Re: [Atari800-users] colors
Brought to you by:
joy
Menu
▾
▴
Re: [Atari800-users] colors
|
From: Tomasz K. <tom...@in...> - 2020-11-19 02:27:28
|
I'm sorry I'm a bit late to reply, but since I am the person responsible for Atari800 colours, I guess I might provide some input here. 1. Every Atari computer unit produces somewhat different colours. The video generation process is analogue in nature. Obtained colours depend on adjustment of the colour pot at the bottom of the computer, on the adjustments of the TV, and even on the temperature of the chips inside the computer. That's why there are many different palette files available. 2. Palette files were a useful tool to obtain colours the user wanted back when we didn't know better (especially as every user wanted slightly different colours due to point 1.), but now we have both NTSC and PAL GTIA colour generation reverse-engineered, so palettes should be considered obsolete. 3. Atari800MacX is, judging from your screenshot, still being based on incorrect colour model from the old Atari800. It still uses the old "black level/white level" nomenclature, as you noticed. Without using palette files, it will be impossible to match its output in Atari800. 4. Though if you use the same palette file in Atari800 and Atari800MacX, and disable "Also adjust external palette" in Atari800 and "Adjust File Palette" in Atari800MacX, the display will be 100% identical in both emulators. But it's best to avoid palette files in Atari800 altogether, because... 5. The Display Settings menu of Atari800 contain several parameters to adjust the display - brightness, contrast, saturation, tint, gamma, and GTIA delay (the last one represents the colour pot in the Atari computer). They replicate the functionality of the TV adjustments and more, and they are meant to allow replicating of every possible colours produced by real Atari computers, thus eliminating the need for palette files. We provide reasonable default settings though - it's probably best to just use the defaults, by selecting the "Color preset -> Standard" setting. 6. All those settings mentioned in p. 5 are stored separately for NTSC and PAL though. If you switch the video system in Atari800, you can adjust the setting for that video system independently. 7. NTSC and PAL GTIAs generate colours differently. The end result is, colours on PAL and NTSC are significantly different (you shall notice it when you switch System Settings -> Video system). The main difference is, the phase shift is different in PAL. Hue #1 is greenish-yellow on NTSC, but golden on PAL; other 14 hues are also shifted. That is why you see the discrepancy between Atari800 and Atarii800MacX: the Real.act palette was created from output of a PAL Atari computer, while you are running Atari800 with the video system set to NTSC. 8. You know the reputation of "Never The Same Color". The issue with the default NTSC colour preset in Atari800 is, it represents only the output of more modern TV sets. If you connect an Atari to a modern LCD TV, you get a palette matching the default Atari800 preset. (Except the possible difference of brightness, contrast etc.). Same if you output to a CRT monitor with correctly-calibrated colours, like the ones they used in TV studios. But for some reason, many CRT TV sets sold to the public during Atari's heyday (and later, too) displayed significantly different colours - in particular hue #1 was more golden. That display can be easily reproduced in Atari800 by setting Tint (while having video system set to NTSC) to ca. 0.14-0.18. Coincidentally, the resulting NTSC colours become then remarkably similar to PAL ones. (This might explains why PAL GTIA colours are what they are - when designing PAL GTIA, they probably chose the colours to match what they have seen on NTSC, not knowing that their CRT monitors were not exactly cailbrated.) 9. The issue described in p. 8 was already a problem in the early 1980s. Different NTSC software was written with different assumptions with regards to colours. Let's look at "Pole Position" and "Rescue on Fractalus!" for instance. For both titles we have contemporary reference footage - for "Pole Position" there is that scene in "D.A.R.Y.L.", and for "Rescue on Fractalus!" there is the 1984 Lucasfilm press conference video. The "Pole Position" cartridge dynamically adjusts its colour palette depending on the TV system the Atari computer uses, specifically to address the NTSC/PAL differences. It was clearly written under the assumption that NTSC hue #1 is greenish-yellow. When run under Atari800 with the Default preset, the sky is blue, grass is green, and curbs are red-white. If tint is adjusted to 0.14 or beyond, all colours are way off. "Rescue on Fractalus!" though was written with the assumption that hue #1 is golden. The mountains, which use hue #1, are supposed to be brown, not greenish as