Well, that was a bit more difficult than I anticipated. The first really close guess was by Bodobodo who noticed a slight increase in thumbnail quality. Then WillL and Thomasphoto60 noted similar experiences when finally ChrisKSDF nailed it.
The thumbnail version of all photos have been in the GIF format since the beginning of Airliners.net. Last night, after two days of running the transfer script, thumbnails in JPEG format had finally been made and I were able to update the database pages to link to the JPEG files instead of the GIF files.
What's the point of this then you might ask. Well, first:
Notice the difference? The first file is a JPEG file and the second one (to the right) is a GIF file. The JPEG is generally of much higher quality than GIF.
You should be able to see a clear difference between those pairs. If you don't, you might use ancient or poorly configured hardware (like graphics card and monitor) that can only display 256 colors on your screen. Airliners.net will work great with such settings but you won't experience the photos in full true colors. And forget about trying to upload photos with a 256 color display.
Anyway, the second reason for moving to the JPEG format is size. The JPEG file of the MD-80 in sunset is 3092 bytes and the GIF version is on 15227 bytes. That makes the GIF file close to five times bigger! (about three times bigger is normal though). Using JPEG, pages will load faster and we'll use up less of our limited bandwidth.
The JPEG thumbnail files are saved with a compression of 37 (100 being top quality and biggest file size). Using this compression, there might be cases where GIF files actually look better than the JPEG version although I have yet to find one. PUnmuth@VIE's example above is close. The difference is hardly visible though. If anyone have thoughts on this issue and think we should increase the JPEG quality, please don't hesitate to let me know. If you have examples of files that have decreased in quality since the change to JPEG, please post them here. During a transition period, both JPEG and GIF versions of the thumbnails are located in the /small/ directory.