Displaying the Colour Red on A8s

[YSG2020]

Perhaps this has been answered before, but why do my XLs and XEs do such a poor job of creating the colour red on the screen. At best it is a dark pink.  I have a UAV running through a high quality converter displaying on a really nice SVGA CRT monitor.  Still the same dull pink as on RF Out on a TV. All the other colours seem vibrant and good on all my machines, but the reds suck. What’s the reason for this? Is there a problem or shortcoming with the GTIA or something else?  Could this be an age issue or bad caps effecting this particular colourband freq like the red-shift issue on old photographs? I don’t remember the reds looking so dull 30 years ago. 

Edited April 5, 2020 by YSG2020

[_The Doctor__]

NTSC, adjusted... never noticed it...……….. are you PAL or something... many discussions about this on PAL some fixes and adjusts, color palette choices etc.

[R0ger]

What do you mean red ? There is no such thing.

[Rybags]

Colour 3 is red on NTSC and PAL.  Supposedly red also occupies 4 on NTSC but not on PAL (it's more towards violet)

 

The problem of "pink" is due to lack of saturation.  A8 colours are oversaturated in the 0-2 luma range, about right for 4-8 and undersaturated above that.

 

Good idea for a mod there - saturation corrector though do the likes of Sophia allow modifying the palette?

[Faicuai]

2 hours ago, YSG2020 said:

Perhaps this has been answered before, but why do my XLs and XEs do such a poor job of creating the colour red on the screen. At best it is a dark pink.  I have a UAV running through a high quality converter displaying on a really nice SVGA CRT monitor.  Still the same dull pink as on RF Out on a TV. All the other colours seem vibrant and good on all my machines, but the reds suck. What’s the reason for this? Is there a problem or shortcoming with the GTIA or something else?  Could this be an age issue or bad caps effecting this particular colourband freq like the red-shift issue on old photographs? I don’t remember the reds looking so dull 30 years ago. 

Reds cone out decent, even from a stock 800 NTSC:

 

 

 

 

It all depends, of course, WHERE do you source them from (on the color map). 

 

More samples attached.

[YSG2020]

OK.. WTF is wrong with all my XL's and XE's and/or my monitors AND TV's?  I knew I wasn't imagining things and they could/did produce red just fine back in the day.  Those red examples above you posted look just fine.  I will take a photo of my screen... All my reds are displaying as dull pinks and/or browns.  No adjustments on my monitors and/or TV's correct this regardless of the output I am using (UAV, composite, or RF on a monitor or TV).  This is very odd. All my computers are NTSC.

Edited April 6, 2020 by YSG2020

[_The Doctor__]

if it's all, are you using the same power supply to feed each? are you using the same cable or cord? what tv's are you using?   If you are sure your television is calibrated using the composite or s video in (some tv/monitors allow individual presets) make sure all are properly adjusted calibrated for a few other video sources as being correct....

then move on to the Atari... make sure the power supplies are putting out close to 4.9 to 5.1 volts under load...

then adjust the Atari color pot using the test patterns riddled through out the threads...

do this for each Atari and label each power supply as a set... Atari A power brick A          Atari B power brick B    etc...

Then if it is ever so slightly off you can make slight adjust on monitor/processor controls...

 

[YSG2020]

8 minutes ago, _The Doctor__ said:

if it's all, are you using the same power supply to feed each? are you using the same cable or cord? what tv's are you using?   If you are sure your television is calibrated using the composite or s video in (some tv/monitors allow individual presets) make sure all are properly adjusted calibrated for a few other video sources as being correct....

then move on to the Atari... make sure the power supplies are putting out close to 4.9 to 5.1 volts under load...

then adjust the Atari color pot using the test patterns riddled through out the threads...

do this for each Atari and label each power supply as a set... Atari A power brick A          Atari B power brick B    etc...

Then if it is ever so slightly off you can make slight adjust on monitor/processor controls...

