Gets the color for a specified index.
A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor.
The color index.
Returns an associative array with red, green, blue and alpha keys that contain the appropriate values for the specified color index.
|image expects a GdImage instance now; previously, a resource was expected.
|imagecolorsforindex now throws a ValueError exception if color is out of range; previously, false was returned instead.