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AuthorTopic: Dithering  (Read 271 times)

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Offline trekiej

Dithering
« on: September 24, 2014, 05:25:29 PM »
I noticed a long time ago that he C64 could get about 128 k colors by dithering.
I saw this either in compute magazine or Loadstar.
Could the other CBM machines do this, specifically the TED chip?
Amiga 2000 Forever :)
Welcome to the Planar System.
 

Offline Hattig

Re: Dithering
« Reply #1 on: September 24, 2014, 06:01:58 PM »
Not every colour dithers well, and IIRC it only works in one of NTSC or PAL effectively.
The other issue is that the C64 has limitations on the colours that can be on screen.

Some games went the other way, and switched palettes rapidly to get extra colours in sprites, etc, such as cyan.
 

Offline Thorham

Re: Dithering
« Reply #2 on: September 24, 2014, 06:58:58 PM »
On the Amiga you can alternate between two images with different palettes to get dithering. Al you need is a suitable frame rate, and some software to convert an image to this format. They have some of this stuff on the Atari ST (special color modes like on the C64).

You can also do interlace based dithering. Works well enough in 50 hertz interlace, but with AGA you can increase the screen refresh rate to things like 94 hertz interlaced (works great on SVGA CRT monitors), and that will make interlace dithering even more effective.

These kinds of dithering may also work on the peecee (perhaps to get ten bits per color channel on eight bits per channel hardware).
 

Offline trekiej

Re: Dithering
« Reply #3 on: September 24, 2014, 07:27:35 PM »
From what I remember, the chart showed a 16 x 16 grid. That would make 256 colors. It also showed how some colors did not work or show.
It also seems to that one needs to include the LUT or color palette.
The article stated that it would switch out two colors rapidly. Would this affect frame rate? I wonder if 3 or more colors be switched out.
Thanks.
Amiga 2000 Forever :)
Welcome to the Planar System.