 

Ah ha.... Yes, I am using one new power brick from BEST Electronics swapped between all my computers. Never tested it's output but it seems to work ok with them.  That makes complete sense.. It might be under-driving them I wonder?  I will test it! Thx!

Edited April 6, 2020 by YSG2020

[+Stephen]

Well, we have one decent saturated red, and a good 100 blues

[Faicuai]

1 hour ago, YSG2020 said:

OK.. WTF is wrong with all my XL's and XE's and/or my monitors AND TV's?  I knew I wasn't imagining things and they could/did produce red just fine back in the day.  Those red examples above you posted look just fine.  I will take a photo of my screen... All my reds are displaying as dull pinks and/or browns.  No adjustments on my monitors and/or TV's correct this regardless of the output I am using (UAV, composite, or RF on a monitor or TV).  This is very odd. All my computers are NTSC.

There's bit more than the eyes can meet on this topic, though.

 

As I mentioned, it all depends on WHERE (in Atari's HUE rows) you source red-colors from. That is key. Here are a couple of other examples that appear well rendered across PAL and NTSC standards (assuming your calibration is perceptually accurate):

 

 

 

 

 

However, load Zaxxon or Caverns of Mars, and then you start seeing really, really weird "reds" which I am now not sure if they were ever reds, to being with.

 

As for your end, you can try the following simple steps (in order to test color rendition with National Flags, which is the best starting point to confirm if your Atari fleet + video-path is rendering color closely enough (or far off):

 

1. Warm up machines for THREE (3) hours.

2. Launch ACP or COLORMAP (from Atirra additions).

3. Retard (negative-dial) HUE or PHASE on your CRT/LCD-TV or video-processor, until Hue $10 is GOLD (not parrot green-yellow, or chicken-yellow).

4. Adjust Atari POT so HUE $0A becomes a grayish-darkish BLUE (with only a minor hint of green on it).

 

Then launch National Flags and check:

 

1. USA.

2. Spain.

3. Venezuela.

4. Mauritius.

5. Zambia.

6. Sweden.

7. Tuvalu

8. Kenya.

 

The following will have perceptual errors due to use of $E0 and $F0 hues:

 

1. IRELAND

2. NIGER

3. SRI LANKA

4. NAURU

5. NEW ZEALAND.

 

Fortunately, the titles that use that band are much more limited than the ones that use $10 hue-band, plus we get 256 color GUARANTEED with the above procedures.

 

Go ahead and try it.

 

 

 

[+Cafeman]

I found that NTSC value $34 was the most like red and not too dark. Brighter hues look more pink. The at $40+ values you start seeing magenta and purples. Didn't some of us just talk about this same subject recently. 

[Faicuai]

4 minutes ago, Cafeman said:

I found that NTSC value $34 was the most like red and not too dark. Brighter hues look more pink. The at $40+ values you start seeing magenta and purples. Didn't some of us just talk about this same subject recently. 

Sure, but if the OP can't get $30 hue-band rendered accurately, we will never get reds right (for the most part).

 

It seems that is his main concern. 

[leech]

14 hours ago, Faicuai said:

Reds cone out decent, even from a stock 800 NTSC:

 

 

 

It all depends, of course, WHERE do you source them from (on the color map). 

 

 

So on the right side, (not sure about the left) there is that black line that goes down the middle.  On the other program that is similar to that (Atari Control Picture) I've noticed on all my Ataris except the 800xl it has that line there.  The 800XL doesn't have the line there and actually looks the nicest out of them.  Though I also noticed with that same program that it does a vertical overscan, so on the Dell 2007FP that I am using, the resolution bit gets cut off at the bottom.

[+Nezgar]

1 hour ago, leech said:

So on the right side, (not sure about the left) there is that black line that goes down the middle. 

That is a common issue due to the simple binary resistor ladder network transitioning all 4 GTIA luminance bits from 0111 to 1000. It is one of the things that the UAV corrects exceptionally well.

