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本文檔使用 php中文網手册 發布
(PHP 4 >= 4.3.0, PHP 5, PHP 7)
imagecolormatch — 使一个图像中调色板版本的颜色与真彩色版本更能匹配
$image1
, resource $image2
)使一个图像中调色板版本的颜色与真彩色版本更能匹配。
image1
真彩色图像连接资源。
image2
必须是调色板图像,而且和 image1
的大小必须相同。
成功时返回 TRUE
, 或者在失败时返回 FALSE
。
Example #1 imagecolormatch() 例子
<?php
// Setup the true color and palette images
$im1 = imagecreatefrompng ( './gdlogo.png' );
$im2 = imagecreate ( imagesx ( $im1 ), imagesy ( $im1 ));
// Add some colors to $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 );
// Match these colors with the true color image
imagecolormatch ( $im1 , $im2 );
// Free from memory
imagedestroy ( $im1 );
imagedestroy ( $im2 );
?>
Note: 此函数仅在与 GD 库捆绑编译的 PHP 版本中可用。
Note: 此函数需要 GD 2.0.1 或更高版本(推荐 2.0.28 及更高版本)。
[#1] gk at karko dot net [2010-06-28 09:42:11]
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
[#2] albriNOght at anSPAMre dot net [2005-12-12 09:22:15]
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.
[#3] Samantha [2004-02-08 19:14:41]
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.