imagecolorallocate() returns a color identifier representing the color composed of the given RGB components. 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 or hexadecimals between 0x00 and 0xFF. imagecolorallocate() must be called to create each color that is to be used in the image represented by image.
Note: The first call to imagecolorallocate() fills the background color in palette-based images - images created using imagecreate().
Returns -1 if the allocation failed.
See also imagecolorallocatealpha() and imagecolordeallocate().