Amazing Dithering in CGA and EGA Graphics (and how it works)
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- Опубліковано 6 вер 2024
- We look at how dithering helps DOS games and some really great resources for doing dithering yourself.
Credits:
Famicat:
/ 742141992239550464
Michael Noland's Blog:
michaelnoland.c...
16 Colour CGA Dithering on Reddit:
/ newbiecclakeside_view_...
CGA Jam:
itch.io/jam/cg...
The Dithertron:
8bitworkshop.c...
Almost Public Domain Images: unsplash.com/
Images:
Boy in Woods: Annie Spratt
Teapot: Eduardo Froza
Cabin: Olivier Guillard
Retro PCs: Lorenzo Herrera
Cat: Cedric VT
Dithering in CGA using GIMP:
www.alexsolab.c...
Download GIMP:
www.gimp.org/d...
It's funny that I stumbled upon this video today because last week I found that dither tool and messed around with it. It's really cool. Also, your mom's hat is awesome!
Your GIMP workflow is bound to produce weird results because you change the palette colors after the actual reduction/dithering process. Don't let the indexed-mode conversion "generate optimum palette", but "use custom palette" with the destination colors. Just tried it with custom-defined CGA "ski fashion" and "bodily fluids" palettes, and the result is much better.
Yes, I think this is what I ended up doing a few years back when I did this. For this video I just used the instructions at the link in the description and was a bit surprised at the result. Thanks for the advice on that.
@@PCRetroTech Hehe... your video pushed me to look into it - I figured it had to be possible to do it "correctly" given how many options GIMP has, but had never bothered to check... I've been playing with photo display methods on CGA and Plantronics recently, and this discovery might help.
It's slightly annoying I didn't realise this when I made the video. Various thoughts along the lines of, "those colours seem awful close together in the end, that can't be right", occurred to me along the way. But I rushed through it to get the video out in time....
@@PCRetroTech Please sticky widicamdotnet's comment.
Yeah! I used to use Paint Shop Pro back when it was a Jasc product, and remembered using the optimized palette feature to create GIFs for my web site, since it was the only way to do transparency. At least in MSIE until, I dunno, a year ago or whenever it started supporting PNG.
Edit: This probably wasn’t clear to anyone not experienced with graphics formats. The point of using the optimized palette was so you could clone that palette across multiple graphics assets that would all be reduced from True Color originals to a single, site-wide palette that would look right even when displayed in 256 color mode. But also because even in higher color res, the GIF format of course was limited to an indexed palette anyway.
A good stable and fast imitation of Floyd Steinberg dithering is precomputed blue noise overlay. People have been working on magical spatiotemporal blue noises recently as well.
Interesting reference! Thanks for the info.
Who else lived a Hercules life in a CGA/EGA/VGA world? I didn't just see dithering, I LIVED it. Everything was dithered! From CGA emulators to Space Quest 3 (The start in the dump I couldn't see what the hell was going on! But I finished it eventually, ha ha.) and VGA images dithered down to a monochrome death. If you squinted your eyes from a few metres away, you could imagine it looked good. Good days though. I'm glad I grew up in that era where graphics and technology rapidly advanced and we were taught to program computers and not just use them like today.
That era led to a certain proportion of the population learning to actually do stuff. I guess the later generations had arduino and minecraft computers.
Defender of the Crown probably has the best graphics on most of the systems it was released on.
I have the C64 version, and whilst it was a loading nightmare(it come on 2 audio cassette tapes, and you'll be switching tape/side quite often, with some load times in excess of 2 minutes) it looked amazing. It made full use of all 16 of the C64's colours and had great dithering.
Great video - some of the most impressive examples of algorithmic (not pre-computed) dithering from VGA through EGA all the way down to CGA that come to mind are Golden Axe, Metal Mutant and Budokan
Oh interesting. The first two I was not aware of. And I had just recently been wondering about algorithmic dithering.
Back years ago I did a Floyd-Steinberg dither converter for GIF images that output to an ink jet printer.
It also worked quit well in hi res low color depth PC graphics modes. This was in the time frame graphic cards only supported 256 colors in the lowest res modes.
