imagecolormatch

说明

bool imagecolormatch ( resource image1, resource image2 )

警告

本函数暂无文档，仅有参数列表。

image1 必须是真彩色图像，image2 必须是调色板图像，而且 image1 和 image2 的大小必须相同。

如果成功则返回 TRUE，失败则返回 FALSE。

注: 本函数仅在 PHP 与其捆绑的 GD 库一起编译时可用。

注: 本函数需要 GD 2.0.1 或更高版本。

参见 imagecreatetruecolor()。

add a note User Contributed Notes

albriNOght at anSPAMre dot net
13-Dec-2005 01:22


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.

Samantha
09-Feb-2004 11:14


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.

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