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Forums > CSDb Discussions > colodore is the new pepto
2016-12-12 00:26
pepto
Account closed

Registered: Nov 2004
Posts: 35		 colodore is the new pepto

Hey guys, I remeasured the video-signals of my VIC-II's and slightly updated my 15 year old attempt at calculating an rgb-clone. While at it, I also measured VIC & TED and made a little website about it, that allows you to adjust brightness, contrast and saturation as you like and then save your own custom palette to a png-file.

http://www.colodore.com


I took extra care to make sure, that the brightness, contrast and saturation sliders behave the same way as my 1084s.

While closely comparing my LCD to the 1084s, I found that making the transparency of scanlines dependent on YUV's Y (so they are less visible for brighter colors) looked a lot more like the real thing. I also noticed that the phase-shift on odd-lines happens for YUV's V only and there's even a name for it in video-lingua: hanover bars.

After implementing this, I'm happy to say that the images on my LCD and 1084s are remarkably close.


I will write a more detailed article about it in January, but seriously need a christmas-break first...

Cheers,
pepto
 
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2016-12-14 09:53
willymanilly

Registered: Jan 2016
Posts: 27		 Nice work Pepto! I've already peeked at your source code and have started using some of that logic in my emulator Z64k. I look forward to your article in the new year. Enjoy the Christmas break. :)
2016-12-14 11:53
pepto
Account closed

Registered: Nov 2004
Posts: 35		 Thank you... :)


OK, after getting some vibes via pm, that it might be upsetting for some guys that there isn't one ultimate "answer" to the urge to finally have one set of rgb-values to rely on, I decided to write down some thoughts - sorry for getting in tl:dr territory.

I do realize people like standards and a settled environment. I also get perfectionism (can you tell from the colodore-ui, that I like pairs of three and aligned things?), but even if this might make things more complicated in some situations, I think getting BACK the freedom to tweak things like on a real setup, is actually a relief - something I really missed when using emulators and such.

The perfectionist in me actually doesn't like "Hanover Bars" that much, they f*ck up yellow so that it looks greenish. The reason I included them (even by default) is, that they are a "display setting" and don't affect the palette colors at all. Yellow actually looks different depending if you are on even or odd lines and you can't depend on that either, because someone might scroll your graphics. Some TV sets even have built in hardware to further mix the color-portion of even and odd lines, in order to hide Hanover Bars. You may just deactivate them in the colodore-options, if you don't want them to be part of your display.

If there's one thing I can say obout my original C64 and C1084s, it's that graphics look GREAT on it - I really LOVE how it looks <3. I also never stop tweaking the color, brightness and contrast knobs, depending on how bright the surrounding daylight is. Everything about this feels right, this is like Commodore's engineers intended and how it has always worked and the reason I use the real machines to this day.

Do the Hanover Bars make yellow look greenish on it? Hell yeah they do, but why complain if there's so much else to like about its appearance? VIC chips output an analogue signal, that gets distorted in a gazillion kind of crazy ways.


Regarding palettes with different amount of saturation, I like to compare that to bass in music. I know people who tweak their audio-equalizers in such ways, that music is so bass-heavy that I can't enjoy it any longer - but they love the f*ck out of it. I also know peeps who want music to sound natural, linear and realistic - I sometimes think they should really dial more bass in. They surely can't agree on what the "standard way" of listening to music is.

I received a pretty large amount of mails throughout the years, from people who had something to complain about my exemplary calculation. It's "too dull", "too dark", "saturation is too low", etc. It's not that surprising, as people know the colors from when they were able to equalize them for themselves. What I suggested to most of them, is to follow the example and calculate with their own amount of saturation or add some brightness. It's after all just an example and I didn't think people would just take and run with it.


My goal is simple, I want C64 graphics to look as good when looking at them on a tablet-device, as they look on the real thing and I think this goal is more close with colodore, that's the one reason I'm sharing it. I'm not in it for fame or money... ;^D

I'm sorry if this introduces more variables into some specific workflows, especially for some of my favourite pixel-artists, but you can just keep using the "pepto palette" if you're happy with it. The reason I actually chose a name this time, is that I certainly don't want to make anything obsolete. What is different from the 15 year old research to colodore, is that I tweaked the purple/green angle slightly and phase-shifted all colors a tiny notch in the underlying logic as my new measurements suggest, that this is more accurate.

