Double compression

  • Resolved Squazz

    (@squazz)


    4 years, 9 months ago

    As of WordPress 4.5, WordPress uses a default compression setting of 82. This means that when I run through old images, I will by default do a 85% webp compression on top of the 82% compression from WordPress. Resulting in visibly downgraded images.

    What should we do here? Should we disable the default compression from WordPress? Or should we set the webp compression up to 100% so that we won’t lose any more quality?

    Should the plugin tage the original image and generate entirely new resized and compressed images?

Viewing 4 replies - 1 through 4 (of 4 total)
  • Plugin Author kubiq

    (@kubiq)

    I’ve tested it with many various images and with WEBP compression on level above 80% I wasn’t possible to find any difference on images…

    Of course it depend on many criterions – if you use GD or Imagick, if original image was really compressed only once or it was compressed multiple times with Photoshop, extension converts, then WP, etc…

    I think the best way is when you just try to upload few images and then open original images in tab side-by-side and you will see if you need to solve something, but I don’t think so… If you will find image, that is really problematic, then you can send it to me, I’m really curious about it then

    Thread Starter Squazz

    (@squazz)

    I’ve just sent you a mail with 4 images ??

    Plugin Author kubiq

    (@kubiq)

    Wow, final WEBPs are really bad…

    I tried to upload it with GD and also Imagick but results were same…

    Also when I convert your image to JPG with 100% conversion and then upload it to WordPress (without converting to WEBP, without my plugin), the result is almost same, so it means it’s because of GD and Imagick server library, that use probably very similar algorithm for these conversions and it doesn’t matter if you change format or only quality…

    only working format is PNG but it’s too big for such a small image :/

    Next thing I tried is to set 100% quality for Images to Webp and result is pretty good and size is still much smaller than original so maybe this is the way how to do it? But for other images you probably don’t need 100% quality, so maybe switch quality only for a while, only for these images?
    I know it’s not very practical, but I don’t have any other idea right now.

    But there is nothing I can do with this, as it is based on server PHP libraries… you have really specific graphic… not even in Photoshop where I always use 60-70% quality without noticeable changes, now I had to use 90% quality for JPG to export it nicely

    Plugin Author kubiq

    (@kubiq)

    CLOSING THREAD: Some special gradients and specific colors can really look ugly after conversion, but exactly same thing will happen when you convert some PNG to JPG or convert JPG to lower quality JPG – that’s problem with GD and Imagick library algorithm and there is nothing I can do with this

Viewing 4 replies - 1 through 4 (of 4 total)
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