method of light detection in the human eye (the red, green and blue color cones).  Computer screens generate the large range of colors visible by simply mixing the amount of red, green and blue light present at each pixel.

Primary Color

One of three additive colors; red, green and blue, used to create a color of the spectrum.

Process

A mathematically specific technique used to implement a particular digital image processing oper­ation.

Projection       

The process of calculating what a set of serial or optical sections would look like if stacked on top of one another and photographed from different angles.

Pseudo-color

A method of assigning color values to specific gray levels for display purposes (enhances contrast).  Usually used for visual edification to highlight specific gray intensity ranges.

Pseudo-color  

The coloring of a gray scale image by assigning specific gray levels to specific colors or gradients of color using a Color Look Up Table (LUT).  For example the gray scale image collected from FITC fluorescence can be colored with a color gradient of dark green, green, yellow and white to denote the degree of fluorescence intensity.

RAM    

Random Access Memory, the main memory of a computer, the contents of which is lost when the computer is turned off.

Random Access Memory (RAM)

A semiconductor memory device used in image store designs, special ­purpose processors, accelerator processors, and host computers.  RAM devices come in the forms of static RAM (SRAM), dynamic RAM (DRAM), video RAM (VRAM), and dynamic field store memory.

Raster

The form of a video or scanned image where the image is in the form of a series of discrete hori­zontal lines.

Real Image

An image located on the opposite side of the lens from the object that can be projected onto a camera film or the retina of your eye.

Real Time Collection

Fast collection of images showing molecular fluxes (e.g. Ca) or movement of subcellular components within cells.  A small box size combined with a fast scan speed can result in very fast scan rates of several frames per second.  The collected images can be displayed as a time lapse "movie".

Real Time Processing

The ability to carry out a digi­tal image processing operation, or series of opera­tions, on entire images as quickly as new images are available, typically every 1/30th second in the case of a live video source.

Red, Green, and Blue Color Space (RGB)

A color representation used in color image sensors and dis­plays, based on adding the primary colors (red, green, and blue) to black to create the desired color.

Registration Shift

A shift in the apparent position of the specimen when an optical element is inserted or removed.

Rendering

See surface model rendering and volume ren­dering.

Resampling

The alteration of a digital image's sample rate and orientation that occurs with most geometric transformations that involve scaling and rotation.

Resolution

The ability to distinguish between two closely spaced objects on an image.  The resolution of an image analysis system will depend on optical or electronic considerations, depending on which dominates.

Resolution      

The ability of an optical system to distinguish fine detail in a specimen (i.e. the ability to image separately two neighboring points of information).

RGB

A method to display an image using varying amounts of RED, GREEN and BLUE. High quality RGB video cameras have three separate CCD chips for each color and an RGB frame grabber will capture each color separately and then display the picture live in True Color or 24 bits.

RGB    

Red / Green / Blue colors used on the computer screen to generate all other colors.

RGB Component Color

A component color standard video format conveyed as a red signal (R) a green signal (G) and a blue signal (B).

Robinson Edge Enhancement

A directional spatial edge enhancement filter that increases an image's edge detail in a particular direction.

Rotation

A geometric operation that rotates an image about a predetermined point through a desired angle.

RS 170

The North American monochrome standard video format originally used by commercial television broadcasters and still used in monochrome video cameras.

Run Length Coding

A form of lossless image com­pression that looks for sequences of pixels with an identical brightness and codes them into a reduced description.

Sampling

The process of dividing an analog video signal into discrete samples preceding the quantization process.

Saturation

One of the three color components of the HSB color space that controls the purity of a color from a pale to deep color.

Scaling

A geometric operation that enlarges or shrinks the size of an image about a predetermined point.

Segmentation

The process of separating out those parts of an image which are of interest from the background.  See also Image Segmentation.

Shading Correction Equations

Shading correction is generally required for any densitometric measurement. Northern Eclipse© does arithmetic on an image by image basis using Boolean Math, and creates a resultant image rather than fractional transmittance or reflectance values. The resultant image can then be used for densitometric measurements (e.g. Total Gray Values, Average Gray Values, Calibrated Total Gray Values, or Calibrated Average Gray Values).

