When are Histogram Tools Used?

Histograms are important because they are a compact representation of the pixel data contained in the image, stripped of all positional data, i.e. the functions only return information about the number of pixels in the ROI, and their individual greyscale (or color) values. This means that all of the position-independent greyscale image statistics can be computed directly from the histogram array.

The Histogram Tools are useful in examining images for issues such as detecting the presence/absence of a feature, checking the illumination values or qualifying the uniformity of greyscale values to determine if there are any scratches, dust or debris.