On Saturday, October 19, 2013 12:12:14 AM UTC+1, Ralph Giles wrote: > On 2013-10-18 1:57 AM, Yoav Weiss wrote: > Do you have such a sample?
For what it's worth here's an image I made quite awhile ago showing the results of my own blind subjective comparison between codecs: http://www.filedropper.com/lossy The image shows the original lossless image alongside a JPEG, JPEG-XR, JPEG2000 and Web-P version of the image all of which have been compressed to 7.5kb. I used the leadtools compression suite for all images except the web-p one, where i used Google's libwebp. I'll be *very* clear here that I don't consider this image very good proof of how good each codec is, clearly the JPEG compressed image could be optimized more. The lossy compressed images are ordered as JPEG, JPEG-XR, JPEG2000, Web-P with respect to the results I personally came to about their performance, web-p being the best and jpeg being the worst. I did this comparison at every quality level and using many different image sources and found the subjective results were the same. The difference between Web-P, JPEG200 and JPEG-XR can at times be hard to call as it felt like i was deciding which compression artifacts bothered my most personally rather than which image felt closest to the original. What was consistent however was that all the modern codecs seems clearly superior to JPEG, or at best appeared the same as JPEG at higher compression qualities but certainly never worse. What I'm saying is based off my own experiences I'd be shocked if anyone could go through a subjective blind test like this and feel that JPEG was performing better at any quality level or with any images. I'd also agree the points brought up by lept...@gmail.com. I think the actual features supported by the current range of web image formats is quite lacking. It's common on the web for web and game developers to compress photographic images as PNG's because they need transparency. Animated Gif's are also popular for compressing short live action video clips, something the format is terribly inadequate at. Both JPEG-XR and Web-P include transparency + alpha support. Only Web-P supports animation, though I believe animation could be added to JPEG-XR easily http://ajxr.codeplex.com/. The extra color formats supported in JPEG-XR could one day be useful on the web too. Although the benefit of better compression performance in web image formats would have obvious speed benefits, I think the consequences of having such a limited feature set in the current range of supported image formats on the web is holding web developers back far more than file size issues. _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
