NEW CLUSTER STUDY THREAD!

[ptoing]

Joe: There are 2.5 approaches as far as I know.

Unstretched:
256 / (number of steps per channel). So for example for 444 you would have 16 steps.
Then you always add that number to get your 16 values. Which means you do not get to the full range of 255 but in this case you stop at 240 or F0. And your legal values for 444 unstretched would be 00, 10, 20, 30 and so on.

Stretched:

This means you expand to the full range of RGB888:

To do this you go: 255/steps-1
This is your base step, and then you multiply that by whatever step you want to get at. So for example if you would take 5 bits, being 32 steps you have 255/31 = 8.225806..... and you wanna know the 8th step you get 65.8064.....

Now this is why I said 2.5 ways. Because when stretching you can either floor (aka always round down) which would give you 65 in this case, or you could round to nearest so that would make it 66.

In Promotion you can set your bits per channel, and in Grafx2 you can set steps. Both have their pros and cons.
With bpc you can do stuff like 232 or 565, with steps you can do 3 steps for which there is no clean bit value. But the Amstrad CPC for example had 3 steps per channel resulting in 27 possible colours.

But if you know how to calculate it it is fairly easy to make small palettes like the CPC one by hand and save them.

I hope this was clear enough, if not let me know.

[Ai]

On bit restrictions: Also why would bit restriction exclude grays?

Well, look at an example, Amstrad CPC:

You have three possible levels of R,G,B : 0, 127, 255. That gets you 3 pure gray levels : black, midgray, white.
There are a few mildly desaturated colors, like 255 255 127, but these certainly are nowhere near gray. For mixing colors in the way helm is talking about, you need relatively desaturated colors. CPC art mostly avoids creative color mixing for this reason.

As you increase the number of RGB levels, more desaturated colors become available: For example, in EGA64, you have 4 rgb levels: 0, 85, 170, 255.
This gives 4 pure greys plus a few 'sort-of-vaguely-grayish-if-you-squint' colors like 170,170,255.

.. by the time you get up to 16 levels / 4 bpc (Amiga), you have a large choice of hues, 16 pure greys and 30 or so off-grays and can definitely do plenty of blending. The majority of colors available are still relatively saturated, though -- I'd say for example that there is not a 'non-oily' caucasian skin tone in a 444 palette -- you have a choice between rather olive and a bit red in the face.


In addition to what Ptoing explained, it's also rather doable to emulate color restriction, if you have to, via hex #RRGGBB codes.
For example, allowing only one of 00 40 c0 f0 for each channel is equivalent to unstretched ega64 -- 2 bpc. amiga / 4 bpc is also easy to remember, it's just 00 11 22 33 etc up to ff (or #00 10 20...f0 if you're going for unstretched).

[ptoing]

Well, not 16 greys, always steps minus 2 since black and white are not really greys and can not be used to buffer anything either.

[Helm]

re: restricted bit palettes for learning: not really, honestly. I would recommend people work with 8bit system specs, of course, but it's not like you can't learn with the c64 palette or the EGA one.  It's more useful for me because I went through a decade of amiga-esque blending and I'm trying to unlearn certain habits and also love game art for being game-arty.

On a more general note, I don't want to add more to my thoughts on cluster theory even if I had something significant to say because even with the last major concept I introduced (the examination of single pixels) there was significant pushback. I feel that there's no real need for a single person to push this envelope when a community says 'uh... nope'. Different people, in the future, fate willing, will contribute more palatable ideas that build on this foundation. The way the cluster stuff has been recombined and streamlined by Cure for example pleases me greatly - as divorced as it can be from any single person's ego, the better.

[ptoing]

Yes, I think everyone should try and take away their own lesson from what cluster theory can do for them. I find myself being a lot more conscious of cluster formations and things like single pixels, but I still use them where I feel they are warranted.

I think it shows quite nicely in my latest bigger piece, which coincidently also is RGB333, since it is Atari ST specs.

[yrizoud]

MCGA screen mode (often called "VGA" 320x200x256) seems to have a precision of only R6G6B6. (64 levels of R G B)
Is there somebody who worked with this mode, who can say if this felt like a limitation in color choice ?

[Ai]

MCGA screen mode (often called "VGA" 320x200x256) seems to have a precision of only R6G6B6. (64 levels of R G B)
Is there somebody who worked with this mode, who can say if this felt like a limitation in color choice ?

Not for color choice generally, but desaturated colors are still a bit lacking -- it was an issue that came up when I was designing the new default palette for OHRRPGCE. I'd go up to about 192 levels of R G B before I'm -really- satisfied with choice of desaturated colors.
It's a pretty mild limit though -- amiga 444 encourages you to be obviously oilpainty in color usage, VGA is just slightly oilpainty, and won't really be a relevant concern for < 10color ramps.

[Helm]

Worth keeping in mind that stellar VGA work did not occur in a 666 bit vacuum suddenly in 1990 or something. The artists that did the best VGA work were trained on previous 8bit machines and more importantly on amiga, on deluxe paint and brilliance and so on, therefore their color choice and technique does not rely on infini-shades and 256 full palette pictures very often. Look at Westwood artwork in particular, most of that stuff happened on amiga first and then got dos ports.

[ptoing]

MCGA screen mode (often called "VGA" 320x200x256) seems to have a precision of only R6G6B6. (64 levels of R G B)
Is there somebody who worked with this mode, who can say if this felt like a limitation in color choice ?

I worked a lot in 555 for GBA and DS stuff, and I never felt like that was a limitation at all.

[Helm]

I agree. 555 might as well be 24bit, as far as pixel artistry goes.