NHW - a free image codec

[nhw_pulsar]

Hello,

Just a very quick message to let know those who followed NHW, that the last version (v0.3.1+41) has now a good precision, in the sense that NHW image correctly resembles to the original image (for the developed -q9 to -q23 quality settings), while always keeping NHW efficient neatness.

So yes now it could be worth to adapt NHW to any image resolution. For me the best solution would be to process on the whole image dimensions, but it's really the bigger and harder to code. Another approach is the one of Martin, a great programmer and friend of mine, he has adapted NHW to 8x8, 16x16, 32x32, 64x64, 128x128, 256x256, 512x512 square sizes and he has then coded a very first (unoptimized) version of NHW that works with any image resolution by decomposing the image with these square sizes (prioritizing the largest square size first). The problem with this latter solution are the blocking artifacts (with a wavelet codec) but I have been told that deblocking filters could be quite efficient....

For now with my health, I will quietly continue to improve NHW precision, but maybe in the second half of 2026 if I am better, I will think about these solutions to adapt NHW to any image resolution, if I am alone, I think I will clearly choose Martin's solution because it is by far the fastest to deploy...

Cheers,
Raphael

[nhw_pulsar]

Hello,

Just a very quick update, as I think I'll release v0.3.2 in February, I wanted to make then a complete neatness study with objective nhw_neatness_metrics, but the new v0.3.1+42 version has (quite) worse neatness scores than v0.3.1+41, as reported by nhw_neatness_metrics, but I find that v0.3.1+42 has a better visual quality than v0.3.1+41, notably a better precision, it resembles more to the original image, so I didn't find for now a perceptual quality metrics that reflects visual quality according to my criterias and eyes...

Cheers,
Raphael

[nhw_pulsar]

Hello,

I am still thinking about Martin's (square) tiling solution for coding NHW to any image resolution, there are also some strong advantages, it is notably very more multithreading-friendly, SIMD-friendly, cache-friendly... but a very important thing is to know if we can design an efficient deblocking filter for my wavelet blocking artifacts, as I have hardly no knowledge in deblocking filters technology, it seems a very big investment and energy for me now...

Else I am ultra slowly working on NHW currently, but I hope that the next incremental improvement of v0.3.1+42 will lead to v0.3.2 version, hopefully with a real competitive precision with AOM and MPEG codecs, while still keeping NHW neatness which is a strong advantage for me...

Cheers,
Raphael

[nhw_pulsar]

Else I am ultra slowly working on NHW currently, but I hope that the next incremental improvement of v0.3.1+42 will lead to v0.3.2 version, hopefully with a real competitive precision with AOM and MPEG codecs, while still keeping NHW neatness which is a strong advantage for me...


Hello,

Just a very very quick update, I have released v0.3.1+43 version, at very first sight, I am satisfied with precision, so normally I'll see if I make other precision improvements but I think I'll transform this version into v0.3.2 later this month.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly, I have released v0.3.1+44 which is better, I am waiting for releasing official v0.3.2, but I am sorry and I will get some anger, but I think I won't accompany v0.3.2 with a neatness study, as my nhw_neatness_metrics doesn't reflect for me image quality and what I call "neatness".For example, you can have a degraded image and sharpen it, my nhw_neatness_metrics will have very good score whereas the image looks horrible...

Cheers,
Raphael

[rwill]

For example, you can have a degraded image and sharpen it, my nhw_neatness_metrics will have very good score whereas the image looks horrible...

Heh... just like VMAF.

[nhw_pulsar]

Heh... just like VMAF.

Hello rwill,

As I don't know VMAF, thank you for your professional feedback and information.I know that VMAF is largely acclaimed in the video compression community, especially at AOM, but as you point it has its imperfections... Measuring what I call the "neatness" of an image seems very difficult... Is it then offensing to say that VMAF is the less bad of the perceptual metrics?

Cheers,
Raphael

[rwill]

If you are using metrics like VMAF just for your own stuff its probably ok.

The ability to cheat in a metric becomes problematic if different actors start to compete on the basis of the metric. Then such a metric cannot be trusted. Thats why PSNR is so robust, you cannot cheat that one.

[nhw_pulsar]

If you are using metrics like VMAF just for your own stuff its probably ok.

The ability to cheat in a metric becomes problematic if different actors start to compete on the basis of the metric. Then such a metric cannot be trusted. Thats why PSNR is so robust, you cannot cheat that one.

Yes that's right you can not cheat PSNR, but I really can not explain why PNSR can rate high some images that have not a great visual quality, and reversely...

