A more generic way to fix color casted line in anime after color correction?

[lansing]

When we finished color correcting some color casted old anime, often the black line art are still not fixed. For example in this image, I got what I want for the color, but the black line art around the skin are still exhibiting the red cast. I can fix this by using some color manipulation programs like 3D LUT Creator, reducing the saturation on those red on the color grid, but it requires manual work and different from image to image. Is there a more generic way to fix this?

https://imgsli.com/MTkwNTg4

[poisondeathray]

Maybe filters with line mask ?

The "fix" doesn't necessarily look great either. You're trading pink/red for green/teal . Around character's right ear looks especially noticable

[hello_hello]

An idea borrowed from jagabo (VideoHelp).

You could warp sharpen the chroma by a fairly large amount. I'd probably warp sharpen the luma a little too, to neaten the lines. If you over-do the chroma sharpening it can leave gaps between the chroma and the lines (although maybe that's only a problem for subsampled chroma), but I think it's okay for your screenshot.

ImageSource("D:\pic.jpg")
ConvertToYV24(matrix="rec709")
C = FastLineDarkenMod4(thinning=0)
MergeChroma(C.aWarpSharp2(depth=5), C.aWarpSharp2(depth=100))
FastLineDarkenMod4(thinning=0)

https://imgur.com/sVMq3ac.png

[lansing]

An idea borrowed from jagabo (VideoHelp).

You could warp sharpen the chroma by a fairly large amount. I'd probably warp sharpen the luma a little too, to neaten the lines. If you over-do the chroma sharpening it can leave gaps between the chroma and the lines (although maybe that's only a problem for subsampled chroma), but I think it's okay for your screenshot.

ImageSource("D:\pic.jpg")
ConvertToYV24(matrix="rec709")
C = FastLineDarkenMod4(thinning=0)
MergeChroma(C.aWarpSharp2(depth=5), C.aWarpSharp2(depth=100))
FastLineDarkenMod4(thinning=0)

https://imgur.com/sVMq3ac.png

iirc that this routine is for fixing color bleed. My problem here is the color casted lines, in my sample the lines are red.

[hello_hello]

There's also what looks similar to chroma bleed around some of the lines. Her mouth, for example.
The lines seem far less red to me, but the green shirt being worn by the person standing behind her.... those lines are dark green.

Were lines always pure black, at least for older animation? I ask, as I'm sure I've got some animation, old episodes of Family Guy probably, where the lines are often a very dark color rather than black. Totally different from the crisp black lines in later episodes. I don't know if it's because the animation style has changed, or if they were put through a damaging process at some stage, or if they were created that way.

[lansing]

There's also what looks similar to chroma bleed around some of the lines. Her mouth, for example.
The lines seem far less red to me, but the green shirt being worn by the person standing behind her.... those lines are dark green.

The chroma bleed was caused by my color correcting program, the dark green line are just artifact on my part.


Were lines always pure black, at least for older animation? I ask, as I'm sure I've got some animation, old episodes of Family Guy probably, where the lines are often a very dark color rather than black. Totally different from the crisp black lines in later episodes. I don't know if it's because the animation style has changed, or if they were put through a damaging process at some stage, or if they were created that way.
The lines from the original cels are usually black. They only repaint the line when there was not enough contrast to differenciate two simular color. For example, and brownish hair with a purple highlight on top.

[shph]

This is a normal "film halation" effect. It is a part of real film look
https://coloristfactory.com/2021/09/05/what-is-halation-why-is-it-freaking-important/
https://thedarkroom.com/what-is-halation/
"Halation is the reflection of bright points of light off of the film base and pressure plate causing a “glow” in the strong highlights on some images. "
In your anime example large bright areas creates orange halation around small black areas. So it is not a bug. It is a part of original film look.
http://thelightfarm.com/Map/BitsAndPieces/28Apr2011/HalationDiagram.jpg