(PHP 4, PHP 5)

imagecolorclosestGet the index of the closest color to the specified color


int imagecolorclosest ( resource $image , int $red , int $green , int $blue )

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.

Se l'immagine è stata creata da un file, solo i colori usati nell'immagine sono risolti. I colori presenti solo nella palette non sono risolti.

Elenco dei parametri


Una risorsa immagine, restituita da una delle funzioni di creazione immagine, come imagecreatetruecolor().


Valore della componente rossa.


Valore della componente verde.


Valore della componente blu.

The colors parameters are integers between 0 and 255 or hexadecimals between 0x00 and 0xFF.

Valori restituiti

Returns the index of the closest color, in the palette of the image, to the specified one


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

// Start with an image and convert it to a palette-based image
$im imagecreatefrompng('figures/imagecolorclosest.png');

// Search colors (RGB)
$colors = array(

// 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']})";

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


Il precedente esempio visualizzerà qualcosa simile a:

#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).

Vedere anche:

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User Contributed Notes 3 notes

info at codeworx dot ch
5 years ago
Here is a function that compares two HEX colors for similarity. This can be useful if you want to detect colors that are not different enough to see for the naked eye. It returns a bool: TRUE if the colors are similar to each other (within tolerance) or FALSE if they are different enough.
I tested a few colors and came up with a tolerance of 35 (rgb value - should be between 0 and 255) but you can change that tolerance by passing a third parameter to the function.

function compareColors ($col1, $col2, $tolerance=35) {
$col1Rgb = array(
"r" => hexdec(substr($col1, 0, 2)),
"g" => hexdec(substr($col1, 2, 2)),
"b" => hexdec(substr($col1, 4, 2))
$col2Rgb = array(
"r" => hexdec(substr($col2, 0, 2)),
"g" => hexdec(substr($col2, 2, 2)),
"b" => hexdec(substr($col2, 4, 2))
    return (
$col1Rgb['r'] >= $col2Rgb['r'] - $tolerance && $col1Rgb['r'] <= $col2Rgb['r'] + $tolerance) && ($col1Rgb['g'] >= $col2Rgb['g'] - $tolerance && $col1Rgb['g'] <= $col2Rgb['g'] + $tolerance) && ($col1Rgb['b'] >= $col2Rgb['b'] - $tolerance && $col1Rgb['b'] <= $col2Rgb['b'] + $tolerance);
MagicalTux at FF dot st
11 years ago
A way to get each time an answer :

function imagegetcolor($im, $r, $g, $b) {
$c=imagecolorexact($im, $r, $g, $b);
        if (
$c!=-1) return $c;
$c=imagecolorallocate($im, $r, $g, $b);
        if (
$c!=-1) return $c;
imagecolorclosest($im, $r, $g, $b);

If the *exact* color is found in the image, it will be returned. If we don't have the exact color, we try to allocate it. If we can't allocate it, we return the closest color in the image.
Vikrant Korde <vakorde at hotmail dot com>
13 years ago
This functuion is useful when you are dealing with previously present images like .png, .jpg, etc. You can use this function for writing a text on the image.

For me the function imagecolorallocate() was returning the -1 value. after lot of RnD and site search i found a function use of imagecolorclosest(). This solved my problem of writing the text on the image with customised color.

Actually previously it was writing on the image but the color was not distinct. It was using the same color as of that background image.

The following code segment was fine with me.

header ("Content-type: image/jpeg");
$im = imagecreatefromjpeg("BlankButton.jpg");
$white = imageColorClosest($im, 255,255,255);
// this is for TTF fonts
imagettftext ($im, 20, 0, 16, 30, $white, "/usr/X11R6/lib/X11/fonts/TTF/luximb.ttf", "Vikrant");

//this is for notmal font
imagestring($im, 4, 0,0,"Korde", $white);
imagedestroy ($im);
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