Those Decathlon screens show what I consider to be "imperfect" color. By this I mean the vertical lines present in the solid colors. It reminds me of the video issue of the top-loading NES. I don't know whether this is due to poor video circuitry in the CGA or perhaps that is the inevitable result of the artifact technique.
It's a result of artifact colors. If you zoom in on Servo's screenshots (especially Troll's Tale), you'll see those lines as well, especially in gray and green areas. I can make the Gaussian filter harsher to hide it, but that will make the text blurrier as well.
Of course, what is missing are the HORIZONTAL lines. As you pointed out before, the CGA creates a progressive signal. While this makes no difference on modern TVs that have line doublers and stuff like that, on a classic TV you will get a scanline effect, similiar to the NES, because only half of the lines are ever filled.
This is KQ with a simple 80s-style 2-line comb filter, wide-angle demodulation and 50% scanlines. I really like this TVy look. 😀
I had a thought while playing with my TV-Out on my GeForce 7800GTX cards today. Is it possible to use the TV-Out capabilities of a modern PC graphics card to "recreate" composite color video modes on a real color composite monitor? Doubtless this would require some tweaking, but if Powerstrip can let users tweak till their heart's content, why not this? It would eliminate the speed issues and provide for the most authentic experience available.
I actually mentioned the same thing somewhere, as I was playing with TV Out on my Radeon 9800 Pro a week or so ago... Will an NTSC TV work in place of a composite monitor?
There is little, if any difference between an NTSC TV with a composite video input and a NTSC composite monitor with a composite video input. Otherwise you would need an RF Adapter.
I tried to use a few games to show the composite video mode with the TV out, but it didn't really work.
Tried with what? DOSBox? An old PC with a CGA card?
I tried a few games with MESS and the Geforce 7800GTX, but it didn't work well. I saw artifacts, but nothing that looks quite right.
In other news, I bought an Apple IIe Color Composite Monitor and it should arrive on Wednesday. They are very highly regarded as composite monitors go (and have a monochrome/color switch.) Unfortunately, the only artifacting color-based system I have is an Apple IIe Platinum, no PCs or PCjrs.
ok, here's the shots I got of Microsoft Decathlon:
I think the source of much confusion on my part earlier is that the Tandy seems to be causing more trouble than just the font; the colors are slightly different too. it's not noticable in all of the colors, the ones that stand out the most are brown/green and yellow; On the 5150 the yellow is slightly more goldenish, and whatever color it's supposed to be appears brown. On the Tandy the yellow has a very slight greenish tint, and the whatever color it's supposed to be appears more green than brown. I also included some KQ1 shots. I tried the test program on the 5150; with the IBM CGA no changes were visible on the similar screens, as expected. I couldn't try out the clone though; for some reason none of my dos disks are working with the clone installed, but work fine with the IBM installed!? Bootable games work fine with the clone though...hmmm....
And here I thought the output of a video card wouldn't change depending on the machine it's installed in... 😕
In all of the attached shots I used the same capture card settings and didn't make any adjustments.
I don't understand how there could be differences, other than the font, between the IBM PC 5150 and the Tandy 1000, considering they use the same exact IBM CGA graphics card, copy of King's Quest and composite video monitor/TV. Also, the Tandy screenshot shows a slightly better picture than the IBM screenshot. The computer's BIOS cannot dictate what colors the IBM CGA displays. Perhaps the electrical enviornment inside the Tandy is more friendly to the analog composite color generation of the CGA than the 5150.
It would be interesting to see what King's Quest would look like using the Tandy composite video output, but according to MESS, the IBM version does not work correctly and the Tandy version uses a 320x200x16 mode, which will display in monochrome on a color composite monitor.
Thank you for posting these screenshots.
So the ugly variant is the way to go for Decathlon? Too bad. I think I'm still going to offer the second, cleaner-looking version as an option. That's five options now:
- color decoder: standard NTSC/US fleshtone improvement/Japanese fleshtone improvement
- comb filter: none/2-line (more to come?)
- scanlines: 0-75%
- equal brightness among colors 1-6 (improves Decathlon)
- vertical line remover (Great Hierophant's "imperfect color")
I wonder if this confuses the average user...
