Full-Screen Dithering on the PSX?

[kool kitty89]

I recently saw this term come up and Sheath explained it to me, or at least showed an example of what it refers to here:
http://www.gamepilgrimage.com/content/tomb-raider-2

And a related discussion here:
http://sega-16.com/forum/showthread....465#post320465

But I'm really not sure what's going on and it's really odd. It looks like some sort of dynamic dithering going on but I'm not sure how (GPU?) or why it's done. (supposedly it saved VRAM)
The first thign I thought of was some sort fo hardware interpolation of a highcolor display to an 8bpp framebuffer to use less space, but I've never heard of anything like that on the PSX.

Does anyone know more on this?

[tomaitheous]

Yup, I knew about the PS1 dithering BITD. I had bought an s-video cable for PS1, after having put down $800 for a new TV (expensive for back then). I couldn't believe how horrible it looked. I don't think I use the cable much after that experience. Composite might not have been as sharp, but you didn't see any dither.

Also, GPU's on PCs did this as well. They auto down colored by hardware dither. ATI Rage chipset was one of them, IIRC.

[sheath]

Well, so far this is the first time I have brought this up and not been brow beat for it. I play PS1 and Saturn games in S-video because I like the colors better, and some games' texture mapping really shines in S-Video. Even on my old SDTV the number of full screen dithered PS1 games was obvious.

I also find it odd that everybody knows about the Saturn using dithered transparencies, which only show up as a moire effect in Composite, but relatively nobody seems to know how many PS1 games dither the whole screen.

[kool kitty89]

Yup, I knew about the PS1 dithering BITD. I had bought an s-video cable for PS1, after having put down $800 for a new TV (expensive for back then). I couldn't believe how horrible it looked. I don't think I use the cable much after that experience. Composite might not have been as sharp, but you didn't see any dither.

Also, GPU's on PCs did this as well. They auto down colored by hardware dither. ATI Rage chipset was one of them, IIRC.

Oh, interesting, I don't remember my RAGE Pro ever doing that, but maybe we never had it configured for such. (it would definitely be really obvious in VGA compared to an SDTV... even if you were running at 640x480)

Do you know if it was specifically aimed at 256 color output, or also used for 24-bit interpolated to dithered 15/16-bit color?

It definitely seems like an odd way to go IMO since plain non-dithered 256 color renderers generally look better with the exception of smooth shading effects. (and dithered gouraud shading WOULD be the one area that such effects should have been used -not just in 256 color but in highcolor and even truecolor, in all cases to smooth out the posterized banding, but that's most extreme at lower color anyway; given textured surfaces rarely used smooth shading that generation, such dithering would largely be limited to those untextured surfaces -X-Wing CD and Tie Fighter used dithered shading rather nicely especially with the 640x480 mode of Tie Fighter, a shame more 256 color renderers didn't give that as an option at higher detail; Tomb Raider in particular looks pretty good in 256 colors but the shading on untextured surfaces is really posterized)

Well, so far this is the first time I have brought this up and not been brow beat for it. I play PS1 and Saturn games in S-video because I like the colors better, and some games' texture mapping really shines in S-Video. Even on my old SDTV the number of full screen dithered PS1 games was obvious.

I also find it odd that everybody knows about the Saturn using dithered transparencies, which only show up as a moire effect in Composite, but relatively nobody seems to know how many PS1 games dither the whole screen.

Yeah, it's really odd that it hasn't come up before, especially from PAL users with RGB (making it even more obvious).

And on the Saturn: a couple cool things about that is that 2 of the resolution modes (352 and 704 wide) are direct multiples of the 3.58 MHz NTSC color carrier and thus you don't get the banded moire like the MD in 320 wide mode, but instead you have very solid and consistent artifacting (same for S-video), so you don't get the funky rainbow artifacts that move as the dithered patterns move, but sold artifacts without alternating colors. (of course that won't apply to PAL as the color carrier is higher -though that alone means the 320 wide mode of the MD and Saturn is more like the artifacting of the 256 wide mode of the Genesis and SNES -etc- in NTSC -by the time you get to the 640/704 wide modes it's going to have artifacting in PAL anyway, at least with the common video encoders being used at the time, but for the 704 wide mode you get solid artifacts with the 14.32 MHz dot clock)

[OldSchool]

What does "dithering" do, guys? I'll save my googling and simply ask y'all.

Is there some kind of negative effect from using S-Video for the PS1?


I'm so lost.

[j_factor]

I would just like to take credit for the fact that I mentioned this issue back in 2008. Twice.

I've always noticed it, but then again, I always used s-video for PSX, and so did my friend who got one at launch (he might not have had an s-video cable immediately, but he got one relatively soon).

[kool kitty89]

What does "dithering" do, guys? I'll save my googling and simply ask y'all.

Is there some kind of negative effect from using S-Video for the PS1?


I'm so lost.

It's what makes Sega CD FMV and many GIF images have that "grainy" look and there's several types, but in the PSX's case it seems to be (unsurprisingly) simple pattern dithering (see Bayer Dithering on wiki)
http://en.wikipedia.org/wiki/Dither

Also see: http://www.gamepilgrimage.com/content/tomb-raider-2

and:

PSX v 1.7 emulation shots:

I couldn't figure out how to blow them up with BB code.
Soul Reaver:




Warhawk:




S-video Shots:

Gran Turismo:
















Gran Turismo 2 looks the same, and I've got quite a few other S-Video shots that are this obvious that I haven't relinked since the site transition.

