GD and Image Functions
PHP Manual

imagecolorexactalpha

Get the index of the specified color + alpha

Description

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

Returns the index of the specified color+alpha in the palette of the image.

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.

The colors parameters are integers between 0 and 255 or hexadecimals between 0x00 and 0xFF.

Return Values

Returns the index of the specified color+alpha in the palette of the image, or -1 if the color does not exist in the image's palette.

Examples

Example #1 Get colors from the GD logo

<?php

// Setup an image
$im = imagecreatefrompng('./gdlogo.png');

$colors   = Array();
$colors[] = imagecolorexactalpha($im, 255, 0, 0, 0);
$colors[] = imagecolorexactalpha($im, 0, 0, 0, 127);
$colors[] = imagecolorexactalpha($im, 255, 255, 255, 55);
$colors[] = imagecolorexactalpha($im, 100, 255, 52, 20);

print_r($colors);

// Free from memory
imagedestroy($im);
?>

The above example will output something similar to:

Array
(
    [0] => 16711680
    [1] => 2130706432
    [2] => 939524095
    [3] => 342163252
)

Notes

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

See Also

  • imagecolorclosestalpha