Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!oliveb!pyramid!leadsv!laic!nova!darin
From: darin@nova.laic.uucp (Darin Johnson)
Newsgroups: comp.graphics
Subject: Re: the word "bitmap"
Message-ID: <400@laic.UUCP>
Date: 4 Jan 89 20:01:10 GMT
References: <8568@pasteur.Berkeley.EDU>
Sender: news@laic.UUCP
Reply-To: darin@nova.UUCP (Darin Johnson)
Organization: Lockheed AI Center, Menlo Park
Lines: 26

In article <8568@pasteur.Berkeley.EDU> ph@miro.Berkeley.EDU (Paul Heckbert) writes:
>I've been troubled lately to see people using the word "bitmap" to mean
>a grayscale or color image.  As long as I can remember, however, "bitmap"
>has meant a ONE BIT PER PIXEL, black and white image.
>
>Where is this new, (and I believe) incorrect usage coming from?

Since many grayscale and color "images" are created from layered
bitmaps.  If I have 8 bitmaps, and stick them into consecutive chunks
of memory, it is easier to call it a bitmap, than "some bitmaps".
(instead of a 1-to-1 mapping to real display elements, it is a 1-to-1
mapping to imaginary and layered display elements)

However, for some computers than don't use layered bitmaps to form
pictures (such as byte-per-pixel), the term bitmap is misleading.

On the whole though, I don't think it causes much confusion.  Especially
considering that "bitmap" has meant things other than images for as long
as I can remember - allocation maps for disks, etc.  I tend to think of
a bitmap as a collection (regular array - any dimension) of bits which
regulary map from the bits to something else - a display, disk blocks,
etc.  The word "bitmap" has probably been around longer than bitmap
displays.

Darin Johnson (leadsv!laic!darin@pyramid.pyramid.com)
	"You can't fight in here! This is the war room.."