AVISynth DeRainbowers causing color/hue changes?

[darkdream787]

I have tried many different derainbower filters for AVISynth and the best 2 that did their job well and damaged the original source least to my eyes was LUTDeRainbow() and Chubbyrain2()
If you know a better derainbowing filter or setting for the 2 I used please feel free to suggest it to me so I can try it.

For some reason every time I use a derainbower they get rid of the rainbows yes but I also notice other color changes. For example the eye color, skin tone, and clothing usually change to a slightly brighter/different shade of color/hue it looks like. Its barely a big change and not too easily noticeable but it seems to do this to the source.

In the end I just want to make sure the coloration stays proper and isn't off during playback.

here are a few screenshots to see what I mean. Chubbyrain2 was used for these screenshots. If you save them both and zoom in on them using microsoft paint or something, then rapidly switch back and forth between the two, you will notice what I'm talking about. Looking at them side by side its kinda hard to tell.


TOP = No DeRainbow Filter
BOTTOM = With DeRainbow Filter


In this one, I notice Kenshins (the guy with the sword) eye color slightly changes and the girl on the right her clothing color changes a bit. There are probly more but thats what I notice the easiest.





In this one it looks like to me that the girls red clothes change color a bit to a slightly brighter/different shade.





I think I just barely notice the hair color change a bit and the wood on the walls change a little in this example.

[poisondeathray]

There is not much you can do about it, short of masking and manual work. It's a common side effect. You screenshots actually aren't that bad, the side effects can be a lot worse

This is how all derainbow filters function: they look at differences between adjacent colors. They cannot distinguish effectively between a small color that patch was supposed to be there vs. a small patch of rainbow. Moreover, most sources you will encounter are subsampled 4:2:0 (low color resolution), so the color borders are not very sharp to begin with . If it detects a false positive with the current settings, then it may replace the color that you want with some other color you don't want. But if you adjust the threshold settings lower, it may miss rainbows that would otherwise be detected

[darkdream787]

There is not much you can do about it, short of masking and manual work. It's a common side effect. You screenshots actually aren't that bad, the side effects can be a lot worse

This is how all derainbow filters function: they look at differences between adjacent colors. They cannot distinguish effectively between a small color that patch was supposed to be there vs. a small patch of rainbow. Moreover, most sources you will encounter are subsampled 4:2:0 (low color resolution), so the color borders are not very sharp to begin with . If it detects a false positive with the current settings, then it may replace the color that you want with some other color you don't want. But if you adjust the threshold settings lower, it may miss rainbows that would otherwise be detected

I see... well then I guess I didnt do too bad on it afterall.

Do you have any idea why Chubbyrain2 does this to the video when its switching scenes or moves rapidly?



It seems to screw up the deinterlacing or something. LUTDeRainbow and the original dont do that.

I put it before the ivtc in the script and it does that to the video. When I try to put it after, I always get an error and it wont work so I guess I have to stick with putting it before ivtc.

I dont want those in the video so Ill probly stick with LUTDeRainbow at this rate.

[poisondeathray]

They all give some sort of problems. Either use a different filter, different settings, or combination (e.g. using trim)

There is no reason you can't use it after IVTC (even though they usually work better before). What was the error message ?

[darkdream787]

They all give some sort of problems. Either use a different filter, different settings, or combination (e.g. using trim)

There is no reason you can't use it after IVTC (even though they usually work better before). What was the error message ?

It just keeps saying something about

Megui encountered a fatal error and may not be able to proceed. Reason: the file cannot be opened.
Error Message for your reference: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

Usually when I see that error (Ive seen it once or twice before in the past) just restarting the computer gets it to stop but this will not stop and only shows up when I move it after the IVTC. It works fine when when I move it before the IVTC.

[sanlyn]

I see these effects as well, not just with derainbow filters (thanks to pdr for explaining). There's usually a final levels and color fix as a last step. In the examples you posted, some elements don't look quite "correct"' the filtered versions have lower gamma and brilliance than the originals. With many objects it's difficult to tell what's "correct" anyway. For someone wearing white or gray clothing, you know that "white", "black" and "gray" are definite colors with definite RGB characteristics (depending on lighting effects). But a green dress, a purple robe...? Who knows what the exact hue should be? Most colorists would opt to make blacks, grays and whites closer to accurate hues (this doesn't always work, but it usually does). If you can get those 3 elements in line, other colors should fall into place.

With the examples posted below, the basic change was lowering gamma but heightening contrast and midtones. The only white is in the eyes, but no pixel there could ever be pure white. I aimed for RGB 200 or so -- RGB 235 is usually too bright. The differences are subtle but visible. With gamma too high, the darker tones tend to look a bit foggy and the overall color balance looked too red. You can see that with colors like this, many choices are purely arbitrary. Often it depends on what you're happy with.


[Attachment 14116 - Click to enlarge]

[Attachment 14117 - Click to enlarge]

[themaster1]

Try this to remove rainbows:
pointresize(last.width*2,last.height*2)
mergechroma(RemoveDirtMC,0.80) #
pointresize(last.width/2,last.height/2)

It work great on cartoons

download removedirtmc from here: http://www.mediafire.com/?barrrmcvxv81n9g