imagecolorexactalpha
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.
imagecolormatch
(PHP 4 >= 4.3.0, PHP 5)
imagecolormatch — Fait correspondre un peu plus les couleurs de la version palette d'une image aux couleurs de sa version truecolor
Description
bool imagecolormatch
( resource $image1
, resource $image2
)
Avertissement
Cette fonction n'est pas documentée et seule la liste des arguments est disponible.
Liste de paramètres
- image1
-
Une ressource d'image truecolor
- image2
-
Une ressource 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, FALSE en cas d'échec.
Notes
Note: Cette fonction n'est disponible que si PHP est compilé avec la version embarquée de la bibliothèque GD.
Note: Cette fonction requiert la bibliothèque GD 2.0.1 ou supérieure (2.0.28 ou supérieure est recommandée).
add a note
User Contributed Notesimagecolormatch
albriNOght at anSPAMre dot net
12-Dec-2005 09:22
12-Dec-2005 09:22
Samantha
08-Feb-2004 07:14
08-Feb-2004 07:14
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.