[Gunstar]

I get great reds on my currently stock 800 and incredible reds from my 1200XL with SV 2.1 video upgrade using it's chroma circuit. My 800 is NTSC and my 1200XL is PAL (converted by me). I don't get the black line down the middle of the color-table on either.

[leech]

1 hour ago, Gunstar said:

I get great reds on my currently stock 800 and incredible reds from my 1200XL with SV 2.1 video upgrade using it's chroma circuit. My 800 is NTSC and my 1200XL is PAL (converted by me). I don't get the black line down the middle of the color-table on either.

My 1200xl after the Supervideo 2.1 mod.

It definitely looks cleaner than it did.  First is Luma/Chroma, second is composite.  It still has that weird line in the middle.  At least for some reason with this computer vs one of my other ones, the NTSC signal on the CRT isn't messing up my camera as much!  But I definitely have good reds on both of those

Edited April 6, 2020 by leech

[Faicuai]

1 hour ago, leech said:

My 1200xl after the Supervideo 2.1 mod.

It definitely looks cleaner than it did.  First is Luma/Chroma, second is composite.  It still has that weird line in the middle.  At least for some reason with this computer vs one of my other ones, the NTSC signal on the CRT isn't messing up my camera as much!  But I definitely have good reds on both of those

 

Those color tables will bring out Start Raider's shields greenish (due to visible shift in $A0)... but it turns out that they are not green, they are a darker hue of blue-grayish (per its author and original rendering)

 

Also, hue band $F0 is overshot, while $E0 looking already close to $10 itself, which means $F0 is ahead of its place. Seems like the hue-ramp is compressed.

 

Color band $30 seems relatively well centered, still, which should definitely give you good reds.

 

Edited April 6, 2020 by Faicuai

[Gunstar]

1 hour ago, leech said:

My 1200xl after the Supervideo 2.1 mod.

It definitely looks cleaner than it did.  First is Luma/Chroma, second is composite.  It still has that weird line in the middle.  At least for some reason with this computer vs one of my other ones, the NTSC signal on the CRT isn't messing up my camera as much!  But I definitely have good reds on both of those

The best part about the SV 2.1 chroma on 1200XL is how much more vibrant colors are with GTIA modes like APAC with only every other line being color.

[leech]

50 minutes ago, Gunstar said:

The best part about the SV 2.1 chroma on 1200XL is how much more vibrant colors are with GTIA modes like APAC with only every other line being color.

It definitely looks good for sure!  Wish I could find the 'perfect' monitor for the A8.  the 1084S is pretty close.  Though I still have to flip the composite / luma connection then push a button for the switch.  I have an old CRT that we used to always use with the A8 back in the day, but I'm pretty sure it just has one RCA for audio and one for video.  Pretty sure it still works... I should see how the colors look on that ha.  I'm having more fun just playing with display output than I should...

[leech]

Cool, correct (?) Colors on Star Raiders on the old monitor I used 30+ years ago.

[Faicuai]

20 minutes ago, leech said:

Cool, correct (?) Colors on Star Raiders on the old monitor I used 30+ years ago.

Here, by Doug Neubauer himself:

 

https://dougneubauer.com/starraiders/

 

Here, certainly close to how I remember seeing them 37 years ago:

 

 

To the naked eyes, the yellow E:(energy) reading is less greenish and a bit more reddish. However, shields are pretty close enough to the original rendering intent.

 

 

[leech]

That is about the colors I am getting on the old CRT, but the phone camera picks up too much glare for me to be able to take a decent picture of the text.

 

Ultima IV still was purple, instead of blue.  ?

I did see on Atari Mania they have two versions of that game listed.

 

I also seem to have two cart versions of Star Raiders, one is labeled with the serial number, one says it is a 16k cart, but they both look the same visually.  I still need to do tests with FSII.