PHP imagecolorclosestalpha() Get the index of the color closest to the specified color and opacity

PHP Image Processing

imagecolorclosestalpha — Get the index of the color closest to the specified color and opacity.

Syntax

int imagecolorclosestalpha ( resource $image , int $red , int $green , int $blue , int $alpha )

Returns the color in the image palette that is 'closest' to the specified RGB value and alpha depth.

parameter

• imageThe image resource returned by the image creation function (such as imagecreatetruecolor()).

• redred

• The value of the red component.green

• The value of the green component.blue

• The value of the blue component.alpha 127 The value between 0 and127 represents complete transparency.

The color parameter is a value between 0 and 255 is an integer between 0 and 255, or a hexadecimal number between 0x00 and 0xFF.

Return value

Return the index of the closest color in the palette.

Example

Search for a set of colors in an image.

<?php
//　Start from an image and convert it to a palette-based image
$im = imagecreatefrompng('figures/imagecolorclosest.png');
imagetruecolortopalette($im, false,　255);
//　Search color (RGB)
$colors = array(
　　　　array(254,　145,　154,　50),
　　　　array(153,　145,　188,　127),
　　　　array(153,　90,　145, 0),
　　　　array(255,　137,　92,　84)
);
//　Loop through to find the closest color in the palette
//　Return the number of searches, the searched RGB and the closest matching RGB
foreach($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: $result.\n";
}
imagedestroy($im);
?>

The output of the above examples is similar to:

#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).

Related articles

• imagecolorexactalpha() Get the index value of the specified color with transparency.

• imagecolorclosest() Get the index value of the color closest to the specified color.

• imagecolorclosesthwb() Get the index of the black and white color closest to the given color.

PHP Image Processing