Again, I think dithering is preferable for smooth sharing effects, but otherwise (for realtime 3D) it's preferable to stick to plain 256 color textures/shading. (maybe plain checkerboard dithering for some flat shaded untextured surfaces) 16-color is another story, but if you're on a system stuck with 16 colors you're probably not going to have the resource for such dynamic dithering anyway. (other than simple paired pixel rendering like Duke Nukem 3D and Zero Tolerance on the Genesis -Road Rash and Skitchin use that too)



Interestingly if you watch youtube (or some other streaming videos) with windows in 256 color paletized mode, there's dynamic error diffusion dithering interpolating the highcolor/truecolor video to 256 colors. Actually it seems that flash in general seems to use that method. (kind of fun to play around with)
Edit: and windows media player clasic also does it. (dynamically as well, with low priority if you're moving other things around while the video is playing or adjusting the video window, but with the video window left alone playing it sets to an optimized palette with higher-res dithered interpolation -in fact I think it might be sticking to the 16 color RGBI palette when non-optimized, something a lot of programs tend to do in 256 color mode)

Scratch that on media player classic: it seems that I may have been viewing a 256 color encoded video in the case where it optimized the palette automatically. (Sonic CD's PC cutscenes do that too, and the initial video I tested was Sheath's Need For Speed comparison video, so maybe that's encoded in a 256 color format??? The other comparison videos don't do that and neither do other videos I've downloaded -just simple dithered interpolation albeit far better than what other players do in 256 colors -simple posterization to RGBI)

[OldSchool]

That Warhawk games looks really fun! I wish I could get it.



Sucks that it doesn't support the Analog Sticks according to what I read on the Wiki entry.

Damn, the remake looks terrible.

http://en.wikipedia.org/wiki/Warhawk_(2007_video_game)

[kool kitty89]

Yes it's a neat game as are the Colony Wars games.

It predated the anlog controller and wasn't among the games to use the flight stick (I think the PSX has a flight stick... I know 3DO and Saturn do).

I don't think it's uncommon so you should be able to pick up a real copy. (for play on PS2, PS3, PSX emu on PC, or PS1 -I forget if you own a PS1)

[OldSchool]

Yes it's a neat game as are the Colony Wars games.

It predated the anlog controller and wasn't among the games to use the flight stick (I think the PSX has a flight stick... I know 3DO and Saturn do).

I don't think it's uncommon so you should be able to pick up a real copy. (for play on PS2, PS3, PSX emu on PC, or PS1 -I forget if you own a PS1)

I can't stand playing games with the D-Pad as the Movement Controller... hurts my thumbs after mere minutes of playing. I require the Analog stick. It's why I had to take Alien Trilogy (PS1) out of my collection. Neat old FPS but it's absent Analog support... I made it 10 mins before my thumbs were throbbing.

If I can't control a game with a M&KB, then I need Analog support... unless we're talking NES/SNES/Genesis, those D-Pads rock.

[sheath]

Warhawk absolutely rocks. I recommend it to every Playstation owner.

[tomaitheous]

Oh, interesting, I don't remember my RAGE Pro ever doing that, but maybe we never had it configured for such. (it would definitely be really obvious in VGA compared to an SDTV... even if you were running at 640x480)

Do you know if it was specifically aimed at 256 color output, or also used for 24-bit interpolated to dithered 15/16-bit color?

Yeah, the Rage series did it (along with other chipsets from that era), but it's very slight.

I don't know if you could turn off the feature in PS1, but I'm assuming you can. I don't particularly remember seeing it on 2D games (which isn't a different mode than 3D games). And being a hardware effect, I wouldn't doubt that the PS2 'enhance' gave full color bandwidth for those modes. AFIAK, the playstation emulators don't emulation the dither - so you get nice high color output. But I doubt the original is meant for 256 color output. That's just way too low. Probably around 15bit color (which still produces a lot of banding for some color ranges and dark colors).

I also find it odd that everybody knows about the Saturn using dithered transparencies, which only show up as a moire effect in Composite, but relatively nobody seems to know how many PS1 games dither the whole screen.

Because it's not quite the same thing.

[sheath]

ePSXe doesn't emulate the dithering, it enhances everything even with all effects off. PSX Emulator v1.3 and 1.7 show what looks like low level emulation though.

[sheath]

I would just like to take credit for the fact that I mentioned this issue back in 2008. Twice.

I've always noticed it, but then again, I always used s-video for PSX, and so did my friend who got one at launch (he might not have had an s-video cable immediately, but he got one relatively soon).

I wholeheartedly agree with your previous posts. Dev kits, marketing, and journalistic vulture action got the Saturn labeled "bad" at 3D, not the games themselves or the hardware.

I think most of the internet speculation about the difference between the PS1 and Saturn is loaded Sony's way by the PS1's dithering though. The dithering filters the textures somewhat and that contributes to the constant conclusions that the PS1 "looked smoother".

All I really needed to see was the PS2, 360 and PS3 succeed on the market place to know for certain that the Saturn's design was not more flawed.

[lumclaw]

I wholeheartedly agree with your previous posts. Dev kits, marketing, and journalistic vulture action got the Saturn labeled "bad" at 3D, not the games themselves or the hardware.

I think most of the internet speculation about the difference between the PS1 and Saturn is loaded Sony's way by the PS1's dithering though. The dithering filters the textures somewhat and that contributes to the constant conclusions that the PS1 "looked smoother".

All I really needed to see was the PS2, 360 and PS3 succeed on the market place to know for certain that the Saturn's design was not more flawed.

Indeed. Internet fandom has always been flat wrong about that "war". Bottom line is Saturn had better 3D, and PS1 had better 2D. No matter how many trolls may want to hang my head on their wall for saying it.