[Coco] Artifacting (again)

[Mark McDougall]

On 3/09/2010 12:48 PM, Robert Gault wrote:

> Don't get confused by the output of emulators. There is only one emulator
> that comes close to correct artifact appearance, MESS. The Keil, and VCC
> emulators approximate the artifact effect by using pure white, black, red,
> and blue but these are not artifacts. As a result of this graphics on these
> emulators will look sharper than the same screen would be on a real Coco
> attached to an NTSC monitor.

Yes, I understand that. It's just that keil's emulator obviously has a more 
complicated algorithm than the simple pixel-pair one I'm using, for the 
reasons I outlined. And I would assume that it's somewhat closer to the real 
things than mine, though not as accurate as MESS.

I've taken a quick look at the MESS code and I'm afraid it's way too complex 
for my requirements. I was looking at a middle-ground between the simple 
pixel-pair and the real thing.

The other option that my colleague has suggested is to do a colour-space 
conversion to YCrCb and then filter the signal in a manner that simulates 
the bandwidth of a CRT. That's a lot of work but would at least be 
interesting to try! ;)

FWIW I hooked up my Coco 3 to a TV today and realised that the PAL output 
does not artifact nearly as "effectively" as the NTSC output I've seen. I 
vaguely seem to recall people lamenting that fact in the past?!? PAL gives 
little more than orange and purple fringes on pixels, certainly not the 
effect that was originally programmed for.

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"