On 6 October 2011 16:41, Tom Gall <tom.g...@linaro.org> wrote: > On Thu, Oct 6, 2011 at 9:30 AM, Christian Robottom Reis <k...@linaro.org> > wrote: >> On Thu, Oct 06, 2011 at 08:44:01AM +0300, Fathi Boudra wrote: >>> On 6 October 2011 00:43, Mans Rullgard <mans.rullg...@linaro.org> wrote: >>> > On 5 October 2011 18:35, Christian Robottom Reis <k...@linaro.org> wrote: >>> >> On Wed, Oct 05, 2011 at 08:09:03PM +0300, Fathi Boudra wrote: >>> >>> Debian/Ubuntu P are going to move to libjpeg8 by default making >>> >>> current package obsolete in the future. >>> >> >>> >> Note that when we asked Darrell about this he questioned the performance >>> >> benefits of version 8. Mans probably knows more. >>> > >>> > There is no benefit to v8. v7 added support for the rarely/never used >>> > arithmetic coding option, left out of earlier versions due to patent >>> > issues. Since nobody uses this mode, supporting it is irrelevant. >>> > v8 only adds some experimental, non-standard coding options even less >>> > relevant to any real-world uses. What is relevant is, however, that >>> > v8 is significantly slower than v6 in the default configuration. I >>> > don't remember if this slowdown was present already in v7. >>> >>> According to Bill Allombert, v8 support more image format and provide >>> a higher image quality. >> >> I really question this statement based on what Mans and Darrell have >> both said (a number of times now). Where is the hard data that shows >> this is true? > > Sounds like there needs to be a discussion with Bill. I would be > interested how he is measuring image "quality.
IIRC v7 or v8 made some changes to the quantisation, which could in theory improve quality at a set target size. I haven't done any tests myself so I can't say if it works as intended. Also, what improves one image might degrade another. On top of that, image quality is very subjective and hard to measure. A change improving a metric like PSNR can very well decrease subjective visual quality. -- Mans Rullgard / mru _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
