imagecolorat

(PHP 4, PHP 5, PHP 7)

Get the index of the color of a pixel

int imagecolorat ( resource $image, int $x, int $y )

Returns the index of the color of the pixel at the specified location in the image specified by image.

If PHP is compiled against GD library 2.0 or higher and the image is a truecolor image, this function returns the RGB value of that pixel as integer. Use bitshifting and masking to access the distinct red, green and blue component values:

Parameters:

image

An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().

x-coordinate of the point.

y-coordinate of the point.

Returns:

Returns the index of the color.

Examples:

Access distinct RGB values

<?php
$im = imagecreatefrompng("php.png");
$rgb = imagecolorat($im, 10, 15);
$r = ($rgb >> 16) & 0xFF;
$g = ($rgb >> 8) & 0xFF;
$b = $rgb & 0xFF;
 
var_dump($r, $g, $b);
?>

The above example will output something similar to:

int(119)
int(123)
int(180)

Human-readable RGB values using imagecolorsforindex()

<?php
$im = imagecreatefrompng("php.png");
$rgb = imagecolorat($im, 10, 15);
 
$colors = imagecolorsforindex($im, $rgb);
 
var_dump($colors);
?>

The above example will output something similar to:

array(4) {
  ["red"]=>
  int(119)
  ["green"]=>
  int(123)
  ["blue"]=>
  int(180)
  ["alpha"]=>
  int(127)
}