(PHP 4, PHP 5, PHP 7, PHP 8)
imagecolorat — Get the index of the color of a pixel
Returns the index of the color of the pixel at the specified location in the image specified by image.
If 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:
imageA GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().
xx-coordinate of the point.
yy-coordinate of the point.
Returns the index of the color or false on failure.
This function may return Boolean false, but may also return a non-Boolean value which evaluates to false. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.
| Version | Description |
|---|---|
| 8.0.0 | image expects a GdImage instance now; previously, a valid gdresource was expected. |
Example #1 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)
Example #2 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) }