PHP imagecolorallocate(): Allocate a Color for an Image

The imagecolorallocate() function in PHP creates a color identifier for a given image resource by combining red, green, and blue components. The RGB values can be supplied as integers ranging from 0 to 255 or as hexadecimal values (0x00‑0xFF).

Parameters: resource $image – the image resource to which the color will be applied; int $red, int $green, int $blue – the intensity of each color channel.

Return value: On success, the function returns an integer identifier representing the allocated color. If the allocation fails, it returns -1.

Example usage:

<?php
$im = imagecreate('example.jpg', 100, 100);
// Set background to red
$background = imagecolorallocate($im, 255, 0, 0);
// Define additional colors
$white = imagecolorallocate($im, 255, 255, 255);
$black = imagecolorallocate($im, 0, 0, 0);
// Using hexadecimal notation
$whiteHex = imagecolorallocate($im, 0xFF, 0xFF, 0xFF);
$blackHex = imagecolorallocate($im, 0x00, 0x00, 0x00);
?>