Transmittance =  Specimen Gray Value - Dark Reference

                                 White Reference  - Dark Reference

Specimen Gray Value = Image Density Measurements will be made on

Dark Reference = Lens cap on camera or Microscope light off

White Reference = Brightest Gray Values (i.e. white field or no slide on the microscope)

Shading Reference Image = White Reference - Dark Reference

Correct Image =  Factor * Specimen Image - Dark Reference + Constant

                                                      Shading Reference Image

The Factor is either maximum possible gray value of the image, or the maximum gray value of the denominator. The Constant value in the numerator is typically zero. It is in the equation for those situations where the Specimen Image may have a lower set of gray values than the Dark Reference Image. The Constant is then used to make the numerator positive.

Shape Factor

When an object has a calibrated perimeter of less than 0.001, the error is too great to allow an accurate measurement of the shape factor and the object is assigned a shape factor of 1.000.  In other words, we assume that a small dot is a circle, not a square.  For very small objects increase the magnification of the microscope or lens system for better imaging results.

Shape Measure

Any measure that describes some aspect of an object's shape characteristics, such as area, perimeter distance, and major axis length.

Sharpen

A crisper image produced by way of a filter resulting in increased differences in gray values of adjacent pixels.

Sharpening image-processing method to "sharpen" the image

This is often useful when producing a slide for presentation, as "blurred" images are particularly distracting for the audience.

Skeletonization

A binary morphological erosion-like operation that reduces objects within an image to a skeleton representation.

Smoothing      

An image-processing method to "smooth" the image.  This often has the effect of blurring the image, but is particularly useful for making "grainy" images look much better.

Sobel

Filter that Northern Eclipse©  uses to extract and accentuate edges and contours in an image by expressing intensity differences between near by pixels as an intensity value. Generally results in smoother, more notable outlines of only the predominant edges of an image.

Sobel Edge Enhancement

An omnidirectional spatial edge enhancement filter that increases an image's edge detail.

Software Application

A computer program used to interact with and implement digital image processing operations.

Spatial Convolution

A group process used to imple­ment a spatial filter.  Each pixel in an image is evalu­ated using its neighboring pixels.  The resulting pixel brightness is calculated as a weighted average of the group of pixels and corresponding convolution coef­ficients.

Spatial Density

The number of pixels in a digital image, not to be confused with optical resolution.

Square Pixel

The case where a pixel has equal dimensions in both the x and y directions.

Standard Video Format

A standardized video signal that conforms to prescribed timing and electrical characteristics.

Stereo Image Pairing

By using two images of the same scene, each taken from a different viewpoint, depth information can be perceived or computed.

Stereology 

A type of image analysis based on the statistical analysis of numbers of objects their size and orientation.

Stokes shift

The difference between the wavelength of excitation and the wavelength of emission of a fluorophore.

Structuring Element

The set of logical values (binary image case) or gray level values (gray scale image case) used in the binary or gray scale morphological process.

Super Video Graphics Array (SVGA)

A group of video display standard video formats created and used by the personal computer industry.

Surface

A component of a three-dimensional model used to create the description of an object.

Surface Model Rendering

Any method used to ren­der a three-dimensional model from a surface description.

S-Video

A component color standard video format conveyed as a luminance signal (Y) and a chrominance signal (C); identical to the Y/C format.

Tag Image File Format (TIFF)

A common digital image file format providing convenient image data archive and transport between computing platforms.

Temporal Noise Reduction

A method of reducing random noise in an image using a multiple image pixel point process to average, pixel by pixel, several identical images where only the noise portion has changed.

Temporal Resolution

The rate at which video images are digitized by a digital image processing sys­tem.

Threshold

A segmentation process that separates regions of interest from background.

Thresholding  

See Image Thresholding.

Thresholding  

Setting all the pixels in a certain range of intensity values to a particular value of color.

