Possible alternate colorspaces for video game palettes.

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psycopathicteen
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Possible alternate colorspaces for video game palettes.

Post by psycopathicteen » Wed Feb 24, 2016 11:05 pm

I was thinking about colorspaces today, and I came up with a decent idea for a color space that can easily be converted to low-bit rgb, that should be a little more visually uniform than rgb.

I think I'll call it Yab, just because the Y works like the Y in YUV and YIQ, and the A and B work sort've like the A and B in Lab. So here's my formula.

R = Y + 2a + b
G = Y - a
B = Y - 3b

Any advice to improve upon this. I'm thinking there should be a way to compensate for the not-so-predictable luminance value of highly saturated colors.

lidnariq
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Re: Possible alternate colorspaces for video game palettes.

Post by lidnariq » Wed Feb 24, 2016 11:21 pm

This doesn't really look all that much more useful than RGB?

Here's a simple cube, 0≤Y≤7, -4≤a,b≤3:
yab.png
yab.png (615 Bytes) Viewed 5660 times
Lots of out-of-gamut colors too.

No yellows, and lackluster reds and purples.

Sik
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Re: Possible alternate colorspaces for video game palettes.

Post by Sik » Wed Feb 24, 2016 11:30 pm

Maybe A/B range from 0 to 7, not -4 to 3?

psycopathicteen
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Re: Possible alternate colorspaces for video game palettes.

Post by psycopathicteen » Wed Feb 24, 2016 11:39 pm

Or try -7 to 7. BTW, why is everything so dark?

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Dwedit
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Re: Possible alternate colorspaces for video game palettes.

Post by Dwedit » Thu Feb 25, 2016 10:58 pm

Sounds very similar to YCgCo, but not quite the same.
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psycopathicteen
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Re: Possible alternate colorspaces for video game palettes.

Post by psycopathicteen » Fri Feb 26, 2016 10:29 am

Dwedit wrote:Sounds very similar to YCgCo, but not quite the same.
I never heard of that before, but it sounds awesome.

psycopathicteen
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Re: Possible alternate colorspaces for video game palettes.

Post by psycopathicteen » Fri Feb 26, 2016 6:33 pm

I made a 12-bit YCoCg color palette. It's cool how it ended up being exactly 1024 colors. That means if I make a 15-bit version, it will come out with 8192 colors.
Attachments
YCoCg.png
YCoCg.png (2.55 KiB) Viewed 5518 times

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Drew Sebastino
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Re: Possible alternate colorspaces for video game palettes.

Post by Drew Sebastino » Fri Feb 26, 2016 8:09 pm

I always wondered how having 6bit RGB with 2 extra bits to reduce the value of the color for every channel. Because your eyes are supposedly better at seeing shades of color than different colors or something like that, I wonder if it might even look better than 9bit RGB despite only being half the colors.

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Re: Possible alternate colorspaces for video game palettes.

Post by tepples » Fri Feb 26, 2016 8:46 pm

That's a form of RGBI, with 2 bits per channel. It's the componentwise sum of the Cartesian product of four 2-bit palettes:

Red: #000, #400, #800, #C00
Green: #000, #040, #080, #0C0
Blue: #000, #004, #008, #00C
Intensity: #000, #111, #222, #333

Fortunately, GIMP makes componentwise sums easy using the Addition blend mode.
Attachments
The four subpalettes
The four subpalettes
layers.png (738 Bytes) Viewed 5494 times
The palette
The palette
added.png (1.42 KiB) Viewed 5494 times
Parrot in RGBI2222. Left: not dithered; right: Floyd-Steinberg dithered.
Parrot in RGBI2222. Left: not dithered; right: Floyd-Steinberg dithered.
parrot.png (31.01 KiB) Viewed 5494 times

Sik
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Re: Possible alternate colorspaces for video game palettes.

Post by Sik » Sat Feb 27, 2016 6:01 am

May as well compare it against my colorspace:

Image

RGB 3.3.3, but red and blue share the LSB (so it fits in 8-bit). I came up with it because I honestly hate how little resolution blue has in RGB 3.3.2, which wouldn't be much of an issue except because it seems new "retro" hardware insists on using that (argh!).

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Drew Sebastino
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Re: Possible alternate colorspaces for video game palettes.

Post by Drew Sebastino » Sat Feb 27, 2016 8:08 am

I thought I'd try seeing how Sik's palette looks:
Sik's Palette.png
Sik's Palette.png (13.58 KiB) Viewed 5439 times

zzo38
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Re: Possible alternate colorspaces for video game palettes.

Post by zzo38 » Sat Feb 27, 2016 11:42 am

I thought of a different kind of colorspace: 3-bits high-voltage, 3-bits low-voltage, 3-bits phase. The phase only covers half, because you can get the rest of the phases by inverting it which is done by switching the voltage. If high-voltage and low-voltage is same then the picture will be gray.
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lidnariq
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Re: Possible alternate colorspaces for video game palettes.

Post by lidnariq » Sat Feb 27, 2016 11:52 am

Espozo wrote:I always wondered how having 6bit RGB with 2 extra bits to reduce the value of the color for every channel.
tepples wrote:It's the componentwise sum of the Cartesian product of four 2-bit palettes:
I assumed that Espozo meant something with a multiplier, not RGBI.

Here's the equivalent palette where I parse the last two bits as a all-channels multiplier that ranges from 1 to 4:
rgbmult.png
rgbmult.png (1.24 KiB) Viewed 5406 times
It's really lacking in pastels, though, so the parrot doesn't look so good:
left: plain<br />right: floyd-steinberg dithering
left: plain
right: floyd-steinberg dithering
rgbmultparrot.png (29.77 KiB) Viewed 5406 times

Sik
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Re: Possible alternate colorspaces for video game palettes.

Post by Sik » Sat Feb 27, 2016 11:56 am

Actually his description sounds more like reverse RGBI, where I substracts instead of adding (you could achieve that just by passing I through a NOT). But yeah it's not very clear honestly.

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Drew Sebastino
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Re: Possible alternate colorspaces for video game palettes.

Post by Drew Sebastino » Sat Feb 27, 2016 12:16 pm

Yeah, I didn't mean multiplying. I meant what Sik is talking about. I'm not sure how different than would look than tepples's though.

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