[nhw_pulsar]

Hello,

Just a quick update, I think we can add a 10th element in the weight sequence to improve NHW precision and image quality, but currently I am too tired and it's too boring to test all the possible weights combinations (and there are millions of combinations), and I don't have the formula to derive the best weight sequence, so I must test currently each sequence combination with my eyes on different images...

However, v0.3.1+44 has for me an OK precision, and a better neatness than MPEG and AOM codecs, so I think, if I don't resume work on NHW in the meantime, I'll silently transform v0.3.1+44 into official v0.3.2 version next week, neatness will be still the strong point of NHW...

Cheers,
Raphael

[nhw_pulsar]

Hello,

I've finally improved the weight sequence (to the 10th order), so I have released v0.3.1+45 which is better, -as said, I'll release v0.3.2 next week-.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Before v0.3.2, I have continued with the new v0.3.1+46 to improve the weight sequence (to the 11th order now).

Cheers,
Raphael

[nhw_pulsar]

Hello,

Just very quickly, I'll finally wait before releasing v0.3.2 to determine if I can level up the weight sequence to the 12th order, for a better image precision.I think and hope that the next iteration of the weight sequence order could have a competitive precision with AOM and MPEG codecs (however I can not test AV2- and ECM- intra).

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly, I have released v0.3.2 with an improved weight sequence up to the 12th order, for a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Following the weight sequence improving, I have gone up to the 13th order with v0.3.2+1.

I hope that I will be able to continue to work on the weight sequence orders in the next weeks despite very bad health...

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly, I have continued to improve the weight sequence to the 14th order. v0.3.2+2 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly, I am still at the 14th order for the weight sequence but I have fine-tuned it. v0.3.2+3 has then a better precision.

It is becoming damn hard to test all the weights combinations...

Cheers,
Raphael

[Selur]

So, no news about allowing custom resolutions and nothing anyone seems to be interested in aside yourself.

[rwill]

Hey I was just about to start a bet on Polymarket to which order he can get his weight sequence before someone interrupts his solo post streak...

[nhw_pulsar]

Hello Selur, hello rwill,

Concerning custom resolutions, I don't have looked again at square tiling solution (up to 512x512 tiles) because I have to design a very efficient deblocking filter as again with my wavelet filter design I find that there are quite important border artifacts... so it's a little "blocking" point for me now because designing such a deblocking filter is a very big investment... a litttle too much for me at now...

Yes the industry is not interested in NHW because I would think they estimate that AVIF and VVC intra for example have more precision, they resemble more to the original image, but with the nhw_kernel weights fine-tuning, I am trying to change this, personally I also don't know to which order I can get the weight sequence, but it seems that there are some weight sequence combinations that give a very good precision to NHW, but again I don't have the mathematical formula to derive an optimal weight sequence, so it's a hell of work to visually test a lot of weights combinations...

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I have continued to improve the weight sequence, v0.3.2+4 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I have added a weight parameter ponderation in the weight sequence, v0.3.2+5 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, after fine-tuning the t1 weight parameter, I am now fine-tuning the also important t4 weight parameter. v0.3.2+6 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I am continuing to fine-tune the t4 weight parameter, v0.3.2+7 has then a better precision.

NHW_Neatness_metrics can be lower for some images, but I find that visual quality is still there.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Ultra quickly for those interested, I have continued to fine-tune the weight sequence with a better t1/t4 balance. v0.3.2+8 has then a better precision.

NHW_Neatness_metrics numbers are also better for this version.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Ultra quickly for those interested, I am continuing to fine-tune the t1 and t4 weight parameters of the weight sequence. v0.3.2+9 has then a better precision.

Cheers,
Raphael

[Selur]

So, no news about allowing custom resolutions and nothing anyone seems to be interested in aside yourself.

[nhw_pulsar]

So, no news about allowing custom resolutions and nothing anyone seems to be interested in aside yourself.

Hello Selur,

Thank you however for following my progress.

Concerning custom resolutions, I said in a previous message that I wanted to focus in the first half of 2026 to improve NHW precision and then in the second half of 2026 code NHW to any image resolution with square tiling solution (up to 512x512), but I realize it's a very big investment, the big problem is that I fear to not have the energy to first design the mandatory big wavelet deblocking filter...

Cheers,
Raphael

[Selur]

Hi,
I guess, to everybody else, it looks like:
a. you got a non-describable/documented metric you call "NHW_Neatness_metrics".
b. since the start, you write that you are increasing it and the 'NHW precision'.
This is like you reporting every few days that you are doing something non-consequential.
Since there is nothing tangible to it, these updates simply seem like a waste of time.
Especially since you write that you have health issues, it seems like it would be better if you spend your energy on living (maybe getting better).
That said: If posting these (to others seemingly useless) updates, helps you in that process: Keep it on.