There is a standard algorithm that down converts the color pallet, but I can’t remember the name of it.
Those images look amazing on the CGA monitor!
Yeah, the original monitor makes a huge difference in my opinion.
pretty amazing review of todays effort mimicing old school graphics
I really love the look of 16-color high-res VGA games. Games like Darkseed and various PC-98 ports look incredible on a CRT monitor, the scanline effect is awesome. Darkseed actually runs in EGA 640x350 resolution with a VGA palette, I think it can technically run on an EGA display but everything looks pretty messed up.
Ah that explains it! I thought it looked too good to be normal EGA!
You got more than 500 likes. You're on the hook now! 😉Love your channel.
So I did! I guess I had better put it on the video schedule. I'd completely forgotten about this.
@@PCRetroTechcan’t wait to see it
i remember Sonic doing some dithering tricks to exploit the crt monitor characteristics. i think it was to achieve transparent waterfalls. transparency was not really a thing on the early consoles
Interesting. I've not looked at console hardware much, but I've seen a few videos on some of the tricks that were used.
Thanks for explaining several basic dithering techniques, and yeah, 16 colour dithering is completely new level in comparison to 4.
Yeah it's a real eye opener.
I’m curious why this wasn’t more popular. Loom made waves with their EGA release looking like VGA, but I remember most of the EGA stuff looking very flat colored. I’m thinking of Home Alone, which I ran once on a friend’s Tandy, and the digitized photos in the cut sequences were ghastly.
Even 256-color VGA graphics weren’t that well dithered unless they were hand-painted like all the Sierra stuff. It wasn’t really until Myst that the result looked like a slightly grainy version of True Color.
I guess it took a while for someone to come up with sophisticated dithering algorithms? I mean, sheesh, remember the Windows color picker dialog? It managed to make VGA look like EGA. I assume Windows used something cheap and fast like halftone dithering though.
0:57 here is my project, Castle of Viana :)
I did play around with some dithering while working on it.
It was actually positional dithering applied in load time, effectively offering ~12 colours.
In my case, I would first use Inkscape to tweak and recolourise the images, then use GIMP to dither it.
The process wasn't all that smooth, but it didn't need to be all that amazing: The only real photo used was for an Easter egg dedicated to my wife.
Nice!
Famicam 64 is a camera app for iOS. Also, don't forget the Tandy 1000 series could also do all sixteen colours at once at 320x200.
Ah thanks
Great video -- I can't believe what you can get with dithering on those old CGA cards. Love the beanie too :-D
I'm more of a Point or Positioned dither proponent because it's more compatible with traditional pixel art techniques and easier to rotoscope, break down into tiles, and layer composite. The other methods of dithering treat the image more as a whole where you can't really segment or optimize per screen block palette limits.
CGA is a very interesting video platform, the traditional graphics, the background color vertical gradient trick, the Composite artifact colors, the 160x100 16 color mode, just a big box of options. :D
It's quite a bit more flexible than it seems at first sight.
Amazing work!
Monkey Island! Marc Ferrari did an awesome job in the original EGA release.
Congratulations on Your Mum programming skills!
This ditherton looks very promissing!
I'm gonna use it for my Amiga workbench backdrop :D
aww, thanks mom! :D
Hurray for you mommy! Nice work!
Good video , also get yourself a good channel icon art.
Thanks for the tip
more dithering! :D
I vote Space Quest III having really good EGA dithering!
I actually considered putting this in, and probably should have done. Truth be told I ran out of time due to some technical issues.
Great content! Love EGA graphics. If you're looking for brilliantly dithered EGA games check out Loom and games like Timequest and other (early) adventure titles released by Legend Entertainment. Their pixel art was the best imho as they squeezed everything out of what (enhanced) EGA had to offer: 640x350 and perfectly selected 16 out of 64 color palettes with dithering 👍👍
Indeed. I check out Loom in a later video.
@@PCRetroTech Cool, I haven't seen that one yet. I'll be sure to watch that one as well 😎
Cool video. Impressive what can be done when resources are limited
640x350 EGA mode would have been even better. Ah, you didn't have access to real EGA monitor. Maybe later then.
