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Northern
Eclipse Help Reference |
Measuring Monochrome Objects Tutorial |
This tutorial demonstrates opening and then measuring a sample monochrome image.
Click on the Open button from the toolbar menu (see Toolbar Configuration) found along the top of the Northern Eclipse main menu, and then highlight the sample image Beads.bmp and click open.
Now the image must be thresheld to count or measure multiple objects.
From the toolbar click on the threshold button. Since all of the objects are lighter than the dark background, set the higher Threshold Range to (To) 255 and the lower range to 74 (From), using the slide bars on the Grayscale Thresholding dialog box.
What this means is that all objects with a gray value of 74 and greater will be measured. (Which in this case includes all of the beads.)
Click on Close and at this point all of the beads will be highlighted with a RED overlay, tagging the objects to be measured.
If only a subset of objects require measuring, click on the Square Selection Tool from the Tool Window ( any selection tool may be used at this point, i.e. curve, poly, circle ) and then move the mouse cursor to the upper left quadrant of the image. Hold down the left mouse button pulling a box toward the lower right quadrant, encompassing many of the beads. Now a selection mask will be drawn on the image outlining a region of objects.
Next, click on the Measure button from the toolbar menu.
At this point all of the selected objects in the field outlined by the box will be measured and a Data Results menu will pop up.
In the Data Results menu, click on LOG to DDE to send this data to Excel or any other program that has been setup in the DDE path (see DDE Options) that supports Dynamic Data Exchange.
You can also click on Log to File to send the data to a local or network file in a comma-delimited format. All spreadsheet and database programs support this import file format.
There is another button labeled Graph that brings up a graph of the currently selected object parameter. It interacts with the results window so that if you sort the data in the results window, the graph window is updated accordingly. Also, if you change the selection in the graph window, the results window is updated. The current Selection can be changed by using the Select and Remove buttons and by directly selecting a range of the graph using the mouse.
If there are only a small number of selected objects, the data is graphed as a bar graph. Once the number of objects gets too large, the graph automatically switches to a line graph. The Graph window is resizable so that you can make the graph any size you like. The Copy Button will copy the current graph to the clipboard at the current graph window size.
The drop down box changes what data is graphed but does
not cause resorting to occur. This
allows you to sort the data by one parameter but graph another parameter. If you select a non-numeric parameter to
graph, the area parameter will be graphed.
Options:
In the example above only the beads within the selected region were measured because in Data Options, Excluded from Selection was the option set. If Cut by Selection is used, then the objects will be cut by the selection mask and only cut portions within the selected region will be measured (this option is useful for densitometry). The Included in Selection option will force all of the objects within the selection to be measured, including those objects touching the selection mask. Excluded/Included by Centroid will force all of the objects within the selection to be measured, including those objects touching the selection mask, if the center of gravity of the given object is within the selection mask (This is statistically the best method for multiple measurements of many fields).
Hints:
There
are a number of ways to discard unwanted data. As the example
demonstrates, threshold is one of the first methods to try, but there are many
other things one can do to get the desired results and measurements required.
For example: discarding objects under a certain pixel size (see data options
menu), binning objects by morphometric characteristics (see binning), object
separation using binary operations. (see binary operations and Object
Separation Tutorial), and sorting and excluding from the Data Results window
(see Data Results). It is also
possible to remove unwanted object measurements by closing the Data Results
window and then right clicking on objects (after measurements have made).
After selecting the object to be discarded by right clicking on it, left click and it will be pulled out of the Data Results. At this point do not re-measure, but instead, under the Measure column from the main menu bar, click on Show Data Results Window. The object or objects removed by right and left clicking will no longer be part of the data set, and can then be logged to Excel.
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