PHP Manual
GD and Image Functions
Get the index of the closest color to the specified color

imagecolorclosest

(PHP 4, PHP 5, PHP 7, PHP 8)

imagecolorclosest — Get the index of the closest color to the specified color

Description

imagecolorclosest(
    GdImage $image,
    int $red,
    int $green,
    int $blue
): int

Returns the index of the color in the palette of the image which is "closest" to the specified RGB value.

The "distance" between the desired color and each color in the palette is calculated as if the RGB values represented points in three-dimensional space.

If you created the image from a file, only colors used in the image are resolved. Colors present only in the palette are not resolved.

Parameters

image: A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().
red: Value of red component.
green: Value of green component.
blue: Value of blue component.

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 of the image, to the specified one

Changelog

Version	Description
8.0.0	`image` expects a GdImage instance now; previously, a resource was expected.

Examples

Example #1 Search for a set of colors in an image


<?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),
    array(153, 145, 188),
    array(153, 90, 145),
    array(255, 137, 92)
);

// 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)
{
    $result = imagecolorclosest($im, $rgb[0], $rgb[1], $rgb[2]);
    $result = imagecolorsforindex($im, $result);
    $result = "({$result['red']}, {$result['green']}, {$result['blue']})";

    echo "#$id: Search ($rgb[0], $rgb[1], $rgb[2]); Closest match: $result.\n";
}

imagedestroy($im);
?>

The above example will output something similar to:

#0: Search (254, 145, 154); Closest match: (252, 150, 148).
#1: Search (153, 145, 188); Closest match: (148, 150, 196).
#2: Search (153, 90, 145); Closest match: (148, 90, 156).
#3: Search (255, 137, 92); Closest match: (252, 150, 92).