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Consolemu
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Color Depth (Ideas on it)
 Posted: Sat May 20, 2000 9:23 pm
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This is another topic that's of my contern when it comes to emulation. Most people don't even notice this but I do. Why are so many emulators emulated for 256 color depth when in some cases it needs more. For instance, 256 is perfect for the Nes, but shouldn't it not be used for systems like the Genesis or Turbo Graphix 16? Don't those systems deserve larger color ranges for brighter graphics and better gradient effects? I notice with a lot of games the the graphics look dark and dull, like the game is trying to access colors outside of the 256 range but the hardware can't handle it. Correct me if I'm wrong but doesn't the Turbo Graphix 16 use a brighter and larger color pallete; kind of like the Snes does? And from me personally, I think the colors that many genesis emulators use are a bit off. Don't they all seem dark and dull or is this just my imagination? When I see it on my TV it looks clean, bright, and vibrant. When I see it on my monitor it looks dull. My brightness and contrast is fine. My monitor is an IBM G40. Is it emulation or my monitor?
Chris :o)
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vecna
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Posted: Sun May 21, 2000 2:42 am
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The Genesis can only display 64 colors at a time, so it fits in a 256 color mode. Well... almost. Except that on the genesis you can change the palette during raster effects, making it possible to have more than 256 colors; which is why KGen98 for instance, would run in 256 color mode or hi-color mode, but in 256 color mode it wouldn't emulate palette-raster effects (namely, the water on Sonic the Hedgehog, and stuff like that).
The SNES can obviously have more than 256 colors due to the layer addition/subtraction thing. Many SNES emulators support multiple color depths.
The PC Engine/Turbografx has a total palette of 512 colors, but it can't display them all at once.. I forget how many total colors can be onscreen at once, but it's some odd number like 468 or something weird like that. Most of the time, less than this are onscreen at a time, so they can get away with only displaying 256 colors at a time. However, it defintely would be cool to use highcolor for PCE.
CHASMS actually ONLY uses highcolor modes, just because of the way I designed the video driver I originally wrote for Windows. on the SMS it's a bit overkill, since it can only display 32 colors at a time. I intend to hack in an 8-bit mode for it in the next version hopefully, but we'll see.
The main reason emulators have traditionally used 256 color modes is, well, in DOS they're by far the most universally compatible and easily accesable, and also, speed. 16bit color is twice as much data per frame (possibly more like 4x, depending on how your rendering system is set up), and 32bit color is accordingly 4x as much data as 8-bit (again, up to 8x or even more). So speed begins to be a bit of a concern.
I'm possibly going to make a windows PCE emulator after CHASMS, and I'll definitely do it high-color only. On the SMS I can justify hacking an 8bpp mode for speed reasons, but not if I have to reduce the video quality.
Regarding overall brightness and vibrance of the palette, part of that may be emulators that don't convert the palettes 'correctly'. Actually, SMS emulators are a great example. Look at the colors on MEKA, Calypso, or SMS Plus and compare to CHASMS, Massage, or Darcnes. Here's why:
The SMS palette is 6-bit color depth, 2 bits for each pixel. So, lets say the color 11 11 11 on the SMS, which would be the brightest white. The 'normal' way to convert this is just to multiply (or shift). When you do this, however, the values you get are 11000000, 11000000, 11000000. That's obviously not full white. The way to get the vibrant colors is not to multiply, but use a precomputed table, that makes sure that 11 translates into 11111111, and not 11000000, and makes sure everything else in between fits accordingly.
- vecna
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Consolemu
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Posted: Sun May 21, 2000 12:57 pm
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Quote > The Genesis can only display 64 colors at a time, so it fits in a 256 color mode. Well... almost. Except that on the genesis you can change the palette during raster effects, making it possible to have more than 256 colors; which is why KGen98 for instance, would run in 256 color mode or hi-color mode, but in 256 color mode it wouldn't emulate palette-raster effects (namely, the water on Sonic the Hedgehog, and stuff like that).
Also, I see a difference in the shading techniques like in Space Harrier 2 and Batman 2. But still, the graphics all look dull. Look at streets of rage on the real system and then on any emulator. You'll see a difference.
Quote > The SNES can obviously have more than 256 colors due to the layer addition/subtraction thing. Many SNES emulators support multiple color depths.
Exactly. SNES get's mad respect...all others are just slopped together. j/k :o)
Quote > The PC Engine/Turbografx has a total palette of 512 colors, but it can't display them all at once.. I forget how many total colors can be onscreen at once, but it's some odd number like 468 or something weird like that. Most of the time, less than this are onscreen at a time, so they can get away with only displaying 256 colors at a time. However, it defintely would be cool to use highcolor for PCE.
Would you like me to name some games that are dark and dull and colors are meshed to others? Splatterhouse, Dracula X, Ninja Spirit. Oh, here's something that's funny. Genpei 1 (Samurai Ghost) looks dark and dull; like it tried to use bright colors. But, Genpei 2 (Samurai Ghost 2/Samurai Ghost (US)) looks bright and clean. Shinobi (Some scenes), The 5 in 1 Famicom Collection (Colors are way off), Ghouls 'n Ghosts (Colors look meshed). There are quite a few games that look good but others look strange.
Quote > CHASMS actually ONLY uses highcolor modes, just because of the way I designed the video driver I originally wrote for Windows. on the SMS it's a bit overkill, since it can only display 32 colors at a time. I intend to hack in an 8-bit mode for it in the next version hopefully, but we'll see.
