(PHP 4 >= 4.0.6, PHP 5)imagecolorresolvealpha -- Get the index of the specified color + alpha or its closest possible alternative
This function is guaranteed to return a color index for a requested color, either the exact color or the closest possible alternative.
An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().
Value of red component
Value of green component
Value of blue component
A value between 0 and 127. 0 indicates completely opaque while 127 indicates completely transparent.