GD and Image Functions
PHP Manual

imagecolorexactalpha

Get the index of the specified color + alpha

Description

int imagecolorexactalpha(
    GdImage $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

A GdImage object, 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.

Changelog

Version Description
8.0.0 image expects a GdImage instance now; previously, a valid gd resource was expected.

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
)

See Also

  • imagecolorclosestalpha