ImageColorAllocate() returns a color identifier representing the color composed of the given RGB components. The im argument is the return from the imagecreate() function. Red, green and blue are the values of the red, green and blue component of the requested color respectively. These parameters are integers between 0 and 255. ImageColorAllocate() must be called to create each color that is to be used in the image represented by im.
Returns -1 if the allocation failed.