Also my luma-values have always been based on Marko Mäkelä's measurements (a fact I never hide), I just tried to reduce them to a common denominator - a somewhat quantized version that I feel represents the different chips I tested personally very well, even if every one of them looks slightly different.

I hope this clears up some confusion.
2016-12-14 15:23
chatGPZ

Registered: Dec 2001
Posts: 11114		 the bass/music analogy is a very good one, thanks for coming up with that - must remember.

VICE also phase shifts all colors a bit (4.5 degrees iirc) already :)
2016-12-14 18:00
jailbird

Registered: Dec 2001
Posts: 1576		 No offence towards Pepto, as the old palette seemed to me as the golden ratio and it is just fabulous, but this new thingie looks like someone got wild on the color settings of a TV set and set it to the highest value. Or maybe I am just going blind as I get older... Dunno. I get it that it is measured and technically more correct but for some reason it doesn't feel right to me...
2016-12-14 18:13
chatGPZ

Registered: Dec 2001
Posts: 11114		 i just hacked it into chameleon.... and what can i say? looking at the VGA and 1701 side by side, they look surprisingly similar now. although the yellow _IS_ SCREAMING YELLOW =D

edit: one thing i noticed - it looks a lot less SCREAMING when you actually configure the output how it should be, ie enable scanlines and everything else.
2016-12-14 19:06
pepto
Account closed

Registered: Nov 2004
Posts: 35		 Quote: No offence towards Pepto, as the old palette seemed to me as the golden ratio and it is just fabulous, but this new thingie looks like someone got wild on the color settings of a TV set and set it to the highest value. Or maybe I am just going blind as I get older... Dunno. I get it that it is measured and technically more correct but for some reason it doesn't feel right to me...

Have you tried setting the sliders to something more pepto-like? For example brightness 50, contrast 85, saturation 40 (these are no scientific numbers, I just quickly tried by hand to come up with a pepto-ish look)...

And to get even less scientific... Here's the real 1084s vs. colodore on iPad, photographed with a phone, which has a hard time as brightness of crt vs. lcd-backlight is pretty different for the lense and the original image is also interlaced...



Great image btw., also loved it on the bigscreen at Breakpoint... :)
2016-12-14 20:38
v3to

Registered: Feb 2005
Posts: 150		 I am quite pleased of the Colodore colour approach. It is not because of discussing which saturation is right, it is because the control bars lead to an result comparable to my 1084s. Dark blue stays dark blue even with extreme settings.

The PEPTO palette is a similar basis, but if I try to adjust saturation or brightness this tends to unwanted undertones.
2016-12-14 20:41
ilesj

Registered: Jun 2012
Posts: 27		 Awesome! Thanks for this - this here addresses many issues around (especially) C64 colors and picture reproduction. And what Groepaz said, the bass analogy is excellent. With these dials both the ‘bass-heads’ and ‘audiophiles’ can set up a palette that looks right.

I have been using the ‘“classic” pepto palette always when working on C64 graphics. Sure, it’s dim and muted, but it represents very well how the colors relate to each other. If colors of a picture looks balanced with ‘pepto’, it looks balanced with real HW. Some of the more saturated and bright palettes around have the colour relations off sometimes in wild proportions. That makes any well crafted picture look like a dog barf and at least my eyes bleed. This is a proper way to crank up brightness and saturation!

And whoever is seeking “one true palette” there’s also the catch that any two random displays won’t look the same. Colour reproduction between different displays just won’t be the same - that would call for colour profiles, calibration etc. So no, those default COLODORE colors may not be anywhere near a good match with 1084 on _your_ display, even though for pepto it is.

And by the way, I think not many laptop displays, for example, can reproduce the spot brightness of a small CRT display, no matter what’s the brightness and contrast setting. Only recently dynamic range has become a thing with HDR standards for UHD TVs.
2016-12-14 21:41
chatGPZ

Registered: Dec 2001
Posts: 11114		 Quote:
And by the way, I think not many laptop displays, for example, can reproduce the spot brightness of a small CRT display, no matter what’s the brightness and contrast setting. Only recently dynamic range has become a thing with HDR standards for UHD TVs.

color gamut is another thing - VGA can not reproduce all colors that a PAL-CRT can (and the other way around)
2016-12-14 22:34
Oswald

Registered: Apr 2002
Posts: 5017		 I was satisfied with the 'pepto' palette, but if this would make it into vice, in a user friendly way (realtime manipuation) that would be nice.
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