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Games that use Apple II-style artifacting for colors

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#76 _The Doctor__ OFFLINE  

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Posted Sun Mar 19, 2017 5:49 AM

The center picture I have never seen the like on a real Atari. The other two are the difference between my XL and XE. I remember, back in the day, not liking the reddish landscape, but I liked the fact that my XE had blue water at least. It wasn't until the mid 90's that I owned my first XL and was introduced to the green/purple artifacts, and absolutely hated it. The greens and purples always remind me of IBM CGA graphic colors which I also always hated. But I also used to fiddle with the tint on my TV/monitors to get artifact colors my eyes preferred. In any case, I prefer the artifact colors on games like Ulitma rather than my PAL S-video without them. Of course that's not true across the board, as I said before, only for games made to use artifacts. Amaurote definitely looks better without artifacting.

I simply replaced the Artifact capacitors on the xl to get the colors more correctly done.... so the fire place and clock in jingle disk were reddish and the tree greenish......

#77 Bryan OFFLINE  



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Posted Sun Mar 19, 2017 8:56 AM

It was explained to me that Altirra needs a little more work before it can do 90 degree shifted colors like the Apple II. And interestingly, only the Atari 800 can do it. All other models don't.




That's not exactly what was stated. First of all, Altirra doesn't need to do what the Apple II does. It needs to emulate the special-case artifacting of the 800 which isn't 90 degrees, but isn't quite 180 either. The only reason it's not emulated is phaeron wants better information on it.

#78 zzip OFFLINE  


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Posted Mon Mar 20, 2017 8:39 AM


It's just a screenshot of someone's Youtube video. I guess the colors themselves are going to be different depending on what machine you use. But my point was that NO Atari screen will look like that Apple screenshot, because the Apple is displaying more artifacted colors than are possible on an Atari, and also I think the Apple II's width in pixels is limited to something like 280 rather than the 320 that the Atari has.


exactly.  I think the apple II has the same number of bytes per line, but they use an extra bit to swap between two different artifact color sets for each byte,  which leaves them with 280 pixels, but up to 4 unique artifact colors  (red, blue, green, purple)  vs 320 and 2 artifact colors.  but that means that you while you can put red and blue in a single byte on apple, you can't mix say red and green.  It has to be either red + blue or green + purple.   I love how all the 8-bits have their own unique quirks with color placement :)

#79 zzip OFFLINE  


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Posted Mon Mar 20, 2017 8:51 AM

I get this from Applewin. Looks nice because of the green landscape and blue water.



Then from Altirra I get these, but not able to tweak it exactly like the Apple II.



With the Atari800 emulator, I got it to an acceptable green foliage/ purple water (passes for blue), kinda the reverse of your first screenshot

#80 zzip OFFLINE  


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Posted Mon Mar 20, 2017 8:59 AM

Really?!? I got news for you, ALL artifact colors are FALSE colors...there aren't any true colors. And yes, I see the quotes, on true, which only makes the statement more ridiculous to me. Regardless, who cares if dithering is used if it works?!?


But yes the program did use dithering patterns like checkerboard, etc., to make for example a fill of red and blue checkered dither to make a "purple" color, and in fact had an entire page or more of patterns to choose from, it also created more artifact colors like a yellow and light-green and pink (as solid looking on a composite screen as the basic red/blue or green/purple artifact colors) among others through choices of paint brushes with special pixel placement. In any case, I've been meaning to track down that art program again, if I find it I'll post it and you can see for yourself.


But to the Ultima stuff, sure, the Atari version doesn't use as many artifact colors as the Apple version. It doesn't mean it isn't possible. Weren't the C64 versions done in a high-res mode similar to Apple and Atari too? 


The C64 version of the Ultima games do not use artifacting,  C64 hi-res mode can place 2-unique colors in each 8x8 on screen block I think.   That limitation works out quite well for a tile-based game like ultima, and the C64 version is the most colorful of the 8-bits computer versions I think.

Edited by zzip, Mon Mar 20, 2017 9:00 AM.

#81 _The Doctor__ OFFLINE  

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Posted Mon Mar 20, 2017 11:28 AM

Some version of Ultima will as a fresh install ask what colors you see... it will then reverse the Artifacts based on what you select...  I remembered this, be very impressed... :)


There might be a mention of how to change it again later somewhere... but that I don't remember... anyways... artifact order was software select-able and a capacitor hardware mod took care of it and the color to a degree as well!

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