PHP:将png和gif转换为灰度

问题描述

im使用以下脚本将jpgs转换为灰度图像. http://bubble.ro/How_to_convert_an_image_to_grayscale_using_PHP.html

im using the following script to convert jpgs into grayscale-images.http://bubble.ro/How_to_convert_an_image_to_grayscale_using_PHP.html

我想对其进行升级，以将png(具有透明性)和gif(具有透明性)也转换为灰度图像.

i want to upgrade it to also convert pngs (with transparency) and gifs (with transparency) into grayscale images.

目前无法正常工作.我正在查询image-src的文件扩展名.如果是jpg，if，gif或png，我会调用适当的imagecreatefrom-jpg-gif-png

At the moment it's not working. I'm querying the image-src for its file-extension. If jpg, if, gif, or if png i call the appropriate imagecreatefrom-jpg-gif-png

但是，我一直在运行相同的for循环，但是gif只能得到灰色矩形，每个像素都是灰色. Png几乎可以正常工作，但是png中的透明度变成了黑色.

However i'm always running the same for-loop and gifs unfortunately only get gray rectangles, every pixel is gray. Png's almost work, however transprency in pngs gets transformed to black.

有什么想法吗?

推荐答案

$image = ImageCreateFromString(file_get_contents('/path/to/image.ext'));

ImageFilter($image, IMG_FILTER_GRAYSCALE);

ImageGIF($image); // or ImagePNG($image);

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