TIF      

Tagged-Image File Format is used to exchange files between applications and computer platforms.  TIF is a flexible bitmap image format supported by virtually all paint, image editing, and page-layout applications.  Can be either compressed or uncompressed.

TIFF

Note: Not all TIFF formats are the same. Programs such as Graphic WorkShop (GWS) or HIJAKK  can load and convert most TIFF formats into a file format that is more universal like BMP. Northern Eclipse©  will load most of the common TIFF formats.

Tomography   

Collecting serial sections and reconstructing them to form a 3D image.

Toolbar

A bar containing a row of buttons that perform many of the routine tasks selected rather than using pull-down menus or keystroke combinations. Ubiquitous in Microsoft programs debut for Windows 95/98 and now found in Windows NT and Windows 98 programs.

Top-hat Transformation

A gray scale morphological operation implemented by subtracting an opened version of an image from the original image; bright object peaks are highlighted.

TOTO  

An ultrasensitive green fluorescent nucleic acid stain from molecular probes.  Almost zero fluorescence unless bound to DNA (is approx. 500x more sensitive than Ethidium bromide when bound to DNA).

Transmission Fluorescence

Fluorescence microscopy where the illuminating light is transmitted through the condenser (as in conventional Bright Field microscopy) and the fluorescent light is collected by the objective.  This type of fluorescence microscopy is quite dangerous for the user, as a correctly placed barrier filter is critical for stopping the powerful illuminating light (often UV) from entering the observers eyes.  Transmission fluorescence is now only used in very specialized instruments.

Transmission image

A transmission image of the object can be obtained by collecting the laser light that passes through the condenser.  A very high quality image (with a DIC like look) can be obtained by collecting a very evenly lit low contrast image (many Kalman averages if possible) and then contrast stretching before saving. 

Transmitted light

Light that passes through the specimen.

TRITC (tetramethylrhodamine)

A fluorophore that is readily excited with green/yellow (568 nm) light and emits red fluorescence.  Commonly used in conjunction with FITC for dual labeling.

True Color

24-bit color image class. Each pixel contains 256 shades of red, green and blue, thus each pixel in an image could be any one of 16.7 million colors.

Tube Length

The physical distance between the objective and the eyepiece.

Twain

An industry-standard method for getting scanned pictures into documents, presentations and imaging software. Twain software can be started directly from Northern Eclipse©  and then image will be delivered directly from the scanner (acronym for technology without an interesting name).

 

 

U - Z

 

 

Ultraviolet (UV)

Light from the region of the spectrum with wavelengths between 100 and 400 nm. 

Under-Saturation

When the frame grabber’s analog settings cause it to acquire images that have areas too dark to detect the intensity variations within them, the board clips the values of those areas to zero. The frame grabber board can not distinguish between the intensities of these clipped pixels and those of pixels that represent areas that are dark but are not clipped.

Unsharp Masking Enhancement

A high frequency accentuating filter created by subtracting a low passed image from an original image.

Useful Magnification

The maximum magnification that will give useful information from the specimen.  Usually regarded as 1000 x NA (i.e. 1400 for a 1.4 NA lens).

User Interface

The highest level of software in a digi­tal image processing system providing the look and feel of the system.  The user interface allows the user to view images, control operations, and generally interact with the system.

UV

See Ultraviolet light.

UV Laser

UV lasers are very expensive, but do allow one to use UV excited fluorophores such as Hoechst dyes and Calcium indicators.  Many UV dyes can also be excited using a multi­photon microscope.

Video Camera

An image acquisition device that con­verts an optical image to an electrical video signal (the analog image form).

Video Display Monitor

An image display device that converts an electrical video signal (the analog image form) to an optical form.

Virtual Image

A magnified image located on the same side of the lens as the object.  The image cannot be projected onto film, but can be seen when looking through the lens (for example when looking through a magnifying glass).

Visible Spectrum

Light from the region of the spectrum with wavelengths between 400 nm (blue) and 750 nm (red).

Visualization

The process of "seeing" a three-dimen­sional model.  The model is visualized by rendering it to a form that simulates its natural appearance.

