Re: Help needed with HyperStudio

[spec@vax2.concordia.ca (Mitchell Spector)]

In article mikew50@aol.com (MikeW50) writes...

>In message <872296145.170403@pasteur.dialix.com.au>,
>df@adelaide.dialix.com.au (David Francis) said:
>>There must be a way to get over this problem because I found a Star Trek
>>stack on the net which has b & w photos of the main Enterprise bridge
>>characters superimposed on a coloured background.
> 
>Actually, there are some tricks, but fundamentally your Apple IIGS doesn't
>want to display any more than 16 colors on a single scan line in 320 mode.
>I'm not sure what you saw, but here are the possible ways to mix gray
>scale pictures with colored background pictures:
> 
>1. Don't use a full 16 shades of gray. (Some are too close to distingush
[snip]
>2. Mix the scan lines. While 320 mode graphics must use a particular 16
[snip]
>3. You can use 3200 color dispay. This does some very tricky stuff to
[snip]
>4. Do some custom programming and use a Second Sight card to display 256
[snip]

    You forgot one other "trick", and that is to used mixed graphics 
mode. That is to combine the 320 and 640 mode on the same screen, on 
a line by line basis (each scanline can be either in 320 resolution 
or 640 resolution, with the former of course being able to use 16 
pure colors with no restrictions).

    In fact, I believe that is what is used by the Star Trek stack
mentioned above. The areas where there is a scanned image is in the
320 mode (using 16 shades of grey) and the 80 columns text below it
is in the 640 mode using the "640 default" dithered color set. You
can split screen resolution much the way you can split areas of the
screen for color palettes. That is how there are near-photographic
quality images, with readable text and bits of color (which you'll
note are never in-line with the scanned photos).

Mitchell Spector
spec@vax2.concordia.ca