Cu Selur

[nhw_pulsar]

Especially since you write that you have health issues, it seems like it would be better if you spend your energy on living (maybe getting better).
That said: If posting these (to others seemingly useless) updates, helps you in that process: Keep it on.

Cu Selur

Hello Selur,

Thank you.Yes I have health issues, and working a little daily on my codec, and posting on the forum when I have an improvement, help me keep contact with the compression community (few people follow my updates) and also be better...

But again some people appreciate my updates, some others hate... so I will completely comply to the instructions of a moderator concerning my posting on the forum if there is a problem.

Cheers,
Raphael

[lvqcl]

(few people follow my updates)

I want to see these people...

[nhw_pulsar]

I want to see these people...

I just mean when I post my updates on the forums, then I have a little visit on my demo page and a few clones on my GitHub...

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I have continued to fine-tune the t1 and t4 weight parameters of the weight sequence. v0.3.2+10 has then a better precision.

NHW_Neatness_metrics numbers seem also good for this version.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I am continuing to fine-tune the t1 and t4 weight parameters of the weight sequence. v0.3.2+11 starts to have a competitive precision for the developed -q9 to -q23 compression settings.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, while always fine-tuning t1 and t4 in the weight sequence, v0.3.2+12 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly, I am still trying to improve precision of NHW, that the codec faithfully resembles to the source image, but yes clearly as many professionals stated it here on this forum, the research effort at AOM, MPEG,... is as they have now a very high level of precision, the aim is now to preserve/retain as most as possible fine details/textures/grain... NHW can not compete in this area, so it's clearly a no-go for it...

I tried to compensate this with more neatness of image but the compression bodies are not sensitive to this argument... But it's ok, I'll still try to finish precision of NHW if I can (as it is more and more difficult), but it becomes more and more clear (very sorry) that I will not adapt NHW to any image resolution with square tiling solution (up to 512x512 tiles) in the second half of 2026...

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, still improving t1 and t4 tuning in the weight sequence, v0.3.2+13 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, still improving t1 and t4 tuning in the weight sequence, v0.3.2+14 has then a better precision.

NHW_Neatness_metrics numbers seem good for this version.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I am still continuing to improve the weight sequence, v0.3.2+15 seems to have then a little more precision and so a little better visual quality.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Ultra quickly for those interested, I am continuing to fine-tune the t1 and t4 weight parameters in the weight sequence. v0.3.2+16 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I am still continuing to fine-tune t1 and t4 weight parameters in the weight sequence. v0.3.2+17 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, still continuing to fine-tune t1 and t4 weight parameters in the weight sequence. v0.3.2+18 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I have optimized t4 weight reinitialization. v0.3.2+19 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I am continuing to optimize t4 weight reinitialization. v0.3.2+20 has then a better precision.

I am aware that NHW_Neatness_metrics scores are lower for this new version, but I still find that visual quality is better...

Cheers,
Raphael

[nhw_pulsar]

Hello,

Just an ultra quick update, I am still continuing to fine-tune t1 and t4 weight parameters in the weight sequence. v0.3.2+21 has then a better precision.

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I am still refining t4 weight reinitialization. v0.3.2+22 has then a better precision.

Cheers,
Raphael

[Columbo]

Seems like in 18 years you could have moved beyond 512x512. That's a much more important function than tweaking weights continuously.

[nhw_pulsar]

Seems like in 18 years you could have moved beyond 512x512. That's a much more important function than tweaking weights continuously.

Hello,

Yes the first version of NHW dates back to 2008... and yes this is a mistake but since then I never had the energy to adapt to any resolution (because since longtime I struggle against illness)...

Coming back to NHW, some professionals told me that the codec lacked of precision, but I would find now that latest v0.3.2+22 starts to have a competitive precision...

Cheers,
Raphael

[nhw_pulsar]

Hello,

Just an ultra quick update, I am still continuing to fine-tune t1 and t4 weight parameters in the weight sequence. v0.3.2+23 has then a better precision.

I don't know how far I will be able to push NHW technology to a good precision, but I would find now that NHW precision is competitive, so hopefully I'll release v0.3.3 in the very next months...

Cheers,
Raphael

[nhw_pulsar]

Hello,

Very quickly for those interested, I am still optimizing t1 and t4 weight parameters in the weight sequence.

As I am now satisfied with NHW precision, I have decided to release v0.3.3 release candidate 1.

Cheers,
Raphael