imagecolorset

(PHP 4, PHP 5, PHP 7, PHP 8)

imagecolorset — Set the color for the specified palette index

Description

imagecolorset(
    GdImage $image,
    int $color,
    int $red,
    int $green,
    int $blue,
    int $alpha = 0
): ?false

This sets the specified index in the palette to the specified color. This is useful for creating flood-fill-like effects in palleted images without the overhead of performing the actual flood-fill.

Parameters

image: A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().
color: An index in the palette.
red: Value of red component.
green: Value of green component.
blue: Value of blue component.
alpha: Value of alpha component.

Return Values

The function returns null on success, or false on failure.

Changelog

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

Examples

Example #1 imagecolorset() example

<?php
// Create a 300x100 image
$im = imagecreate(300, 100);

// Set the background to be red
imagecolorallocate($im, 255, 0, 0);

// Get the color index for the background
$bg = imagecolorat($im, 0, 0);

// Set the background to be blue
imagecolorset($im, $bg, 0, 0, 255);

// Output the image to the browser
header('Content-Type: image/png');

imagepng($im);
?>