Color restricted palettes? (help)

[Slothien483]

Hi there

Just wanted to know something I've been wondering for some time now. Here's the deal : I want to do a piece with color restrictions, with one of those famous palettes I see mentioned everywhere, but I don't know what is the software that has them.

For example, I've seen pieces with "c64 multicolor mode" , "EGA" , "c64 grayscale" , "c64 high res" , etc, color restricted palettes, and I would like to do a pixel art with these, but I dont know what is the software that has them, again.

Thanks in advance!.

[ptoing]

Download this for C64 mcol as well as hires and other stuff, read the internal help that is c64 specific.

http://noname.c64.org/csdb/release/?id=30789

Also,

general stuff about the C64 colours


ZX Spectrum stuff


ORIC stuff (only for the hardcore and/or insane)


Top one is the standard EGA palette which was used on old IBM compatibles and PCs, bottom again is speccy.


Hope this helps.

[Ryumaru]

im crazy and would like to try some oric stuff, but im ENTIRELY confused of the paper and ink thing. would be great if you could explain further oh master of everything pixel, ptoing.

[Xion]

Yeah, got any examples of art made with ORIC? A picture's worth a thousand words.

[Ai]

There is a picture included -- just above the inversion explanation, corresponding to what was explained earlier.
Someone here used to have an ORIC avatar. Try searching for ORIC on these forums.

EDIT: that doesn't find it -- but the guy to ask is Feron, it was his avatar.

A more technical explanation:

Each 6x1 cell takes up 8 bits

012345CI

(C and I are bits 6 and 7 respectively)

Normally (when neither C or I bits are set), the bits # 012345 represent whether the color in that position is paper (0) or pen(1) color. If the C (color change) bit is set,
bit 0 says whether it is the paper or pen color changing,
bits 123 specifies the color to change to,
bits 45I are ignored.
When the C bit is set, 0 (paper) is taken as the mask value for all 6 pixels in the cell.

If the I bit is set, the meaning of bits 012345 is inverted.

[Cow]

Eh? That seems to bring up more questions than it answers.

The ZX Spectrum one looks like fun, I'm gonna try that in a bit.

[Ai]

I only explain things, not answer questions.
Your post did prompt me to notice that the interaction of the C bit and bit 0 was not properly explained, so it's fixed and complete now. In combination with the knowledge that the paper/pen colors are reset to white and black at the start of the line, it is a complete description of the capabilities of the ORIC display.

[ptoing]

Yup what Ai stated is correct, tho I don't think it helps to understand anything better (unless you are a programmer perhaps or know a bit more about bits, bytes and nibbles)

Some ORIC pics:

Here a very simple approach by exocet.
The leftmost column or 6 pixels (the first attribute cell in every line) is left black and he uses it basically to change the paper (foreground colour)


Logo by mooz for the barbitoric demo.
You can see he used mainly white and where he changes colour he always has some black buffer around to ensure there are no problems with the attribute changes.
The white on the very border might look strange, but watched on the real thing (or even emulators), you have a black border around the screen which is afaik not changable in any way.


A pic by some chap called D. Vasiljevic.
Quite effective use of the restrictions imo. He changes both ink and paper, not only paper like most others would do.

[Feron]

My fad-avatar had an oric mode :



My attempt is poor compared to those ptoing posted.  Its a damn hard mode - perhaps ill try it again on a larger scale sometime...

[robotriot]

Here's the KC85 palette and its restrictions:



The left column are background colours, the rest is foreground; 320x256 resolution. The screen is divided in 4x8 pixel rectangles; each rectangle can have one of the 8 background colours, and one of the 16 foreground colours.

Here's my crappy attempt at doing something with that restriction.

[ptoing]

That looks quite hardcore, I think I have to give it a shot. Actually that is easier than C64 hires, 2 colours per 4x8 instead of 8x8 and more colours, sounds good to me, although the colours are a bit eyesore

[Ryumaru]

of course, its the c64. basically every other fixed pallette ever made fails to compare.

[ptoing]

of course, its the c64. basically every other fixed pallette ever made fails to compare.

Well as far as fixed palettes of old 8-bit computers go, yes indeed

[robotriot]

Heh, would be cool to see you do something with the KC85 restrictions, ptoing. After posting this I tried to improve on the first attempt, but this didn't turn out so great either. Don't know if I'll do anything more with it, as it's obviously unfinished and crappy at the same time.

[Slothien483]

Can't quite understand how to install the program, any readme file available?  

[Ai]

This older thread:
http://www.wayofthepixel.net/pixelation/index.php?topic=1618.msg23719#msg23719

might further enlighten on the subject of C64.

