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5200 and A8 color differences


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I never did find a satisfying answer for color differences on the 5200 and A8 hardware. Why is it that some colors are sometimes more greenish ? I know I ran into this with my first game Koffi, where to get red fire , I chose a color that on emulators looks purplish. But on the real system, it was red.

 

To illustrate my current issue:

 

Here, I'm using Altirra and I prefer the Kingdom 1 yellow sand color (PAL colors) over the green hue shown by default (NTSC colors).

 

post-37-0-67896600-1485826501_thumb.png

 

I have noticed this before where sometimes (NTSC) 5200 AdvII looked a bit too green in Kingdom 1, both in some emulators and at a Philly Classic show I noticed it on the TV. But on my TV at home, it looked more yellow. This is true of real hardware but not all the time - see the video below of real 5200 Adventure II, with more yellowish sand color, the color/hue we intended and expected. It seems to vary, based on different videos and pictures I've seen.

I mainly use Atari800win 4.0 for playing A8 games and developing games. For Adventure II, I only use NTSC mode and the colors look better, more of the yellowish hue than the green, as shown in the next screenshot. Atari800win NTSC palette looks like Altirra's PAL palette. both can't be correct!

post-37-0-73008700-1485826521_thumb.png

I don't currently have a programmable cart to actually play AdvII XE on real hardware, so I don't know what color it'll appear on my 800XL or XE game system. (I gotta get a Classics eprom cart soon!)

So, is there any knowledge on this difference and which I can expect an 800XL, or Atari XE system, to look like? It's mostly the yellow vs green of kingdom1 I take issue with - the other kingdom's colors are usually consistent from what I've seen.

Here is a video of real 5200 hardware, taken with a camera. This is how we intended the Kingdom1 screens to look - with more yellowish sand, not too green.

 

https://www.youtube.com/watch?v=xWGn3K6dlBo

 

 

I'm not sure exactly which color (the yellow vs greenish hue) I'm talking about either. These screens use 00 (black) and also E6, C6, F6, or E4 though .

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Altirra's default colors have changed a couple of times over various releases. If you started on an older version of Altirra, you should try resetting the colors via the Preset button in the Colors dialog as you may have colors from an older version. In the recentl 2.90-test releases, I've retuned it again so that the default is a "modern TV" spec with a separate "contemporary" spec for colors that deviate from the NTSC spec but may better match TVs of the time (Commodore 1702) and descriptions of the colors. The default spec should be less green than what you have up there.

 

That having been said, keep in mind that:

  • No two machines have the exact same colors, due to the color adjustment. NTSC is more prone to this, as the color encoding on PAL machines has quirks that limit variation.
  • NTSC and PAL computers should not have the same palette. There are significant differences in the way that NTSC and PAL systems generate color and you can't even adjust them to get them to match. This is why recent versions of Altirra have split palettes.

(Update: I checked the palette, and the problem is that the colors involved are all at the end of the chain at hues 12, 14, and 15. The higher numbered hues have the most variation on NTSC, and in particular hue 15 may be anywhere from green to orange depending on how the computer is adjusted. On PAL, hue 1 and 15 are hardcoded to always be the same hue, no matter the adjustment.)

Edited by phaeron
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Wow there are significant changes between NTSC on Atari800 PLus 4.0 and Altirra 2.90 pre-24. So which one is correct? Or is the game programmed wrong because it was referenced to a machine that was out of adjustment?

 

ALTIRRA NTSC

post-4806-0-68513800-1485839660_thumb.pngpost-4806-0-41420400-1485839659_thumb.pngpost-4806-0-09903400-1485839660_thumb.png

 

ATARI WIN PLUS 4.0 NTSC

post-4806-0-40244300-1485839713_thumb.pngpost-4806-0-91498300-1485839711_thumb.pngpost-4806-0-71771600-1485839712_thumb.png

 

If you set Altirra to PAL, then it's so much better. On the other hand, the colors in Star Raiders on Atari Win Plus are not correct. The shields are too green, low energy at the bottom is near violet as is the warning when coming out of hyperspace into battle, and the galactic chart grid is too green.

 

Altirra Authentic NTSC is very close to getting Star Raiders correct.

 

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IIRC, Atari800WinPL does not change palette when switching from PAL to NTSC, instead you have to choose the palette manually. So you may be running that emulator in NTSC mode with PAL palette. You can change palette in Altirra manually to PAL colours if you prefer that setting.

Edited by pseudografx
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It doesn't change, that's right. I was just using the default palette. Whatever is internal to the emulator. It looks right.

 

Well, no matter, I suppose switching the palette in Altirra isn't that big a deal for one game. I'm just glad we have these emulators and choices. I certainly don't mean to complain about that!

Edited by Keatah
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a properly adjusted crt and computer always have the same color in ntsc.... that is why there were adjustment programs for that purpose and their were crt television as well as vga monitor ajustment rigs just for that purpose..... I have dealt with plenty of PAL televisions with no way to adjust them by the normal user the covers had to come off and be adjustment was done inside the set... sometimes in firmware... so adjust you television/crt/lcd with a an appropriate calibration device and then adjust the pot on the Atari as the color generator using the same device. I have found that and the color charts allowed for proper adjustment. In rare cases I had to align and adjust the gun drivers individually on the back of the card attached to the tube...most modern devices allow you to change the color temperature as well as tint these days.....

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