Forum:Degraded JPG thumbnails after gallery update

The recent gallery update has brought along another problem with regards to image thumbnails.

Until then, the sharpness and quality of thumbnails are dependent on the quality of full image uploaded; this has led me to upload high quality JPG images that automatically generate crisp thumbnail images capable of illustrating subject matters in greater detail. Having only surfaced late last year, the feature proved to be handy in galleries, where it's necessary to keep image size small.

The update has now led every JPG thumbnail to be generated in degraded quality, affecting every image I've uploaded since the update; strangely, these degraded thumbnails are still saved in the same JPG quality as the original image. Compare (before) with  (after), for example.

PNG and GIF images, being loseless formats, are apparently unaffected.

Disappointing, to say the least. - ZS 18:43, July 15, 2010 (UTC)
 * I don't see any difference in quality between the 2 images you've linked -- Random Time  20:53, July 15, 2010 (UTC)


 * What about these? ( and ) The former is a cached thumbnail from before the update; the latter is a thumbnail generated by force after the update. Surely someone would notice blurriness in the newer thumbnail. - ZS 14:34, July 16, 2010 (UTC)
 * There is very little blurriness in the second picture, it's only noticeable if you specifically look for it. The second image is half the size of the first, so I suppose that's where the quality loss comes from.--IcecreamKitten 14:42, July 16, 2010 (UTC)


 * The images are only different in size by the width of a pixel, and I merely brought them up to prove a point on how new JPG thumbnails generated after the update are now consistently saved in the same poor quality. It may not be noticeable in higher resolutions, but with thumbnails of complex images or smaller thumbnails, you'll find that the degradation affects illustration; even the preview lightboxes generate thumbnails through the same method, which means the high quality original is tucked away in the image page, where it is least likely to be accessed thanks to the image lightbox update months ago. What I want to know is why adapted thumbnail quality was dropped in favor of a inferior setup, and what can be done about it. - ZS 15:07, July 16, 2010 (UTC)


 * As evidence to the above, here is a new thumbnail 250px in width generated from Wikia alongside what the thumbnail should appear prior to the update if Wikia adheres to the original's image quality. - ZS 15:19, July 16, 2010 (UTC)
 * The issue is there, even if it is very minor. To pursue this further, I'd suggest you contact Wikia with reference to this forum page about the bug -- Random Time  15:37, July 16, 2010 (UTC)
 * Seriously, I practically licked my screen looking for differences and saw maybe 5 pixels change. And as Randomtime suggested, even if we agreed with you we couldn't do anything about it. -- Fandyllic  (talk &middot; contr) 10:20 AM PST 16 Jul 2010
 * I can see the difference. :P The generated thumbnail is clearly rougher- with an almost pixelated appearance instead of smooth transitions between colors. However, this isn't something just caused by the gallery update. I have noticed poor quality in jpg thumbnails on Wikia for a long time, and I actually think it is more noticeable in larger images. In most cases any jpg I upload is automatically reduced in quality from the get-go, even if the image file started out perfectly clear and unpixelated on my computer. For example, here are some images that make it more obvious:
 * JPG versions: Full size (slightly pixelated), The generated thumbnail (8px smaller and definitely rougher- especially around the edges of letters and the little girl's head)
 * PNG versions: Full size (no pixelation at all), Generated thumbnail (8px smaller and marvelously no pixelation)
 * For the record, I have tried viewing these in different browsers and the effect is always the same. I always choose to upload in png format. Jpg just sucks. ~ Gardimuer { ʈalk } 21:18, July 16, 2010 (UTC)


 * Unless you know the compression level the images were saved at, comparing them is pointless and misleading.
 * Saying JPG sucks and PNG is better is mostly only true if you're using transparency... unless you can ensure they were using very similar compression quality when saved. Also, PNG tends to be lossless, so it should be better quality, but may have a much bigger file size and load slower. For fast loading and file size savings, especially on the web, JPG is better than PNG if you don't need transparency. -- Fandyllic  (talk &middot; contr) 4:56 PM PST 16 Jul 2010