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(PHP 4, PHP 5, PHP 7)

imagecolorclosestRetorna o índice da cor mais próxima da cor especificada


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

Retorna o índice da cor na paleta da imagem que seja mais "próxima" do valor RGB especificado.

A "distancia" entre a cor desejada e cada cor da paleta é calculada como se os valores RGB representassem pontos em um espaço tridimencional.

Se você criou a imagem a partir de um arquivo, apenas as cores usadas na imagem são resolvidas. Cores presentes apenas na paleta não são resolvidas.

Veja também imagecolorexact().

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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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