Avoiding line thickness when coloring line/shadow

[NathanOtano]

Hey!

I often need to colorize my lines, not only for specific types of animation without lines but also for the limits of my shadows. And to inbeetween it correctly, I always use lines and not something like filled strokes.

The problem is that the black line we see, when colored in the same color than the color used to fill the area, isn't really the contour of the silhouette. If fact the character is more fat, it bumps the contour because of the thickness of the line. Same for the shadows.

In vector programes, we can desactivate the line to have the color stopping at the middle of the stroke, so no problem with the thickness. With tvpaint i have two options : keeping the line and coloring it, resulting in a bumped figure, or removing the line completely and using only an aliased STG layer, resulting in n on accurate lines of contour and separation lines in my animation.

What i would like to try is a "line colorize" mod that also uses alpha. Like when i have a line beetween two colors, they both expands. So if i have a line beetween my character and the background, i'd like it to be half alpha/half color to have a good silhouette.

What i usually do is i use the mechanical pencil to avoid having a thick line, it's okay except for really tiny animation, but it's really difficult to clean an animation with it (and in fact it's a pain to have a beautiful aliased contour with ctg layers and with the line colored in the same color).
I was also thinking about using the "erode" option but it's more like a D system haha

If somebody have a solution

EDIT : Joined a file to be more precise with exemples.

The three first exemple are compared to the drawing with the line. The first exemple without line is with colorized lines, the second exemple il kind of what i need and i used the erode FX to reach the middle of the stroke, and the last one is the CTG layer aliased removing the line. And after that you see the tree exemples one after another to compare.

I can become really obvious with the thickness on an arm or a finger, we can really quickly get off-model.

[Elodie]

That's an excellent idea, thank you for your explanation ! However, I must admit I have no idea if it is possible to do.

[Peter Wassink]

so what is wrong exactly with erode?
i'm afraid i don't quite follow you.

[NathanOtano]

Erode has a fixed thickness, not my lines. Also i lose my sharp edges. It's not a problem with an algorythm like line colorize, more professional than a system D method. Using the alpha outside seems to me a better somution. Also for spmethong lile a shadow, with erode I'll have a gap beetween the border of the shadow and the outside line.

But yeah erode seems like a temporary solution. I have to admit I always avoided this solution by fear of problems, and just tried it while posting my exemple.

[Fabrice]

Erode has a fixed thickness

But the fact is that Line-Colorize too (the parameter is a radius).

So it's probably possible if we rethink the FX to work with the alpha chanel, but we need to spend some time on it to re-develop it. I have added it to the TODO list anyway.

Maybe can you add an effect in the FX Stack like ColorKeyer to remove the unwanted pixels ?

[NathanOtano]

Yay! Thanks.

Yes but a radius with alpha on one side and color on the other side should work.

The colorkeyer will leave aliased pixels, no? I don't see how it can do the job.

[NathanOtano]

Maybe can you add an effect in the FX Stack like ColorKeyer to remove the unwanted pixels ?

Oh I think i understand now. Using a specific color instead of my transparent background i can then use it instead of the alpha channel with my FX line colorize. Then I just have to use the color keyer to remove it from my line. I think I already thought about that then completely forgot it.

Thanks!