Info about EGA64 and CPC (EGA64 was available on EGA adaptors with 256k of memory. It was only available in relatively-hi-res modes like 640x200 and 640x350)


Both of the above are based on RGB color cubes. No gamma correction has been applied.
To get accurate results on your display, gamma correction might help.

Topics that no one has covered here yet:
CGA (http://en.wikipedia.org/wiki/Color_Graphics_Adapter explains in -- too full! -- detail)
MSX-1 (the later MSX versions are probably too capable to suit this topic -- http://en.wikipedia.org/wiki/MSX)

[Helm]

Ai, CPC question: 4 colors from those single pixel in the whole pic, or 4 per 8x8 element or something?

And that Ega64 16 out of 64 colors could basically be used for stuff that almost looks vga if someone is smart enough. It's widepixels, 16 colors crammed into an 8x8 character should an artist want to, right? I might attempt something Ega64 just so I can fool people with it looking vga.

[Ai]

CPC doesn't have any per-cell limitations, the limits apply to the full screen in all standard cases. Nonstandard cases are that you can program raster effects to change about 2 of the palette colors per scanline if necessary, or switch between 'modes' (widepixel 16col/squarepixel 4col/tallpixel 2col) once per 4 scanlines (roughly). It's easier on the CPU to change the palette only once per 1/6th of screen (and I guess, also true for mode switching. Games don't mode switch rapidly anyway.).

http://en.wikipedia.org/wiki/Amstrad_CPC
has some exemplary screenshots in the 'notable games' section -- no games used the monochrome mode to my knowledge; the other two modes are demonstrated to good effect.
An example of CPC mode splitting is here

Re: EGA64
Haha, actually no -- EGA64 is somewhat-tall-pixeled(4:2.1875). The differences between it and VGA16 are: Slightly more resolution (640x400 VGA16 > 640x350 EGA64), and color choice (VGA16 64*** = 256k colors to choose your 16 from > EGA64 4*** = 64 colors to choose your 16 from.)

Re: weird limitations
You probably can't program an EGA64 adapter to do any weird modes (eg 160x200x(16 of 64) as you said Helm). I have not seen a pic of that kind here, nor have I seen a VGA-tweaked (ie modex) pic here. (eg designed for 320x480 mode -- you can find something very like that in Danny's gallery on gfxzone -- more than one, I think. I have drawn exactly one such pic myself.)
320x350x(16 of 64 or 262144) might be possible to tweak VGA16 to do. 0.91:1 aspect ratio. Or the 160x200x(16 of 64 or 262144) mode that EGA is too inflexible to cope with.

[Helm]

I mistakenly wrote 'widepixels' where I wanted to write 'singlepixels'. I wouldn't expect an EGA-type mode to do native widepixels, as they're not really made for that. Can you link to the Danny picture of that type you spoke of?

[Ai]

http://www.gfxzone.org/personal/danny/01/danny-winter_queen.html
Was the one I recalled, and it looks like he has no others.

(EDIT: For some reason, 320x480 is substantially harder than 160x200 to work with for me. It's probably in that middle zone between 'enough' and 'too much' definition for me and that causes the confusion.)

[Helm]

Hehe so cheesy. Nice interlace dithering here and there though. Of course a copy.

[ptoing]

I think that Danny pic some Amiga AGA hires mode. Not 100% sure tho.

[Helm]

That's what I thought also, since, Danny... PC... why? Lazur has a big amount of tallpixel pieces too.

[Ai]

Yeah well I did say 'like that' , not that it was done for/on the PC:)

[Ai]

I've just been reading up on gamma,
And I realize the colors I gave are wrong for modern sRGB displays, since CPC is a linear RGB colorspace and sRGB is a nonlinear (gamma 2.2) colorspace.

The revised colors:


Something to keep in mind for any future posters to this thread -- check your gamma. Because most retro palettes
were drawn on a device with linear RGB, you'll need to gamma-correct the color values.

EDIT: the above is bullshit, I retract it. Nonlinear gamma is normal, so it is only a matter of correcting from the original gamma to the modern sRGB gamma ~2.2 (which is a three step process, first apply gamma (1/original_gamma), then apply gamma (~2.2)
NOTE: sRGB gamma isn't actually 2.2 (pc) or 1.8 (mac), it's a splicing together of two functions, one of which is linear (from 0..12 AFAIK) and one of which is exponential (gamma 2.5, for PCs)), which is commonly approximated by gamma 2.2.

More on gamma later, in a new thread.

[gamingjustin]

A really nice page concerning c64 limitations: http://www.studiostyle.sk/dmagic/gallery/gfxmodes.htm
and some tools for c64: http://www.haddewig.de/nogames64/grafix.html