FWD: Scaling gray-levels in mapraster.c

[teb]

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Date: Wed, 13 Sep 2000 14:58:10 -0400 (EDT)
From: Richard White <raw at essc.psu.edu>
To: mapserver-info at lists.gis.umn.edu
Subject: Scaling gray-levels in mapraster.c

All the drawXXX() functions in mapraster.c, when creating grey-level
color tables, appear to rescale the values to run from 0 to 16*17 =
272.  Can you tell me the reason why?

The question has arisen while I'm trying to write a drawBSQ() function
to incorporate support for aerial-photo type raster imagery into
Mapserver, with the images in binary band-sequential (BSQ) format.
Incidentally, since we want tiling, and the Arc/Info shape files aren't
really intended to work with raster images, I've defined a simple raster
tile specification file (giving filename, size, and extent of each tile
file) which I access via a reinterpretation of "tileindex" and
"tileitem" in the map file Layer object.

					Dick White

========================================================================
    Richard A. White
    EMS Environment Institute
    The Pennsylvania State University
    2217 Earth-Engineering Sciences Bldg.
    University Park, PA 16802-6813

    Tel. (814) 863-9540
========================================================================

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