displayed on the default hue setting. The sky is also too much on the green side. If instead tint is adjusted to 0.14 (and saturation is overriden way up to 1.0), the mountains, the sky and other colours match the 1984 footage much more closely (though not ideally - an old VCR tape introduces its own colour issues). So, to sum it up - just adjust NTSC tint to 0.14 or a bit more, and Atari800 should match your real TV's output much closer. Have in mind though, that some software will then look worse. Could you run "Pole Position" on your real TV and tell us what colours you see? Best regards -- Tomek On 16.10.2020 at 00:46, Kay Savetz wrote: > Thanks. I'll try this. > > -K > > On Thu, Oct 15, 2020 at 6:42 AM Cliff Hatch via Atari800-users > <ata...@li... > <mailto:ata...@li...>> wrote: > > I don't have any experience of Atari800MacX, but I get good colour > reproduction with Atari800 on Linux using the default video settings: > > COLOURS_NTSC_SATURATION=0 > COLOURS_NTSC_CONTRAST=0 > COLOURS_NTSC_BRIGHTNESS=0 > COLOURS_NTSC_GAMMA=2.35 > COLOURS_NTSC_HUE=0 > COLOURS_NTSC_GTIA_DELAY=26.8 > COLOURS_NTSC_EXTERNAL_PALETTE= > COLOURS_NTSC_EXTERNAL_PALETTE_LOADED=0 > COLOURS_NTSC_ADJUST_EXTERNAL_PALETTE=0 > > I tried changing to your saturation, contrast, brightness and > gamma settings. This had a small effect only - the display still > looked good. > > However, loading the Real.act palette gave me very distorted > colours, similar to those you have seen. > > I don't know the history of the external palettes. The only one > that gives me reasonable results is XFormer.act, but even it is > not great - a little too bright. Strangely, the one called > default.act produces similar distortion to Real.act (so I guess > there must be a default internal palette that is different to the > external one). > > The best settings I can find are the above defaults, with no > external palette loaded. > > Best Regards > > Cliff > > On 14/10/2020 16:33, Kay Savetz wrote: >> Because the way the settings work on the two systems are >> completely different. I don't know how to make them the same. >> >> I've figured out that I can set COLOURS_NTSC_EXTERNAL_PALETTE to >> Real.act, which is a start. But the colors still don't match, and >> the terminology between the linux config file and the Mac >> preferences is different enough that I don't know what to change. >> (e.g. Saturation, Contrast vs. Black Level, Intensity.) >> >> On linux: >> >> COLOURS_NTSC_SATURATION=0.26 >> COLOURS_NTSC_CONTRAST=0.72 >> COLOURS_NTSC_BRIGHTNESS=-0.16 >> COLOURS_NTSC_GAMMA=2 >> COLOURS_NTSC_HUE=0 >> COLOURS_NTSC_GTIA_DELAY=26.8 >> COLOURS_NTSC_EXTERNAL_PALETTE=Real.act >> COLOURS_NTSC_EXTERNAL_PALETTE_LOADED=1 >> COLOURS_NTSC_ADJUST_EXTERNAL_PALETTE=1 >> >> On Mac: >> >> Screenshot 2020-10-14 at 8.07.19 AM.jpg >> >> >> >> >> On Wed, Oct 14, 2020 at 12:09 AM Miro Kropáček >> <mir...@gm... <mailto:mir...@gm...>> wrote: >> >> Are you sure you are using the same palette and/or NTSC/PAL >> settings? >> >> On Wed, 14 Oct 2020 at 06:12, Kay Savetz <ke...@sa... >> <mailto:ke...@sa...>> wrote: >> >> Hi Atari800 people, >> >> Today I made a little program on Atari800MacX, then >> copied it to @Atari8bitBot on Twitter, which uses >> atari800 on linux. I noticed that the colors are very >> different. Frankly, I like the Mac colors better (and I >> think they are more accurate to my real Atari.) >> >> Atari800MacX has many color palette options. I use >> Real.act, which I think is the default. >> >> Can someone suggest settings for the Linux atari800.cfg >> to make the colors better? >> >> Thanks >> Kay >> >> Screenshot 2020-10-13 at 8.59.22 PM.jpg >> >> >> _______________________________________________ >> Atari800-users mailing list >> Ata...@li... >> <mailto:Ata...@li...> >> https://lists.sourceforge.net/lists/listinfo/atari800-users >> <https://lists.sourceforge.net/lists/listinfo/atari800-users> >> >> >> >> -- >> http://mikro.atari.org <http://mikro.atari.org> >> >> >> _______________________________________________ >> Atari800-users mailing list >> Ata...@li... >> <mailto:Ata...@li...> >> https://lists.sourceforge.net/lists/listinfo/atari800-users >> <https://lists.sourceforge.net/lists/listinfo/atari800-users> >> >> >> >> _______________________________________________ >> Atari800-users mailing list >> Ata...@li... <mailto:Ata...@li...> >> https://lists.sourceforge.net/lists/listinfo/atari800-users <https://lists.sourceforge.net/lists/listinfo/atari800-users> > > > _______________________________________________ > Atari800-users mailing list > Ata...@li... > <mailto:Ata...@li...> > https://lists.sourceforge.net/lists/listinfo/atari800-users > <https://lists.sourceforge.net/lists/listinfo/atari800-users> > > > > > _______________________________________________ > Atari800-users mailing list > Ata...@li... > https://lists.sourceforge.net/lists/listinfo/atari800-users |
