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
(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
imagecolormatch — パレットイメージの色を True カラーイメージに近づける
image1truecolor イメージオブジェクト
image2
パレットイメージオブジェクト。
image1 と同じ大きさの画像を指します。
| バージョン | 説明 |
|---|---|
| 8.0.0 |
image1 と
image2 は、
GdImage
クラスのインスタンスを期待するようになりました。
これより前のバージョンでは、
resource が期待されていました。
|
例1 imagecolormatch() の例
<?php
// true color 画像とパレット画像を用意します
$im1 = imagecreatefrompng('./gdlogo.png');
$im2 = imagecreate(imagesx($im1), imagesy($im1));
// いくつかの色を $im2 に追加します
$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);
// これらの色を true color 画像にマッチさせます
imagecolormatch($im1, $im2);
// メモリから開放します
imagedestroy($im1);
imagedestroy($im2);
?>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/yel4r7tThis 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.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.