PHP Color Picker: Extract the main colors of a given image file

This class can extract the main colors of a given image file.

It can read an image in the GIF, JPEG or PNG format and extracts the list of colors that are used in the pixels of the image.

The class takes in account a similarity factor to consider very similar colors as if they are the same.

It returns an array with the colors used in the picture sorted by the frequency of the pixels that use each color.