Automatic processing of digital images of falling raindrops is complicated by a less than ideal grayscale image histogram. These histograms do not display a bimodal shape and lack an easily defined minimum, making it difficult to choose a threshold for creating a binary image. To help identify peaks in these histograms, and simplify threshold selection, a histogram modification technique originally developed by Peleg is used. This method was modified slightly and then applied to raindrop image processing. Its performance is quantified.