I have several png images that when transformed from png to jpg, the alpha layer is transformed to an horizontally lined pattern.

Therefore I have to keep them as png, wich is in my case unnecessary and a drastic data load issue.

The problem appears in production, wich is an ArcusTech server.

Anyone knows what it could be ?

Thanks !

  • 1
    Are you using GD or Imagick on the server? Also, alpha is transparency which is not supported by jpg. What exactly are you expecting here? Apr 5, 2017 at 11:48
  • Ooooh I've looked into the installed dependencies on my prod, and only GD is installed. As Craft stands: "GD or ImageMagick is required, however ImageMagick is recommended as it adds animated GIF support, and preserves 8-bit and 24-bit PNGs during image transforms.". I asked the ArcusTech team to install it since it could be the issue :-) Usually, alpha layers in png are replaced by plain colors in jpg (and generally plain white) as it does on my local. Thanks already !
    – Antoine
    Apr 5, 2017 at 14:18
  • As Brad pointed out below, let's see how Imagick handles this. Should be much better. Apr 6, 2017 at 6:16

1 Answer 1


You'll need to have Imagick installed on your box if you want to preserve alpha channels in a PNG during transforms.

If Craft sees it is installed, it will use it by default.

  • Thanks for your input ! Imagick is now installed and, surprisingly, the transform alpha layers of my jpgs-transformed-from-pngs are now black and not white as it is on my local
    – Antoine
    Apr 6, 2017 at 10:15
  • Are you running a newish version? imagemagick.org/script/changelog.php and pecl.php.net/package-changelog.php?package=imagick
    – Brad Bell
    Apr 6, 2017 at 18:18
  • Nope :-/ imagick module version 3.4.0RC6 imagick classes Imagick, ImagickDraw, ImagickPixel, ImagickPixelIterator, ImagickKernel Imagick compiled with ImageMagick version ImageMagick 6.8.9-9 Q16 x86_64
    – Antoine
    Apr 10, 2017 at 15:57
  • Maybe try updating those and see if it helps.
    – Brad Bell
    Apr 10, 2017 at 21:56

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