Saturation adjusting causing visible blocky artifacts

[killerteengohan]

I have source where half of the parts the saturation and colors seem way overblown or too strong for me. Especially the blue color and orange color. Roughly half looks great, but half the scene changes are way too strong for me.

Here are a couple 1080p screenshots showing the colors.

https://forum.videohelp.com/images/imgfiles/LbQPbd9.png
https://forum.videohelp.com/images/imgfiles/l0E1vlb.png
https://forum.videohelp.com/images/imgfiles/csDcYdf.png
https://forum.videohelp.com/images/imgfiles/e3VDuwL.png


Any time I try to lower the saturation, it certainly fixes the overly bright eyesore colors, but it's adding in or making blocky artifacts not previously visible, ruin the picture.

Here is a before and after the saturation adjustment comparison. (Click on image or use keyboard arrows to change pictures back and forth)

https://slow.pics/c/lMCWhLvg (Look at the blue mailbox)
https://slow.pics/c/Sh8EfdcS (Look at the blue sky)


I tried using both tweak, and smoothtweak filters separately. They both cause this to happen.

tweak(bright=0.97, cont=1.00, sat=1.00, coring=false)
smoothtweak(saturation=0.97, brightness=0, contrast=1.00, dither=-1, interp=0, limiter=false)


Do you have any suggestions on things to try to help with the overly strong colors?

[killerteengohan]

I just noticed if I lower the saturation even more down to something like smoothtweak(saturation=0.92, brightness=0, contrast=1.00, dither=-1, interp=0, limiter=false) that doesn't seem to happen on the bright blues anymore.

The mailbox looks so much better.
https://slow.pics/c/I9CK673W


In fact I found some parts where the blue sky in the source already had a bunch of those blocky artifacts, and lowering the saturation down to about 0.92 seems to get rid of a lot of them.

Have a look.
https://slow.pics/c/x9bEBDNq

It looks less saturated than I would like though. I was trying for 0.96-0.97 area.

[jagabo]

I have source where half of the parts the saturation and colors seem way overblown or too strong for me. Especially the blue color and orange color. Roughly half looks great, but half the scene changes are way too strong for me.

Are you using the correct color matrix to convert to RGB?

[killerteengohan]

I'm not converting to RGB in my script, I am leaving it the same as YUV source material. I do not wish to convert it to RGB, and don't know why I would want to.

I literally have done nothing but try to lower the saturation with tweak or smoothtweak and I am having that blocky artifact problem.

[jagabo]

You're implicitly converting to RGB when you see the video on-screen or creating PNG images.

I don't really see any additional blockiness in your samples. The reduced saturation looks a little noisier though. Also, as you reduce saturation you get fewer and fewer different colors. That will make posterization more visible.

[killerteengohan]

I don't really see any additional blockiness in your samples. The reduced saturation looks a little noisier though. Also, as you reduce saturation you get fewer and fewer different colors. That will make posterization more visible.

It's pretty hard to miss that blockiness I am talking about on the blue colors. Maybe it's actually called posterization? I will remember that name. It's quite visible.

I tried a denoiser and gradfun2 just to see if they would help. They didn't really have a huge effect on it. I don't want to do those to the video if I don't have to, but I at least gave them a try to see what would happen.

Lowering the saturation to 0.90 actually makes some of it nearly invisible or gone. Almost as if it fixed it.
https://slow.pics/c/x9bEBDNq

They appear to be going away, or not appearing like they were when the saturation is dropped to 0.90 instead of 0.97.

[killerteengohan]

I spent about an hour playing with options and I found one that works pretty well. I ended up just lowering the saturation much more than I wanted to. It was fixing the issue but then darker areas/colors were getting it.

I found something called lmode 1 which "limits conversion on dark areas (for luma) and on low saturated areas (for chroma)". That actually greatly lessened it appearing in dark areas, and increased the look of the overall saturation a bit more from leaving darker areas alone more when lowering the saturation. The saturation got lowered more than I wanted, but the lmode left more of it in tact to an acceptable level.

smoothtweak(saturation=0.92, dither=-1, interp=0, limiter=false, lmode=1, limitstr=40)


I think it did a pretty nice job. It's not 100% perfect, and some dark areas still have a tiny bit left, but it is a very acceptable middle ground and without the source to compare you probly wont notice the very little that did get left.

https://slow.pics/c/I9CK673W (Mailbox looks much better)


If you look here, there's a very little bit appearing where the sky and treetops meet in the very middle, but it's so much better than it was when doing it without the lmode.

Without lmode 1
https://slow.pics/c/Sh8EfdcS

With lmode 1
https://slow.pics/c/zbnCXrIq

[Selur]

you might want to try https://github.com/Asd-g/avslibplacebo and some of the models from https://upscale.wiki/wiki/Model_Database, there are quite a few models trained for old cartoon stuff.

[jagabo]

Try GradFun3(), included in the Dither Tools package.

http://avisynth.nl/index.php/Dither_tools

Increase thr to 0.70 or higher. Unfortunately, higher values of thr will obliterate low contrast detail too. You may need to use a mask to limit the filter to bright blue areas (or whatever is appropriate).

[themaster1]

Try the filter for virtualdub called "rgb equalizer eq" you can work on specific frequencies (up to 9 i think), work on sat, tint etc... Can also work on secondary colors

[Skiller]

It looks intentional to me.
I wouldn't try to fight it.