[theora] NHW Image codec - higher quality settings

Raphael Canut nhwcodec at gmail.com
Thu Jul 11 09:39:45 PDT 2013


I have just added a higher quality setting for the NHW codec (-h3, +4/5Ko),
with extended residual coding on 512x256 wavelet image and more higher
wavelet coefficients.This setting has more precision.

I have also tried for the -l3 lower quality setting to raise the
quantization from 0.77 to 0.79, and then remove 1Ko with a fast denoising
(exp, actually I use data computed during pre-processing function in the
encoder, and so this simple denoising is at nearly no extra computational
cost).The -l3 setting would have then a little more precision, but don't
know if it is better (would still have to better select the wavelet
coefficients...).Any comment is welcome.

I have updated my demo page: http://nhwcodec.blogspot.com/ .

Many thanks,

2013/7/3 Raphael Canut <nhwcodec at gmail.com>

> Hello,
> Just a very quick message to let you know that I have added a higher
> quality setting (-h2, +10Ko) and I have added now residual coding on the
> 512x256 wavelet image for the higher settings.Precision is a little
> better.-I also still apply the post-processing function on the 512x256
> wavelet image for now.-
> Here is the link for the binaries (as I can not link them in my blog for
> now):
> https://docs.google.com/file/d/0B9F8eU1TkGfiVDdFZkpWd3I2ZDQ/edit?usp=sharing
> For the lower quality settings, will have to improve the -l3 setting
> first, raise the quantization to something like 0.82 for example for -l3
> and -l4 settings, and better select/remove the wavelet coefficients.
> Many thanks,
> Raphael
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