Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!dewey.soe.berkeley.edu!oster
From: oster@dewey.soe.berkeley.edu (David Phillip Oster)
Newsgroups: comp.sys.mac.programmer
Subject: Re: 32-Bit Color QuickDraw
Message-ID: <29861@ucbvax.BERKELEY.EDU>
Date: 28 Jun 89 05:50:08 GMT
References: <2497@quanta.eng.ohio-state.edu>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster)
Organization: School of Education, UC-Berkeley
Lines: 17

In article <2497@quanta.eng.ohio-state.edu> CURRAN@rcgl1.eng.ohio-state.edu (Curran, Jim) writes:
>	I was wondering if the 32-Bit QD extensions allow me to copy
>a 24-bit planar image (8 bits of red, 8 bits of blue, 8 bits of green)
>into an 8 bit pixmap using the CopyBits call. 

1.) you can't get a 24-bit planar image (8 red, 8 green, 8 blue) you must
use 32-bits per pixel to hold 24-bit data. (although, there is a new PICT
opCode that suppresses the extra byte.)

2.) there is a new CopyBits() transfer mode that, if the destination is
thinner than the source, CopyBits() uses dithering to approximate the
colors. The dithering algorithm is vaguely similar to Floyd-Steinberg,
but it only pushes error terms along the scan-line for speed.
 This works, even if the destination is an SE/30, so you can at least
do someting with color picts on a black & white mac.

All in all, it is pretty neat.