Apparatus and methods are described including apparatus (21) for capturing and processing a color video of an interior of a body of a human subject (20). The apparatus (21) includes a medical scope imaging device (22) configured to capture the video, and a medical image processing system (24), which includes a memory (26) and a processor (28). The memory (24) stores a color-reduction table (30), which specifies a plurality of low-occurrence-rate colors. The processor (28) is configured to use the color-reduction table (30) to identify for replacement one or more of the low-occurrence-rate colors in at least one of the frames of the video, and to replace one or more instances of each of the identified low-occurrence-rate colors with a replacement color. Other applications are also described.