Vital Stain

A dye that is tolerated by living material.  Many fluorescent stains can be used as vital dyes as long as a sufficiently low concentration of the dye is used.  Many dyes are excluded from living cells, but will readily stain dead cells (the basis of the commercially available Live/Dead staining kits).

Volume Element

A three-dimensional version of a pixel.  A volume element is a cube with unit dis­tances of width, height, and depth.

Volume Rendering

Any method used to render a three-dimensional model from a volume description.

Voxel  

A three dimensional pixel (volume element) in a digital image.

Warping Transformation

A geometric operation that contorts an image, often using control points to determine how the resulting image is stretched and shifted.

Water Dipping Objective

An objective designed to be immersed into the culture dish from above (used for microinjection and electrophysiology).

Water Immersion Objective

An objective designed to be immersed into the culture dish from above (used for microinjection).

Water Immersion Objective

An objective lens designed for use with water to force a continuum between the lens and the coverslip.  Water immersion objectives may result in better resolution when imaging water based biological samples.  Some immersion objectives have an adjustable collar for use with water or glycerol as the immersion media.

Wavelength of Light (l)

The distance in nanometers between nodes in the wavelength of light.  Shorter wavelength light has higher energy.  The color of the light is determined by the wavelength.

WB      

Wide Band filters combine rectangular bandshapes with broad regions of transmission.

Weighted Average

The mechanism of the spatial convolution process.  Pixel brightnesses in a group of input pixels (kernel) are multiplied by corresponding weights (convolution coefficients), and the results are summed.

Well Transformation

A gray scale morphological operation implemented by subtracting a closed ver­sion of an image from the original image; dark object valleys are highlighted.

White Balancing

The calibration of red, green, and blue color component proportions so that mixing all three results in a pure white color without color casts.

White Light

The combination of all three primary colors red, green and blue.  Illuminating all three primary colors together produces White on a computer screen.  However, white on a printed page is produced by the absence of printing ink (displaying white paper).

Wide-field

An epi-fluorescence microscope in which the full field of view is illuminated.

Window

A component of a graphical user interface for viewing input and resulting images and data.

Windowing Function

A function applied to an image prior to applying a Fourier transform (or inverse Fourier transform) to reduce image edge discontinuities as seen by the transform's periodic interpretation of the image.

Windows

The basic on-screen box used in Windows 95/NT/98/Me/2000 to contain and display each and every program on the computer.

Wireframe

The most primitive synthetic image ren­dering method that simply shows the edges of all the surfaces in a three-dimensional model.

Working Distance

The distance between the front lens of the objective and the coverslip.  A long working distance objective is very useful for microinjection, but usually has a lower NA value (lower resolution) and is more expensive compared to a normal short working distance objective.

X-Z Scanning

The ability to collect an image in the X-Z plane by scanning a single line at a series of focal positions.

Y/C Component Color

A component color standard video format conveyed as a luminance signal (Y) and a chrominance signal (C); identical to the S-Video format.

Z-axis  

The vertical axis in a microscope.  Z sections refer to a series of images collected by stepping the fine focus with a focus motor drive.

Zip Disk

A reasonably fast (1/2 the speed of a hard drive) and relatively cheap disk with good capacity (100 or 250 Mbyte).  The drive can be readily moved to different computers by attachment though the printer parallel port or USB port.

Zoom on Collected Image

A portion of a saved image can be zoomed, but this increases the size only with no increase in resolution.  Too much zoom results in a pixilated image.

Zoom While Scanning

Increased magnification can be obtained by zooming the scanned image.  When in zoom mode the object can be moved by using the arrow keys as panning keys.

Z-resolution     

The resolution in the "z" direction (at right angles to the scan direction).  The z-resolution on a microscope is less than the x-y resolution, and is about 0.5 to 0.8 mm when using a high resolution 1.4NA 100x Objective (in contrast the x-y resolution will be approximately 0.2 mm).

 

 

 


See Also

Table of Contents
Function Reference
Menu Reference
Toolbar Reference