White (#FFFFFF) becomes yellowish (#FCFEFC) while resizing GIF

[raidoa]

Hi,

Just discovered a challenge where uploaded GIF files will be turned bit yellow after resizing.
JPG and PNG are fine.

Will it go under bug or is something missing from the code?

Using version 2.4 with rather plain code:

use Intervention\Image\ImageManagerStatic as Image;

$inputFile = "input.gif";
$img = Image::make($inputFile)->widen(1024, function ($constraint) {
    $constraint->upsize();
  }
);
$img->save("output.gif");

output.gif:

input.gif:

[ghost]

I realize this issue was created over 2 years ago now, but I am seeing the same issue with GIFs in version 2.5. This is the single mention of the issue that I've been able to find anywhere on the interwebs. I'd be grateful if anyone had any suggestions on a fix or workaround.

[Sublan]

use Imagick;
$im = new Imagick($image);
$im->resizeImage(500,582,(FIlter),1,false);
that filter para causing the issues,if I resize without (filter),param (No change in color in output image).
Resize Using Imagick Solves,But I dnt know how to edit resize method in Intervention.

[olivervogel]

Unfortunately, this happens when GIF formats (with an indexed color palette) are converted with the GD Library to Truecolor and then transformed back to an indexed color format.

This is only indirectly related to this library.:

// example without intervention image
$gd = imagecreatefromgif('ffffff.gif'); // complety white image
imagepalettetotruecolor($gd);
imagegif($gd, 'output.gif'); // white becomes yellowish

With Intervention Image, all formats are always normalized to truecolor format with GD. This ensures that the image quality is maintained during operations.

Unfortunately, I cannot offer a bugfix at the moment and can only recommend switching to Imagick.