> The main reason emulators have traditionally used 256 color modes is, well, in DOS they're by far the most universally compatible and easily accesable, and also, speed. 16bit color is twice as much data per frame (possibly more like 4x, depending on how your rendering system is set up), and 32bit color is accordingly 4x as much data as 8-bit (again, up to 8x or even more). So speed begins to be a bit of a concern.
> I'm possibly going to make a windows PCE emulator after CHASMS, and I'll definitely do it high-color only. On the SMS I can justify hacking an 8bpp mode for speed reasons, but not if I have to reduce the video quality.
Well, you still need 8-bit modes for the slower machines but hell, make it the user's choice. 8 or 16.
Quote > Regarding overall brightness and vibrance of the palette, part of that may be emulators that don't convert the palettes 'correctly'. Actually, SMS emulators are a great example. Look at the colors on MEKA, Calypso, or SMS Plus and compare to CHASMS, Massage, or Darcnes. Here's why:
Hate to interrupt but...Massage looks dry, SMS Plus looks dry, and Meka...It looks okay when you set the pallete bright in the config file.
Quote > The SMS palette is 6-bit color depth, 2 bits for each pixel. So, lets say the color 11 11 11 on the SMS, which would be the brightest white. The 'normal' way to convert this is just to multiply (or shift). When you do this, however, the values you get are 11000000, 11000000, 11000000. That's obviously not full white. The way to get the vibrant colors is not to multiply, but use a precomputed table, that makes sure that 11 translates into 11111111, and not 11000000, and makes sure everything else in between fits accordingly.
I've never had a change to do programming for 16-bit video modes but I do know for a fact that under 256 if you send 11000000 to any one of the RGB sets the intensity will wrap around back to the darker colors (It might wrap like 2 or 3 times depending on how large the number is). There's only 63 intensities per primary color. But, even if the color is shifted less to fit for 8-bit, like this...00011000 (48), that's still not the brightest color. 63 is the brightest color. I assume that meka keeps it like this for the darker pallete and adds 16 to make the brighter pallete effect. I don't really have any complaints with Meka's colors though. Meka's is good, yours is very good (I don't know what it is), but it's the other systems I have problems with.
PS. Does your emulator use a pre-calculated color table, as you described in your theory?
Chris :o)
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Limbs a Flyin'
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Posted: Sun May 21, 2000 2:00 pm
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[snip]
sometimes colours look odd because the emu author doesnt calculate colours correctly. eg genecyst, bright white is not as bright as it could be.
heres my guess why that is:
author understands that a single vga palette entry uses 6bits per channel (per r,g and b) which means 64 possible values.
author understands that genesis video palette entry uses 3 bits per channel, which is 8 possible values.
so 64 vga intensities / 8 genesis intensities = vga channels should increment in steps of 8
which isnt correct, because the max value of genesis intensities would be 7, and 7*8 gives you 56, which is duller than 63.
math should have been like this
63 (actual max intensity obtainable)/7(ditto) =steps of 9
7*9=63
think about that when you toggle the brighter palette option in meka (it originaly had dark colours, but i am slighty responsible for the brighter colours idea)
other things that should be taken into consideration (but usualy never are) are things like poperties of monitor phosphers Vs. tv phosphers (often give different brightnesses/colours) and gamma correction. i forget the math, but gamma correction helps brighten up (or darken down) your mid range colours - massage does this (was this intentional?) and makes its over all appearaence brighter.
gamma correction trys to cover for the fact that phospher dots dont linearly grow in intensity (which is why most photos on peoples sites look dark! copy and paste into a graphic editor, give it a good gamma correction of say 1.5 and things are more natural looking)
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- Joined: 28 Sep 1999
- Posts: 1197
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Posted: Sun May 21, 2000 5:28 pm
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Quote > Also, I see a difference in the shading techniques like in Space Harrier 2 and Batman 2. But still, the graphics all look dull. Look at streets of rage on the real system and then on any emulator. You'll see a difference.
At least with the Genesis, there's a few different things at
work to give the appearance of more colors:
The Genesis (and SMS) have exceptionally blurry output. You've
probably seen this in any game where bright reds are next to
another color, and the 'mix' together a bit on screen.
Many Genesis games will put alternating vertical stripes of
colors together, and due to blurriness it appears as a new
color. The Sonic games do pseudo-transparency using
this trick.
Also, the Genesis has a special display mode that boosts the
on-screen colors to nearly 192 colors, which is what you
saw for the shading in Space Harrier II. But not many games
use it, since there are some big restrictions on use.
Quote > Would you like me to name some games that are dark and dull and colors are meshed to others? Splatterhouse, Dracula X, Ninja Spirit. Oh, here's something that's funny. Genpei 1 (Samurai Ghost) looks dark and dull; like it tried to use bright colors. But, Genpei 2 (Samurai Ghost 2/Samurai Ghost (US)) looks bright and clean. Shinobi (Some scenes), The 5 in 1 Famicom Collection (Colors are way off), Ghouls 'n Ghosts (Colors look meshed). There are quite a few games that look good but others look strange.
>
Belive it or not, this is entirely due to how clever the
artists are. The PCE can show a lot of colors, but if the
artists aren't using the palette efficiently, then any
advantage is wasted. Some PCE games do have very nice and
vibrant graphics, like Blue Blink.
Quote > Hate to interrupt but...Massage looks dry, SMS Plus looks dry, and Meka...It looks okay when you set the pallete bright in the config file.
SMS Plus doesn't compensate for proper brightness like vecna
was talking about (the shifting thing). After reading this
thread, I'm going to add a brighter palette option in the
next version, since it sounds like people want nicer
colors. ;)
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