Subject: [video-codec] NHW Project - good quality improvement & new -l14 very high compression quality setting

From: Raphael Canut <[email-masked]>
Date: Wed, 12 Dec 2018 18:28:37 +0100

Hi,

Just a quick message, I am still progressing with very high compression and
I have corrected a processing, so now very high compression (-l10 to -l13
quality settings) has really better precision and so better quality.

I have also released a first draft of a new -l14 very high compression
quality setting.

More at: http://nhwcodec.blogspot.com/

-Just a remark, the entropy coding schemes start to be less efficient at
-l14 very high compression, and we can really improve them and save
bits.For example the coding of the wavelet DC coefficients, wavelet DC
image is far from optimal.I have 4 compression modes for 4 different data
nature for the wavelet DC image, but I just choose the overall best coding
mode for the whole wavelet DC image... this is not optimal, I can really
save bits if for example I split the wavelet DC image in 16x16 blocks, and
give the one appropriate mode to each block, adapted to their nature.-

Again using paq8px compressor, and simply compressing the .nhw compressed
files, we see that we can save 2.5KB per .nhw file...

Any feedback on the new -l14 quality setting and on the quality
improvements is, as usual, very welcome!

Many thanks again!
Cheers,
Raphael