I took the liberty to post Sean's instructions to this list, since his link
was flawed.
Robert Benschop
____________________________________________________________________________
1. Do not use JPEGs as your source file, unless they were compressed with a
very small amount of compression. As can be seen in (warning, bikini)
http://tokimi.collapsar.cx/avi/anime/aika.jpg, you can see the compression
artifacts along sharp changes from light to dark. Use GIFs or TIFF as your
source.
2. You need to find a better conversion algorithm from color/grayscale to
16 grays, one which uses error-diffusion rather than simple thresholding.
Compare the obvious threshold lines on (warning, nude)
http://tokimi.collapsar.cx/avi/adult/stapla.jpg with the error diffused
random dithering at (non-nude)
http://scruffy.cs.umd.edu:8080/seanl/Newton/Phantom/index.html
On the Newton the thresholding looks even more pronounced. If you have a
program which only lets you do thresholding, THROW IT AWAY. :-) It is a
very poor choice for Newton pictures! It makes a *world* of difference.
Anyway, I highly recommend GraphicConverter for the Macintosh (it's free).
To convert the image with proper diffusion in GraphicConverter, you do four
steps:
0. Uncheck "Dither" at
Picture:Colors:Dither
1. Convert the image to 8-bit grayscale by choosing
Picture:Colors:Grayscale:256 Grays
2. Then convert the image to 4-bit grayscale (16 grays) by choosing
Picture:Colors:Change to 16 Colors (4 Bit)
3. Save out your file as a PICT and convert it into a .pkg
following Avi's instructions.
[BTW, as a side note I've talked with Steve about the fact that Newt's Cape
only does thresholding in its picture conversions, but the person who did
the GIF/JPEG code is busy and can't add Floyd/Steinburg error diffisuion
right now].
Sean
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