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


 * JPG only sucks if you save them in high compression (which leads to degraded image quality at the expense of lower filesize), something that is all too common among many JPG users. Saving JPG in low compression (80% quality) or better is actually the best that the format can be to the quality of PNG images, and I've been doing so for a long time with good effect. But in this case, the new batch of thumbnails generates resized images with a poor 50-60% quality but saves them in the same 80% quality of the original, which is baffling and a waste of space. BTW, I've notified a Wikia staff regarding this. We'll see how this turns out. - ZS 09:58, July 17, 2010 (UTC)


 * Thanks for the track down work ZS. Hopefully it was all a result of just miscommunication inside Wikia somewhere. I hope they communicate better internally than they do with their user base, but one never knows. -- Fandyllic  (talk &middot; contr) 3:52 PM PST 17 Jul 2010

Here's another example, I now see why this is such a big deal:
 * Older thumbnail <-> Newer thimbnail

You can clearly see the huge detail loss on the crystal dome. As that area of the image is the most important part (being the most noticeable detail of my new skin background), this "feature" is really disappointing. I really hope they revert the thumbnail generation to what it was a while ago. --IcecreamKitten 08:43, July 18, 2010 (UTC)


 * The more I see people's examples, I'm thinking this problem might be browser related. I don't see the detail loss between the two examples (of course being mostly dark blue doesn't help see the difference). Which browser are you using, IcecreamKitten? I'm using FireFox 3.6.6 on Mac OS X. I will also see if I can see a difference on FireFox and IE 8 on my Thinkpad at work and report the results on Monday. -- Fandyllic  (talk &middot; contr) 10:17 AM PST 18 Jul 2010


 * I use 3.6.6 on Windows Xp SP3. I don't think it depends on the browser, the new thumbnails simply seem to use much higher jpeg compression. If you look at the size of my older pic, it's 234KB, the new one is only 82.2KB. If it does depend on browser or something, here's a cropped version of them next to each other, so you can see what I'm talking about.--IcecreamKitten 05:28, July 19, 2010 (UTC)


 * Well, if it isn't the browser, then it may be something configuration specific, because I see no differences between
 * Older thumbnail <-> Newer thimbnail
 * And they don't match your cropped example for me. I've looked at this now on Firefox 3.6.6 on Mac OS X 10.5.8 and Windows XP SP3. -- Fandyllic  (talk &middot; contr) 3:38 PM PST 19 Jul 2010
 * Looks like it was a cache issue. Now they look the same to me as well. --IcecreamKitten 13:57, July 20, 2010 (UTC)

Or... just maybe... it was a problem on the servers, and we've been trying to fix it this whole time, and all the variances in the reporting above have been from us constantly tweaking it trying to find balance in speed and quality? The techs think they got it at a stable point now. Can everyone double check their "bad" images? --Uberfuzzy 08:53, July 21, 2010 (UTC)


 * Leaves me to wonder what tweaks were being made and for how long, because I've notice little changes on thumbnails between October 2009 (when the quality of a new thumbnail is based on the quality of the original) and the July 2010 gallery updates. And no, there has been no improvement yet; I'm still seeing very visible artifacts on newly generated JPG images. - ZS 13:54, July 21, 2010 (UTC)

Newly generated thumbnails, regardless of the quality of the original, appear to be of fairly good quality as of now. Further tests will be made, but this problem appears to be addressed. Good job here. - ZS 18:56, July 23, 2010 (UTC)