Detailed explanation of the steps to implement inverse color processing of images in PHP

This time I will bring you a detailed explanation of the steps for inverting images in PHP. What are the precautions for inverting images in PHP? The following is a practical case, let’s take a look.

Today I have a need to use PHP to invert the color of the image and convert it to gray. I didn’t know if it was possible before, but then I saw the

imagefilter() function, which is more than enough to convert it to gray. It is so powerful. ;

imagefilter($im, IMG_FILTER_GRAYSCALE)

Of course, some people also set gray in css

<style type="text/css">
img {
-webkit-filter: grayscale(1);/* Webkit */
filter:gray;/* IE6-9 */
filter: grayscale(1);/* W3C */
}
</style>

php color change code:

<?php
/**
* 主要用于图片的处理函数
*/
//图片的反色功能
function color($url) {
  //获取图片的信息
  　　list($width, $height, $type, $attr)= getimagesize($url);
  　　$imagetype = strtolower(image_type_to_extension($type,false));
  　　$fun = 'imagecreatefrom'.($imagetype == 'jpg'?'jpeg':$imagetype);
  　　$img = $fun($url);
  　　for ($y=0; $y < $height; $y++) {
    　　for ($x=0; $x <$width; $x++) {
    　　　　//获取颜色的所以值
    　　　　$index = imagecolorat($img, $x, $y);
    　　　　//获取颜色的数组
    　　　　$color = imagecolorsforindex($img, $index);
    　　　　//颜色值的反转
    　　　　$red = 256 - $color['red'];
    　　　　$green = 256 - $color['green'];
    　　　　$blue = 256 - $color['blue'];
    　　　　$hex = imagecolorallocate($img, $red, $green, $blue);
    　　　　//给每一个像素分配颜色值
    　　　　imagesetpixel($img, $x, $y, $hex);
  　　　　}
  　　}
  　　//输出图片
  　　switch ($imagetype) {
    　　case 'gif':
    　　imagegif($img);
    　　break;
  　　　　case 'jpeg':
    　　imagejpeg($img);
    　　break;
  　　　　case 'png':
    　　imagepng($img);
    　　break;
  　　　　default:
    　　break;
  　　}
}

Test code:

$imgurl='1.jpg';
echo color($imgurl);

Original picture (take this childhood-ruining spoof picture commonly used by the editor as an example):

After running (this is mainly for testing, As for whether the picture subverts the three views or the five senses, the editor will not ask too much~):

I believe you have mastered the method after reading the case in this article. For more exciting things, please pay attention to php Other related articles on the Chinese website!

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