(PHP 4 >= 4.0.6)
int imagecolorclosestalpha (resource im, int red, int green, int blue, int alpha)
int imagecolorclosestalpha
Returns the index of the color in the palette of the image which is "closest" to the specified RGB value and alpha level.
See also imagecolorexactalpha().
注意 この関数はPHP 4.0.6で追加され、GD 2.0.1を必要とします。