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Re: Apple II Reference Manual Addendum PDF now online

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In article <avXve.78228$HI.71270@edtnps84>,
Craig Bower <to.email.me@post.a.request.message> wrote:
>If that one doesn't print out good and readable, perhaps you
>could toss a few pointers my way on scanning it in so it will
>work for you with your system.  I just tried a printing a test
>copy from the 300dpi scans, and so far (aside from dying ink
>carts) it looks pretty piss-poor when printed.
>
>What I'm doing now is using a Canon generic LiDE scanner
>with Paint Shop Pro 7.02, scanning at 300 dpi and then saving
>as a JPG with "1" for compression, meaning minimum
>compression.  Maybe there's something else I could do to
>improve the quality?

JPEG implies that you're saving grayscale (8 bpp) or color (24 bpp) data. 
You could get better print quality (and drastically reduce file size) by
converting to 1 bpp.  Here's what I would do with what you're trying to
scan:

1) Scan the source material at 600 dpi grayscale (8 bpp).  Save in a
   lossless format, such as PNG or TIFF.
2) Convert the grayscale data to 1 bpp, using thresholding instead of
   dithering.  Save to a lossless format (JPEG is useless at this bit
   depth).

Your scanner driver can probably do thresholding by itself, but I prefer to
do this in software.  You can scan once to grayscale, tweak the threshold
until you get it right, and then toss the grayscale files.  It saves a fair
bit of time, compared to scanning pages multiple times to get the results
you want.

I tried something similar with the images you provided:

for i in `seq 1 8`; do djpeg a2rma0$i.jpg | ppmtopgm | \
pgmtopbm -thresh -val .8 | pnmtopng -comp 9 >a2rma0$i.png; done

(-val .8 is the threshold below which grayscale values are converted to
black; values above that are converted to white.  You need to determine the
correct value through experimentation with your scanner and source
material.)

300 dpi is still not quite good enough for the schematics, but the pages
with text looked pretty good when I printed them.  While the JPEGs you
posted need about 7.8 MB of storage, the PNGs I created only took 315K. 
Concatenating the images and making a PDF of them with produced a 233K
file that you can download here:

http://alfter.us/files/a2rma.pdf

That's even smaller than the low-res PDF on your website.

  _/_
 / v \ Scott Alfter (remove the obvious to send mail)
(IIGS( http://alfter.us/            Top-posting!
 \_^_/ rm -rf /bin/laden            >What's the most annoying thing on Usenet?

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