As for the hue differences between the Tandy and the 5150, they seem negligible to me. Tandy is about 7 degrees to the right of 5150. Were the Ms. Pac-Man shots taken on the 5150 or on the Tandy?
By the way, did you increase the brightness a little on your Ultima II shots? They look a little darker here...
wrote:I don't understand how there could be differences, other than the font, between the IBM PC 5150 and the Tandy 1000, considering they use the same exact IBM CGA graphics card, copy of King's Quest and composite video monitor/TV.
I don't understand it either, but it's there; it's not a huge difference and isn't as noticable in some colors as others. The difference seems easier to spot on my tv than the captured screenshots.
Also, the Tandy screenshot shows a slightly better picture than the IBM screenshot.
There isn't really a noticable difference on either of my tv's. On the capture card the IBM appears very slightly noiser, I might have just grabbed a noisier frame.
It would be interesting to see what King's Quest would look like using the Tandy composite video output, but according to MESS, the IBM version does not work correctly and the Tandy version uses a 320x200x16 mode, which will display in monochrome on a color composite monitor.
I think that's just a problem with the emulation; I think I tried the PC version of King's Quest on the Tandy with the Tandy video and it worked ok. However the colors from Tandy's composite output are very different than either of the CGA's I have. I haven't tried the Tandy version of KQ, but I don't remember any games with 320x200x16 mode displaying in monochrome on composite displays.
As for the hue differences between the Tandy and the 5150, they seem negligible to me. Tandy is about 7 degrees to the right of 5150. Were the Ms. Pac-Man shots taken on the 5150 or on the Tandy?
Ms. Pac-Man I did on the Tandy. The difference is definitely subtle; where it stands out most (to me) is the brown color; on the Tandy it looks a little too green. Any idea how there can be a difference at all, even a subtle one?
By the way, did you increase the brightness a little on your Ultima II shots? They look a little darker here...
I have the brightness increased in all of my shots actually; the default capture settings are way too dark. I think I did up Ultima II a little more than normal...
I wonder if this confuses the average user...
I'd have to say yes! Confuses me from time to time at least...
wrote:I don't remember any games with 320x200x16 mode displaying in monochrome on composite displays.
Well, as shown in the source code bit posted before, Sierra explicitly turns on the color burst bit in 320x200x16 mode, so they of course appear in color. The programmer's comments say it's a BIOS bug that the color burst is (supposedly) off by default; if it's indeed a BIOS bug and not by design, maybe you have a later BIOS version which has that bug fixed.
wrote:Any idea how there can be a difference at all, even a subtle one?
The original IBM CGA derives the color burst reference signal from the 14.318 MHz clock signal on the system bus. It's likely that the 4.77 MHz bus clock signal is slightly delayed from the master 14.318 MHz clock signal (because it has to go through a clock divider first), and that this delay varies from mainboard type to mainboard type, depending on how much extra "distance" the clock-divided signal has to overcome. 😀
I would imagine that those clone cards that have their own clock signal generator are not affected by this problem.
wrote:I think I did up Ultima II a little more than normal...
Good. I was afraid my algorithm was off or something.
wrote:Confuses me from time to time at least...
Well, these are all picture improvement options.
- A non-standard "Color Decoder" makes colors look "nicer" to the untrained eye.
- "Comb filter" reduces color bleeding. It's obvious to me that your capture card uses a 2-line comb filter. Compare the following two Ultima III shots (hue = -15) with and without comb filter; look at the mountains.
The others options should be self-explanatory.
By the way: I know that by now I must be getting on your nerves, but what kind of CGA RGBI monitor do you have? Is it the original IBM 5153 Color Display? I'm asking because I'm still not certain if color 6 is supposed to be "brown" or "dark yellow". Everyone seems to agree that it's brown, but I have my reasons to believe it should be dark yellow. Is KQ1 in "RGB" mode yellow or brown?
wrote:Is it the original IBM 5153 Color Display? I'm asking because I'm still not certain if color 6 is supposed to be "brown" or "dark yellow". Everyone seems to agree that it's brown, but I have my reasons to believe it should be dark yellow. Is KQ1 in "RGB" mode yellow or brown?
