An approach to compare images based on color coherence vectors are presented by Pass, Zabih, & Miller
(1997). They define color coherence as the degree to which image pixels of that color are members of a
large region with homogeneous color. These regions are referred as coherent regions. Coherent pixels are
belongs to some sizable contiguous region, whereas incoherent pixels are not. In order to compute the
CCVs, the method blurs and discretizes the image‘s color-space to eliminate small variations between
neighboring pixels. Then, it finds the connected components in the image in order to classify the pixels of
a given color bucket is either coherent or incoherent. After classifying the image pixels, CCV computes
two color histograms: one for coherent pixels and another for incoherent pixels. The two histograms are
stored as a single histogram.