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)