My findings of 16-bit CrY mode

[JFD62780]

Okay, I sorta bumped into something while surfing the Jag forums, mentioning that fabled CrY mode, which I've first seen mentioned in one of my earlier topics, about that Tempest 2000 emulator.

 

Problem is, when I've seen 16-bits attached to it, my stuck-in-the-past brain thought it was the 5-6-5 RGB mode that was meant. Then I read further into it and came to a conclusion:

 

16-Bit CrY IS the next evolution in color libraries for the Legacy Atari Systems!

 

No, really, hear me out on this:

• The TIA of the ORIGINAL 2600 was 7-bit CrY, that is 4-bit chroma, 3-bit luma (16 hues, with 8 shades each).
  
• While the 5200, 7800 and 8-bit computers ran on 8-bit CrY, 4-bit chroma, 4-bit luma (16 hues with 16 shades).
  

 

The Jag takes it a full-byte further with this: 16-bit CrY is 8-bits chroma and 8-bits luma! Meaning a full 256 hues with 256 shades each!

 

What those hues are, damned if I know! No wonder I thought T2K looked 24-bit! o.o

Edited February 20, 2010 by JFD62780

[kskunk]

The Jag takes it a full-byte further with this: 16-bit CrY is 8-bits chroma and 8-bits luma! Meaning a full 256 hues with 256 shades each!

 

What those hues are, damned if I know! No wonder I thought T2K looked 24-bit! o.o

Nice observation! I never thought of it that way.

 

It's true the earlier 8-bit Ataris had a "hue" nybble. But only hue could be selected, not chroma.

 

The Jaguar's CRY mode is unlike earlier Ataris. The CRY byte is more of a "color" selector, not a hue selector. Both hue and chroma are controllable by that byte, but not directly. Instead, the RGB value of that color is selected by the byte from a table.

 

Here's a picture of the CRY color byte table:

 

As you noticed, this results in very smooth shading with somewhat blocky color blending. It's a good compromise in certain games, especially Doom, which looks just GREAT in CRY.

 

- Ks

[philipj]

Looks like mode x style graphics from the old DOS days... CRY files do seem small in file size. Are you suggesting that CRY can possibly work on other systems besides the Jaguar?

[Zerosquare]

Your picture looks a bit strange kskunk

 

Here are the 256 shades with the maximum intensity :

 

And what it would like if the color space were continuous :

 

CRY is a bit like luma/chroma indeed, but there are differences. In particular, the Y channel in CRY is max(R, G, B), instead of a weighted average. For instance, pure blue is considered as bright as pure green, while in reality it appears much less bright. This makes CRY less well-suited to the human visual system, compared to YIQ or YUV luma/chroma which was used on 8-bit Atari consoles and computers. But it works fine for Gouraud-shaded graphics, which was the design goal.

 

(By the way, Atari didn't choose luma/chroma for the 8 bits because of the visual properties, but because it made the graphics hardware simpler, since composite NTSC and PAL is based on it. That's also why the SECAM 2600 has so few colors, as the color encoding is different and less suited to such methods.)

[JFD62780]

Looks like mode x style graphics from the old DOS days... CRY files do seem small in file size. Are you suggesting that CRY can possibly work on other systems besides the Jaguar?

 

heh, if that were true, I suggest to the makers of ZDOOM (Software, not Graf Zahl's GL-based version) to make a CrY-simulator to support the 32-bit graphics mode, based on how it would've been used in JagDoom. IF it was. ;D