(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 resource 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)
}