imagecolormatch

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

imagecolormatch — Fait correspondre un peu plus les couleurs de la version palette d'une image aux couleurs de sa version truecolor

Description

imagecolormatch(GdImage $image1, GdImage $image2): bool

Fait correspondre un peu plus les couleurs de la version palette d'une image aux couleurs de sa version truecolor.

Liste de paramètres

image1: Un objet d'image truecolor.
image2: Un objet de palette d'image pointant sur une image qui a la même taille que image1.

Valeurs de retour

Cette fonction retourne true en cas de succès ou false si une erreur survient.

Historique

Version	Description
8.0.0	`image1` et `image2` attend désormais des instances de GdImage ; auparavant, resources étaient attendues

Exemples

Exemple #1 Exemple avec imagecolormatch()

<?php
// Définit l'image true color et la palette
$im1 = imagecreatefrompng('./gdlogo.png');
$im2 = imagecreate(imagesx($im1), imagesy($im1));

// Ajout de quelques couleurs à $im2
$colors   = Array();
$colors[] = imagecolorallocate($im2, 255, 36, 74);
$colors[] = imagecolorallocate($im2, 40, 0, 240);
$colors[] = imagecolorallocate($im2, 82, 100, 255);
$colors[] = imagecolorallocate($im2, 84, 63, 44);

// Fait correspondre ces couleurs avec l'image true color
imagecolormatch($im1, $im2);

// Libération de la mémoire
imagedestroy($im1);
imagedestroy($im2);
?>

Voir aussi

imagecreatetruecolor() - Crée une nouvelle image en couleurs vraies

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User Contributed Notes 3 notes

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gk at karko dot net ¶

14 years ago


Those that have Ubuntu servers note, that this function is added in PHP's GD library fork and is not available by default in Ubuntu php5-gd package.

Here's how-to install the PHP GD version: http://preview.tinyurl.com/yel4r7t

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albriNOght at anSPAMre dot net ¶

18 years ago


This function appears to work by changing the values of the colors of the paletted image -- no good if you're trying to force the resultant image to stick with certain pre-defined color values.

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-1

Samantha ¶

20 years ago


This function is a godsend! It works exactly as documented.

I'm working on an application where I need to take a transparent GIF, matte the GIF on a user defined background color, and finally scale the GIF based on a user defined %.

The only way I could get this to work so that the final image was high quality, ie: no jagged edges, and a smooth scale, was to convert the GIF to a JPG, and then copy the JPG into a new GIF image like this:

// open transparent gif
$GIFimg = imagecreatefromgif($file_path);

// create jpg image
$JPGimg = imagecreatetruecolor($width, $height);

// copy GIF to JPG
imagecopy($JPGimg, $GIFimg, 0, 0, 0, 0, $width, $height); 

// create a true color image
$JPGscaled = imagecreatetruecolor($n_width, $n_height);

// scale the new JPG using the truecolor image
imagecopyresampled($JPGscaled, $JPGimg, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

// create final GIF image
$GIFfinal = imagecreate($n_width, $n_height);

// copy the scaled JPG back to a GIF
imagecopymerge($GIFfinal, $JPGscaled, 0, 0, 0, 0, $n_width, $n_height, 100);

This worked great except the final step, copying the JPG to a GIF. If the JPG had too many colors, the function would index the colors to make it a palette image. So what would end up happening is the final image contained INCORRECT colors.

Adding this one line at the bottom of the code fixed everything.

imagecolormatch($JPGscaled, $GIFfinal);

I hope this helps anyone who is converting images back and forth and dealing with palette issues and color correction. Also, be aware that the above code is a sample and will not work by copying and pasting.

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