Re: [Tuxpaint-devel] New "Bloom" effect added

[Bill K. <nb...@so...>]

On Sun, Feb 26, 2023 at 03:28:03PM +0100, Karl Ove Hufthammer wrote:
> Bill Kendrick skreiv 07.02.2023 10:43:
> >I got a little obsessed over the "bloom" effect, and was struggling to
> >understand Fast Fourier Transforms to get it done.  Maybe some day.
> >In the end, I brute-forced it and came up with an okay-looking (if not
> >awesome, and not fast) effect.  It's in the Git repo, please try it out.
> 
> I’m sure the math is complex, but at least on my system, it just
> looks like a *very* subtle ‘lighten’ effect.

It's meant to add a fringe around light parts of the image, to
simulate how bright lights affect how things look to a camera or
even to human eyes.

Here's an example where I created a brown background, with a slightly
lighter brown radial gradient, then drew some basic color bars
(white, yellow, cyan, green, etc.).  The 'glow' seen comes entirely
from the bloom effect being applied.

  https://pbs.twimg.com/media/Fp9DImxacAA-Bj2?format=png&name=small

Frankly, I would have loved to implement it using Fast Fourier Transforms,
but _that_ level of math has eluded me so far.


> And at first, I didn’t think it worked *at all*, as the thing I was
> drawing disappeared as soon as I let go of the mouse button. But
> after a bit more testing, I see that it does lighten (non-dark)
> areas somewhat and adds a (too) subtle glow effect.

Okay, I've tried changing "BLOOM_WEIGHT_CONST" from 0.025 to 0.05,
basically doubling it, and it's more obvious, without being too
overwhelming, I think.

-bill!