Date: Mon, 24 Mar 1997 01:32:11 GMT
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To: djgpp AT delorie DOT com
From: Paul Dixon <p DOT dixon AT ic DOT ac DOT uk>
Subject: Re: Ideas for truecolor Allegro
Cc: Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk>

As a prospective user of Allegro who has so far had to stick to GRX because
of the lack of hi-colour modes, can I put in my twopennorth :

Firstly, support for 15/16/24 bit RGB modes would be wonderful !

Secondly, my personal view would be that there is little need for 16 bit
that cannot be solved using 15 bit, and that as both 15 and 24 bit modes
have unused bits it makes sense to use these for transparency. Using a valid
'color' for transparency would be a pain.

Example - what about photographic images imported eg from video grabber ?
Must the user scan every frame to dither every [bright pink] (or whatever)
pixel to [not quite bright pink]? 

As to the comment about having to clear out these bits before passing to the
video hardware, surely if the transparency bit is set you WONT be passing
the colour to the video hardware anyway - so zeroing is not an issue!

So my suggestion would be

support 15 bit (5+5+5+1 spare) and 24 bit (8+8+8+8 spare), with transparency
in the top bit of each mode.

if needed support 16 bit but with reduced support for transparency features.

Thanks for listening ...

Paul

ps (In case you are interested) most of the programmes I write are for
clinical monitoring - my interest in video is for research into video
monitoring of sick infants!