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