imagecolorat
Get the index of the color of a pixel
Description
int imagecolorat
( resource $image
, int $x
, int $y
)
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
-
x-coordinate of the point.
-
y
-
y-coordinate of the point.
Return Values
Returns the index of the color.
Examples
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)
}
See Also
- imagecolorset
- imagecolorsforindex
- imagesetpixel