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raw2spec.txt
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==============================================================================
Raw2Spec Version 1.0 August 3rd, 1991
Robert Barnhardt (C) 1991 Brain~Waves Group
==============================================================================
Raw2Spec is Copyright 1991 by Robert Barnhardt. You may use and distribute
the program and its accompanying documentation, as long as they are retained
intact, unmodified, and unmolested.
General Information
""""""""""""""""""""
Raw2Spec is a post-processor for use with the QRT/ST ray tracing system. It
converts the RAW output of QRT/ST into Spectrum 512 format, for display on
any Atari ST system that can display Spectrum pictures (what a coincidence).
Raw2Spec works in any resolution; however, the Spectrum preview is obviously
not available in monochrome.
Raw2Spec Usage
"""""""""""""""
1. Render an image with QRT/ST.
2. Execute Raw2Spec from the Desktop.
3. Ignore the cheap alert box title screen.
4. Select a RAW file to convert (such as the one you just created).
5. Do you want dithering? Dithering involves using algorithms to render
the RAW file with more accuracy than normal. I suggest you try using
dithering, and if the results don't please you, try again with none.
6. If so, what sort? The selections, from least to most advanced, are
'Simple' (one pattern), '4 x 4' (a 4x4 ordered dither), and 'Error'
(error dispersion, with Floyd/Steinberg filter). A good idea is to
start with the most sophisticated, 'Error', and fall back to the
lesser methods if you are not pleased with the results.
7. Use register 15? Spectrum 512 uses register 15 as its current drawing
colour, and any images that you wish to load into Spectrum 512 can NOT
use register 15. However, if you're only going to be viewing the
pictures, there's no reason why you shouldn't use it (and gain a few
extra colours in your image).
8. The picture will now be converted, at a fairly fast rate (~ 30 seconds
for a full 320 x 200 image). If your image is greater than 320 x 200
in size, it will be cropped (not shrunk).
9. You will now get a preview of the picture (if you're not in monochrome).
Hit any key to exit the preview.
10. If you're not in monochrome, you'll be asked if you you wish to save
the picture. 'No' will take you back to the first file selector,
and 'Again' will take you back to the first 'Dithering?' alert box
(and will use the same input file).
11. If you selected 'Yes', you'll now specify where to save the Spectrum
picture (as an uncompressed SPU file). Swapping disks is kosher. If
you click on 'Cancel', you will be taken to the 'Save this picture?'
alert, even if you're in monochrome. After the file is saved, you
will be taken back to the initial file selector, where you may choose
another file to convert, or exit the program by clicking 'Cancel'.
Technical Notes
""""""""""""""""
o Raw2Spec was written in 100% assembly, with AssemPro from Abacus
Software.
o The input image is currently cropped (top left corner), if it is
larger than 320 x 200. If another version is released, it will
allow shrinking by pixel averaging as an option.
o Dithering is used to reduce the input file, one scanline at a time,
into the range of 512 colours. The colours are then sorted by
popularity (frequency of occurance), and added to the palette in the
order of most to least popular; if a colour cannot be added, the
closest match is calculated by finding the least square to each
available colour. Finally, the scanline is plotted (this could be
done while setting the palettes, but using a strict left to right
plot routine is faster in the long run).
o The converter doesn't save in SPS format because SPS doesn't allow
for the use of register 15. I'm not sure of SPC format yet. If ever
I release another version of Raw2Spec, it will be able to save in all
three (SPU, SPC, SPS) formats.
An Explanation (not An Apology)
""""""""""""""""""""""""""""""""
To those who have written to me in the past: I have not forgotten you.
I did, however, temporarily abandon you in favour of something that's
slightly more important to me - education. I had been spending a
totally ridiculous amount of time on this computer, and when the power
supply went, I had a wonderful excuse to get back to the school work
I'd been neglecting. I've just graduated grade 13, and will hopefully
be attending a university (a cheap one) in a year or so. In the mean-
time, I'll try to complete the projects that I said I'd do for you,
barring any further technical difficulties; I'm not spending another
dime on this antique.
{ The next week... For a good laugh, read the post-script to the QRT_ST
documentation. Next time, I'll remember to knock on wood. }
Bugs, Comments, Lawsuits
"""""""""""""""""""""""""
Get in touch. You can contact me on CompuServe at user # 73707,533
(I am not a number, I am a free man) or on GEnie as R.BARNHARDT1 (how
original). If you're one of the few living people able to communicate
by non-electronic means, write me at the following address:
Robert Barnhardt
869 Garrison Road
Fort Erie, Ontario
CANADA L2A 1N6