Thresholding an image

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Click Color»Color Threshold or click Color Threshold in the Color tab of the Processing Functions palette.
Select the color model (RGB, HSL, HSV, or HSI) you want to use to process the image.
Adjust the blue and red lines on the Red (Hue), Green (Saturation), and Blue (Luminance/Value/Intensity) histograms until all of the particles of interest are highlighted with the color specified in Preview Color.
Click OK to threshold the image and add this step to the script.

Tips

If you have trouble finding a threshold range that selects all of the pixels in the range, draw an ROI around the portion of the image that you want to keep. The histogram displays the intensities of the ROI only. Use the minimum and maximum values for the threshold.
You can display the histogram in either linear or logarithmic form.