I was playing around with this a ton yesterday.

One thing I was attempting to do was create an emoji that only had partial portions that had their brightness maxed, while the rest of the emoji displayed "normally". It turns out this was quite hard to do - most filters or scripts such as the one on this page simply max out the channels, which creates a "fried" look to the image.

Gimp luckily has support for this, but getting an existing image to display the "same" with the new color space proved fairly difficult. I found this curve to be the best starting point, after which I edited things from there manually: https://image.non.io/a3c227d4-56d6-40bd-a898-3879fd062cf3.we...

I used this to create a companion emoji to the :mean-jacob: emoji (https://html.non.io/emoji/mean-jacob.png) my team is quite fond of using (I'm Jacob). I made :angel-jacob:, which has a halo that shines with the brightness of a thousand suns. I don't expect my team will use it, but still it was a fun exercise: https://html.non.io/emoji/