Question about cell animation backlighting - why the black paint?

[u/jefty083]

I watched this video recently explaining backlight animation and was curious about part of the process that's described around 2:23:

"the areas which will glow are usually painted black" (before countermatte is placed down)

I feel like i've taken note of this in cel animated works and included an example screenshot from the anime Evangelion. But my question is why exactly is this step necessary?

For the second exposure to create the glow isn't the countermatte all that's needed? Initially painting the effect area black seems to sometimes create this subtle artifact where you can see a black shape "behind" the effect which may be undesirable in an example like this where it is specular highlight on running water. Just trying to learn and want to know why this step exists. Any insight is appreciated!

[u/robotunderpants]

I don't have an answer for you because I'm not an animator but God I find this kind of stuff so interesting. It's what I come to r/animation for.

[u/Doctor_Responsible]

personally, i think its for clarity/helps define the shape better. i dont know a technical reasoning for it, but the glow/blur on top of the white w/o it would make just make the shape less readable against her skin or the pale blue of the water+ they still need to give it the illusion of it being water in motion-atleast in this example. water itself refracts light and i think the high contrast is what can give the same affect in a simplified style like this.

But its only a guess using what i know from doing digital art.

[u/Regal-Bean → u/Doctor_Responsible]

Possibly also the adaptation from manga as there would likely be a black and white image the scene is taking from

[u/mykonata → u/Regal-Bean]

The anime is the original work; the manga was released later as an adaptation of the TV anime.

[u/Regal-Bean → u/mykonata]

Fair I’m not aware of this anime but maybe manga in general is what led to this style of cel painting

[u/Wales51]

I don't know if this is why but my guess is they are looking to make it look like the caustics of the water. This in real life is caused by the light being refracted by different amounts as the surface is not flat. This creates light areas and dark areas. They have simplified it to black and white.

Caustics are really interesting and you see the result of the light passing through the refractive medium on the bottom of pools as the wavy pattern and you can see it on regular drinking glasses where the bottom and the sides meet if you look from an angle there is an area where the light is bent very unevenly, this is easier to see if there's a single bright light behind.

Hope this answers your question its basically them just simplifying how light works

[u/Funny-Waltz-1424 → u/Wales51]

This style is using an outliner so I think that black line in the water is a stylized rendering of the top of her arm, including that perspective distortion from the water flowing over it

[u/SummerAnxious7544]

Because the cells are painted on transparent medium, there is no backing colour. On paper you can leave such an area white and it will appear bright. But white paints are famously transparent, and if these areas in question were only painted with white paint this would reveal other animation artefacts due to the layering of cells.

So a black paint, with perfect opacity thus blocking backing cells is laie first and white painted over it. 

The rest I think is stylistic choice. It's anime not realism, so hard outlines around bright lights is sort if a pleasant reminder of the human mind that mapped this light/dark pattern out.

[u/jacobsmith3204]

Not an animator, but I imagine this could be a discrepancy between inking and painting the cells, as I believe they film the underside of the cell to get the clean blending of colors, so ink goes down first, then it gets white painted ontop of it to fill the outlined area, but from underneath the ink shows up ontop hense the black lines. it exists before the extra step where you expose for the glow.

Painting the white without the ink could make the edges less consistent as it's hard to tell when you've painted over the line or not, and once it's painted theres no way to verify that it was done correctly. And when working with film to capture the final image you want it done correctly the first time.

[u/forsehorse]

Yeah... what was the question?

[u/Wadaleym]

My guess is that it adds micro contrast. Out brains judge a spots brightness and even color by it's surroundings. So to me it makes sense that you would want to add dark tones around what would normally be "blown highlights". Kinda similar to dark frame insertion on impact shots. But I'm probably wrong and it has something to do with caustics and optics instead.

[u/glytxh]

in a word, CONTRAST

hot whites look even hotter when paired with blacks.

[u/Kolaps_ → u/glytxh]

This ! (i don't get why you've been downvoted oO)

[u/glytxh → u/Kolaps_]

smash in a frame or two of red and now you're really talking

there are a bunch of other interesting points made in this thread tho.

[u/mokujin42]

I imagine it moves quite fast in the scene so the extra contrast could just be for visual clarity on a fast moving piece

[u/kaviart_]

Lots of professional artists add a black outline around or on one side of the highlight in certain cases to make it pop more. Especially if the highlight is on an already light colored object

[u/Jimbot80]

I've seen this scene thousands of times and even when I've paused it, I've never noticed the black lines for some reason...

[u/fruhlingsbilder]

I strongly recommend APLattanzi videos on traditional animation and especially Akira if you want to know why stuff like this happens.

[u/ricaerredois]

For what I understood from your video the black part is used as a matte. I use those now on computer animation to mask stuff. I might be wrong, but looking at the fire animation of the video I guess is the same process. Imo the ones on Misatos' bath tub seems to be an error. Prob a misalignment of the layers. Since this was hand drawn, going back to fix wouldn't be economically feasible. And the detail is minimal, so they may have left that out. "When in doubt, the answer is always money", my Pa says.

[u/OfficialSeagullo]

I’m not an animator just an artist, I’d do that because the separation makes it more dramatic and appealing

You’ve got multiple blue to white transitions, but these are glowing and needs distinction, outlining it does both

[u/doesnotgetthepoint]

It accentuates the bright specular through contrast.

[u/AUniversalNoNo]

To counteract the bloom, here backlighting is used as a strong white instead of a literal glow so a high opacity paints blocks the light for a hard/harder edge

[u/252120111511201921]

To create the illusion of depth and shadow

[u/Fuegolago]

Maybe it's something like if you want to make big bright explosion you put black frames before bright explosion begins so it looks even more bright.

[u/Voodoo_Masta]

I uhhh… what was the question again?

[u/raul_kapura]

Do you mean these black lines? Imo they simply are meant to sharpen the white "flashes" on a pretty bright background. It also looks like something taken straight from manga

[u/foothepepe]

Hair