From:	"Lionel Brits" <britsc AT cadvision DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: graphics question
Date:	Mon, 18 Jun 2001 12:55:48 -0600
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

Hi,

You have

const byte BIT[200] = {0, 0, 2, 3, 4, 6, 0, 0, ... }

If I understand you correctly, these numbers 0, 0, 2, 3, 4... are colours,
and don't represent 8 pixels as black or white bits. Now, images that are
stored as "bit maps" are just basic arrays of colours. They should actually
be called "byte maps", as most implimentations use one or more bytes per
pixel. The technical term is "raster image".

A program such as Microsoft Paint stores a 256-color image with resolution X
by Y as an array with X*Y elements. You can therefore read a .bmp file from
disk into an array and then display this array. The important part is
determining the characteristics of the image, which is stored in the file's
header.

You can find information on the .bmp format on www.wotsit.org.

Another format which is more commonly used is the targa .TGA format. It is
used because of its simplicity.

Finally, I don't think there is any sense in reinventing the wheel, though I
do recommend you try writing a program that displays a bmp file as an
execise. In the long run, it would be more effective to use a free library
such as OpenIL (www.openil.org / www.imagelib.org) since it is much more
powerful and will allow you time to work on other things.

HTH,

- Lionel Brits

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