No, I don't have a 5153 color display. I have three RGBi displays, one's the PCjr display (and works only with that system), the other two are Tandy CM-5's (despite the same model number though they both look quite different with different size/shape casing, etc.). On all of these color 6 appears as brown.
No, I don't have a 5153 color display. I have three RGBi displays, one's the PCjr display (and works only with that system),
I think then we can safely say that the true color is brown. The 5153 and the 4863 very probably use the same exact same CRT circuitry. They look different, the 4863 has a speaker built-in for the PCjr. sound and has a different style cable, but that should be the only differences between the two monitors.
Interestingly, the 4863 can almost definitely work with the IBM 5140 Convertible /w a CRT display adapter addon because they use the same pinout and connector.
That's five options now: - color decoder: standard NTSC/US fleshtone improvement/Japanese fleshtone improvement - comb filter: n […]
That's five options now:
- color decoder: standard NTSC/US fleshtone improvement/Japanese fleshtone improvement
- comb filter: none/2-line (more to come?)
- scanlines: 0-75%
- equal brightness among colors 1-6 (improves Decathlon)
- vertical line remover (Great Hierophant's "imperfect color")
I wonder if this confuses the average user...
It may confuse those not initiated into the subleties of NTSC composite color or the CGA color capabilities. Would it be possible to add a seventh option, RF/composite signal to show how bad the unfortunate had it back in the day? I know the CGA had a header for an RF unit. What about an eighth, color/monochrome?
wrote:On all of these color 6 appears as brown.
Damn...
wrote:Would it be possible to add a seventh option, RF/composite signal to show how bad the unfortunate had it back in the day?
Very funny. How does an RF-modulated signal look like anyway? I never used one of these.
wrote:wrote:wrote:Incidentally, running the game without the switch will cause a crush sooner or later
I wasn't aware of such power.
Well, it says so on spacequest.net and I also witnessed it myself - if I started the game without the -N switch, sooner or later it asked for a missing 992.V56 or 993.V56 file. It's surprising that you're not aware of this, since you know SQ4 so well.
I think he was making a joke about your typo ('crush' instead of 'crash').
JAL
wrote:wrote:On all of these color 6 appears as brown.
Damn...
Isn't the distinction between brown and dark yellow a bit subjective? I always considered color 6 to be dark yellow on the CGA, and brown on the EGA (it was darker on EGA than on my clone CGA).
JAL
"Dark yellow" is R=0.66 G=0.66 B=0.00; "Brown" is R=0.66 G=0.33 B=0.00; objectively. In RGBI, color 6 has bits 1 and 2 set, meaning that R and G should be equally bright, resulting in dark yellow; "brown" is not possible at all if you follow the RGBI color model strictly. If apparently all known RGBI monitors display color 6 at brown, they must have special circuity to recognize color 6 and lower the green signal accordingly. On a composite monitor, color 6 is always dark yellow. My old Tseng ET4000 had port-perfect CGA emulation; in EGA/VGA mode, color 6 of course was brown, but in CGA mode, it was dark yellow. But if Servo says it's brown on his CGA RGBI monitor, I guess I'll just have to accept that (even though I think yellow would look a lot better in 4-color RGB games).
I will never understand why IBM used Red, Green and Brown for Palette 0 instead of Red, Green and Blue or Red, Green and White. Similarly, the Palette 1 colors would be better as Cyan, Magenta and Yellow or Cyan, Magenta and Black. These, along with the right choice of background color, properly reflect the RGB and CMY color models. If I find someone who has a 5153, I will ask them what the color looks like, but I would almost guarantee that the color will be brown.
As usual I tried some pictures; here's KQ on the Tandy CM-5. And as usual the color doesn't turn out terribly great with a digital camera. I had an opportunity to buy a 5153 display rather cheap, but I already have so many displays I couldn't figure out where I could possibly put the thing so I passed on it. I also can't figure out who thought Cyan, Magenta, and White was a good combination.
