imagecreatefromwebp() -> imagejpeg() results in blue channel missing

Question

I am losing color information, seemingly the blue channel, from an image after using GD to read from the WebP version and output a JPEG. Why does this happen and how can I fix it?

Original Image

Code

$pic = imagecreatefromwebp('https://lh4.ggpht.com/uaLB-tbci94IubJJhDZ4n6vJwGF4i9MpFLXl28LBHjVzLIy-K6fhoSILbM4yJcKqq9I=h900-rw');
imagejpeg($pic, './example.jpg', 80);
imagedestroy($pic);

Resulting Image

pic here http://savepic.ru/7812459.png

I suspect that this is a bug in GD for reading the WebP image. Or, the original image has a problem preventing a proper conversion. The original WebP version has no colorspace, but that shouldn't be a problem in most cases. http://regex.info/exif.cgi?imgurl=https%3A%2F%2Flh4.ggpht.com%2FuaLB-tbci94IubJJhDZ4n6vJwGF4i9MpFLXl28LBHjVzLIy-K6fhoSILbM4yJcKqq9I%3Dh900-rw — Brad, Sep 20 '15 at 20:32
Just FYI, ImageMagick has no problem reading it and making a JPEG of it... `convert https://lh4.ggpht.com/uaLB-tbci94IubJJhDZ4n6vJwGF4i9MpFLXl28LBHjVzLIy-K6fhoSILbM4yJcKqq9I=h900-rw image.jpg` — Mark Setchell, Sep 20 '15 at 21:49

timclutton · Answer 1 · 2015-09-21T16:05:53.417

3

This looks like PHP bug #70102, "imagecreatefromwebm() shifts colors".

It is fixed in PHP >= 5.6.12 (release notes).

Your script works correctly for me (there is no yellow tint) in PHP 5.6.13

edited Sep 21 '15 at 16:05

answered Sep 21 '15 at 15:58

timclutton

12,682
3
33
43

my PHP version => PHP Version 5.6.13-1+deb.sury.org~trusty+3, and don't work – emtecif Sep 21 '15 at 19:26
Same here, my php version is 5.6.17 and I have the yellow hue as well :/ – Marc Went Mar 08 '16 at 17:13
I have PHP 5.6.4 on Apache on a windows machine, and I'm getting a similar error with the transparency. – Ben Grant Nov 09 '16 at 08:40
php7.0 and same situation exists here. By the way on windows wamp server setup everything is fine. there is no problem. – İsmail Ceylan May 04 '17 at 21:40

Sven Liivak · Answer 2 · 2018-09-26T07:38:10.247

Seems like there's couple of bits too many...

function fixBlue($im)
{
    $f_im = imagecreatetruecolor(imagesx($im),imagesy($im));
    $c = imagecolorallocate($f_im, 255, 255, 255);
    imagefill($f_im, 0, 0, $c);

    for($y=0;$y<imagesy($im);$y++)
    {
        for($x=0;$x<imagesx($im);$x++)
        {
            $rgb_old = imagecolorat($im, $x, $y);
            $r = ($rgb >> 24) & 0xFF;
            $g = ($rgb >> 16) & 0xFF;
            $b = ($rgb >> 8) & 0xFF;
            $pixelcolor = imagecolorallocate($f_im, $r, $g, $b);
            imagesetpixel($f_im, $x, $y, $pixelcolor);
        }
    }
    return $f_im;
}

and then just:

$img = imagecreatefromwebp('https://lh4.ggpht.com/uaLB-tbci94IubJJhDZ4n6vJwGF4i9MpFLXl28LBHjVzLIy-K6fhoSILbM4yJcKqq9I=h900-rw');
$img_f = fixBlue($img, 60);

ob_end_clean();
header('Content-type: image/jpeg');
imagejpeg($img_f, null, 80);

imagedestroy($img);
imagedestroy($img_f);

I can test with PHP 5 only, dont know about PHP 7. – Sven Liivak Sep 12 '18 at 20:50 — Sven Liivak, Sep 12 '18 at 20:50

imagecreatefromwebp() -> imagejpeg() results in blue channel missing

Original Image

Code

Resulting Image

2 Answers2