imagecolorclosestalpha
PHP function
Edit on GitHub ✎
(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)
Get the index of the closest color to the specified color + alpha
Description
imagecolorclosestalpha(GdImage $image, int $red, int $green, int $blue, int $alpha): int
Returns the index of the color in the palette of the image which is "closest" to the specified RGB value and alpha level.
Parameters
redRed
greenGreen
blueBlue
alphaA value between
0and127.0indicates completely opaque while127indicates completely transparent.
The colors parameters are integers between 0 and 255 or hexadecimals between 0x00 and 0xFF.
Return Values
Returns the index of the closest color in the palette.
Examples
Search for a set of colors in an image
php
<?php
// Start with an image and convert it to a palette-based image
$im = imagecreatefrompng('figures/imagecolorclosest.png');
imagetruecolortopalette($im, false, 255);
// Search colors (RGB)
$colors = array(
array(254, 145, 154, 50),
array(153, 145, 188, 127),
array(153, 90, 145, 0),
array(255, 137, 92, 84)
);
// Loop through each search and find the closest color in the palette.
// Return the search number, the search RGB and the converted RGB match
foreach($colors as $id => $rgb)
{
$result = imagecolorclosestalpha($im, $rgb[0], $rgb[1], $rgb[2], $rgb[3]);
$result = imagecolorsforindex($im, $result);
$result = "({$result['red']}, {$result['green']}, {$result['blue']}, {$result['alpha']})";
echo "#$id: Search ($rgb[0], $rgb[1], $rgb[2], $rgb[3]); Closest match: $result.\n";
}
?>The above example will output something similar to:
output
#0: Search (254, 145, 154, 50); Closest match: (252, 150, 148, 0).
#1: Search (153, 145, 188, 127); Closest match: (148, 150, 196, 0).
#2: Search (153, 90, 145, 0); Closest match: (148, 90, 156, 0).
#3: Search (255, 137, 92, 84); Closest match: (252, 150, 92, 0).