在PHP中更改动画gif中的颜色

Question

有没有可行的示例，如何使用GD库或ImageMagick读取动画gif，更改其任何帧中任何像素的颜色并将其再次另存为动画gif？

我已经搜寻了2天，却在任何地方都找不到答案。

编辑：我有几乎完美的解决方案。 但是某些透明（经过动画处理）的gif不能正确保留其透明性（仅部分透明性已损坏）。

资源：

• 错误图片之一： http : //commons.wikimedia.org/wiki/File : Animation30.gif
• GifFrameExtractor类： https : //github.com/Sybio/GifFrameExtractor

• GIFEncoder类： http ://www.phpclasses.org/package/3163-PHP-Generate-GIF-animations-from-a-set-of-GIF-images.html

   require_once('GIFEncoder.class.php'); require_once('GifFrameExtractor-master/src/GifFrameExtractor/GifFrameExtractor.php'); $gifFilePath = "input.gif"; // check this is an animated GIF if (!\\GifFrameExtractor\\GifFrameExtractor::isAnimatedGif($gifFilePath)) { \\die('not an namiated image'); } $gfe = new \\GifFrameExtractor\\GifFrameExtractor(); $gfe->extract($gifFilePath); // frames as a GD source $frameImages = $gfe->getFrameImages(); $frameDurations = $gfe->getFrameDurations(); // color used as a transparent color, if any $tColor = array('red' => -1,'green'=>-1,'blue'=>-1); foreach($frameImages as $i => $gdSource) { // do something with gdSource colorize($gdSource); if($i == 0) { //get the color used as transparent // should be for any frame the same $tColor = getTransparentColor($gdSource); } //GIFEncoder works only with binary data or files //It cant work with gd source //Therfore i output the gd source to stdout, catch it //and use it as binary data. //It could be memory consuming, so you might write the //frames as a file and then use them instead of binary data. \\ob_start(); // catch output \\imagegif($gdSource); // write binary data to output $frameImages[$i] = \\ob_get_contents(); //replace GD source by the binary data \\ob_end_clean(); } // create animated gif $gif = new \\GIFEncoder( $frameImages, //binary data (or path to images on file system) $frameDurations, 0, // infinite loop 2, // dont know what is this for (number 0-3 or -1 to ignore) $tColor['red'], $tColor['green'], $tColor['blue'], 'bin' // or 'url' if $frameImages is array of paths to images on file system ); // write image to file system \\FWrite ( \\FOpen ( "output.gif", "wb" ), $gif->GetAnimation ( ) ); // send image to browser //Header ( 'Content-type:image/gif' ); //echo $gif->GetAnimation ( ); 

//有用的功能

    /**
     * Make grayscale color
     * @param $color array('red'=>,'green'=>,'blue'=>);
     * @return array('red'=>,'green'=>,'blue'=>);
     */
    function transformColor($color) {
        $gst = $color['red']*0.15+$color['green']*0.5+$color['blue']*0.35;
        $color['red'] = $color['green'] = $color['blue'] = $gst;
         return $color;
    }  

//有用的功能

    /**
     * Get the transparent color from GD resource.
     * If no tranpsarent color, all returned RGB values are -1
     * @param $rs GD resource
     * @return array('red'=>,'green'=>,'blue'=>)
     */
    function getTransparentColor($rs) {
        $transparentIndex = \ImageColorTransparent($rs);
        $transparentColor = NULL;

        if ($transparentIndex >= 0 && $transparentIndex < \ImageColorsTotal($rs)) {
            $transparentColor = @\ImageColorsForIndex($rs, $transparentIndex);
        }
        return $transparentColor ? $transparentColor : array('red' => -1,'green'=>-1,'blue'=>-1);
    }

//用透明方式转换GD资源//可能存在问题，因为如果我单独保存帧，它们就会遇到上述透明性问题

    function colorize($rs) {
        assert('gd' === \get_resource_type($rs));
            // you might want to create copy of the source here 
            // (instead of resource alias)
            $bild = $rs;

            //width
            $x = \imagesx($bild);
            // height
            $y = \imagesy($bild);

            $transparentIndex = \ImageColorTransparent($rs);
            $transparentColor = NULL;

            if ($transparentIndex >= 0 && $transparentIndex < \ImageColorsTotal($bild)) {

                $transparentColor = @\ImageColorsForIndex($rs, $transparentIndex);
            }

            \ImageSaveAlpha($bild, TRUE);
            \ImageAlphaBlending($bild, FALSE);

            $transparentNewIndex = NULL;
            $transparentNewColor = NULL;

            if (!empty($transparentColor)) {
                $transparentIndexNew = \ImageColorAllocate($bild, 255, 0, 255);
                \ImageColorTransparent($bild, $transparentIndexNew);
                $transparentColorNew = @ImageColorsForIndex($bild, transparentIndexNew);
            }
             // transform pixels
            for ($i = 0; $i < $y; $i++) {
                for ($j = 0; $j < $x; $j++) {
                    $index = \imagecolorat($rs, $j, $i);
                    $color = \imagecolorsforindex($rs, $index);
                    if ($index === $transparentIndex) {
                        $col = $transparentIndexNew;
                    } else {
                        $rgb = transformColor($color);
                        //TODO: we have a problem here, if $rgb ~= $transparentColorNew,
                        //      then this pixel will be transparent and not the desired  color
                        $col = \imagecolorresolvealpha($bild, $rgb['red'], $rgb['green'], $rgb['blue'], intval($color['alpha']));
                        if($col == $transparentIndexNew) {
                            //TODO: fix the color not to be transparent
                            // it do not die with the example gif 
                            //die('This might be a problem, but not the problem describlet above this example');
                        }
                    }
                    \imagesetpixel($bild, $j, $i, $col);
                }
            }

            return $bild;
        }

Answer 1

我相信动画GIF具有多个帧，因此，该算法将把gif读取为多个帧，更改每个帧中的像素颜色，然后再次保存。 您可以在GD中加载动画gif吗？

也许这个库可以帮助您写回GIF图像： http : //www.phpclasses.org/package/3163-PHP-Generate-GIF-animations-from-a-set-of-GIF-images.html

Answer 2

$file = "yourImage.gif";
$im = imagecreatefromgif ($file);

$index = imagecolorclosest ( $im,  255,255,255 ); // get your color (rgb)
imagecolorset($im,$index,92,92,92); // set new color (rgb)

$file= "yourResult.gif";
imagegif($im, $file); // save image as gif
imagedestroy($im);

我不确定这是否适用于动画gif。