I think in one of the next few videos on the channel I did some dithering on a mode 2 EGA monitor.
Have you seen CGAArt by reenigne and the video "Time-lapse CGA pixel art (8088mph)" by x86VileR?
I've certainly seen x86VileR's video. Unfortunately CGAArt didn't work on my machines due to some problem with Microsoft Redistributables which they must have somehow changed since Reenigne made that program. I did try to get it going for this video, as I was certainly aware of it, but I just wasn't able to get it working in time.
@@PCRetroTech That's odd. It works on my Windows 11 machine, but the first time I run "cgaart rose.png" it takes half a minute to start the program.
@@DookNookim Interesting. I don't know what was going on then.
I just saw this...an 1981 IBM PC 4,77Mhz, CGA, 640KB memory and the team that have made it is working hard to fit it in a single 360KB disk if you can believe it.
ua-cam.com/video/-xJZ9I4iqg8/v-deo.html
40 years later and we are still discovering what those machine were really capable of
I was one of the people responsible for this. Take a look in the Credits for UtterChaos at the end. I greet PCRetroTech!
@@PCRetroTech Kudos to you! An amazing accomplishment. I cannot help myself thinking what IBM folks would have to say about such amazing demo back in 1981. If anything they would recognize they knew nothing about their own machine !
@@emersonlopes83 Yes, I can imagine their faces. They knew about using text mode to get an effective 160x100, albeit with snow. But much of the rest of it would have been a mystery to them I think.
you might look into the dithering used in Loom.
Awesome, I'll check it out! Thanks.
Yeah that game looks AMAZING! At first I was convinced it was VGA. I've never seen it before. If I had, it definitely would have been my first choice for this video!
@@PCRetroTech yeah Mark Ferrari was behind it, there are some pretty interviews out there where he discussed it. I recall one with Retro Cave (RMC)
Yeah. The actual VGA version is gorgeous, but there’s a well known factoid floating around that Mark had been advocating for more dithering in the EGA graphics, but the technical guys vetoed it because it didn’t compress well, and so took too much disk space. (Floppy distribution and all, you know..)
So in protest, he hand dithered a couple scenes and left them on his screen while taking lunch. Came back to the tech guys and the director(?) having a conversation by his desk, “so why _can’t_ we compress dithered graphics?” Haha
Mark Ferrari talking about his techniques with a lot of examples: ua-cam.com/video/aMcJ1Jvtef0/v-deo.html
It's still #DOScember, right? I bet you could get a few more views if you added that tag to the description. I mean, this qualifies, doesn't it?
I thought about it, but I don't think anyone is doing those themed months any more.
@@PCRetroTech Hm, maybe you're right. It was just a thought.
@@PCRetroTech That would be a shame. I hope it gets going again.
more Plantronics stuff is needed :)
You completely missed the point of those purple CGA graphics..
Search for the video titled :
"CGA Graphics - Not as bad as you thought!"
you might learn a thing or two.
Funnily, some 8bit machines had somehow better graphical capabilities than the CGA, namely the amstrad CPC... from a basic CGAesque "Mode1" in 320x200x4 your could go full screen (384x256), have various "raster" palette changes on the screen (change inks for the next lines), set each 4 inks from 27 colours, perform some 25hz palette/screen flipping to soften some ditherings or add extra colours. But those machines also lacked RAM and CPU power to run proper 16bit games such as Populous (being 8bit machines). But the 320x200x4 can really displays some great Pixel arts if only the fixed palettes of the CGA could get more freedom...
EGA's 640x350x16/64 mode often feels like some untapped potential awesomness and the Demoscene and Pixelart community should really give it some more love, but the strange pixel ratio and limitations and current rarity of the format won't help.
A shame CGA and EGA lacked some decent character attribute graphical modes or CGA being sooo lackluster in palette/ink customisation (could only custom set the background ink ? srsly ?). Some colours from the palette were never to be seen by the average young gamer with a CGA computer. The 640x200 modes in 16 (or even 4 ) colours also have some massive untapped potential but EGA would often get bad case of very heavy scanlines in "vertical 200 pixels" modes (on EGA HD monitors especially).