imagecolorresolvealpha

(PHP 4 >= 4.0.6, PHP 5, PHP 7)

Get the index of the specified color + alpha or its closest possible alternative

int imagecolorresolvealpha ( resource $image, int $red, int $green, int $blue, int $alpha )

This function is guaranteed to return a color index for a requested color, either the exact color or the closest possible alternative.

Parameters:

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.

Returns:

Returns a color index.

Notes:

This function requires GD 2.0.1 or later (2.0.28 or later is recommended).

Examples:

Using imagecoloresolvealpha() to get colors from an image

<?php
// Load an image
$im = imagecreatefromgif('phplogo.gif');

// Get closest colors from the image
$colors = array();
$colors[] = imagecolorresolvealpha($im, 255, 255, 255, 0);
$colors[] = imagecolorresolvealpha($im, 0, 0, 200, 127);

// Output
print_r($colors);

imagedestroy($im);
?>

The above example will output something similar to:

Array
(
    [0] => 89
    [1] => 85
)