On 7/12/26 20:46, Joshua O'Keefe wrote:
On Jul 12, 2026, at 8:52 AM, Joshua O'Keefe
<[email protected]> wrote:
It resulted in a file under a meg.
Correction: "under a *gig*"
My apologies to the list for continuing to reply to myself but it might
be helpful to post my first pass at making the file a little more
manageable: https://archive.org/details/trs-80-model-100-portable-
computer-ocr-compressed <https://archive.org/details/trs-80-model-100-
portable-computer-ocr-compressed>
If anyone finds issues, I'd love to hear about it.
That is a great looking copy, still looks perfect while being half the size.
I Did manage to make a 60M version by just manually doing a lot.
I wouldn't normally want to degrade it so much but I wanted to include
it in my m100_dev repo, and github sets a filesize limit of 100M.
At 600 dpi, it's actually not too bad to jack the contrast to 100 to get
ersatz 1bpp. It's sharp enough to reproduce the newsprint dither dots in
all the diagrams.
All in all I did:
- saved the front & back covers separately as color jpeg, 80 quality I
think, 600dpi.
- cropped all the interior pages to remove all page edges and the spiral
holes.
- removed the blank pages
- Set contrast 100% and brightness 50% for most pages, making most pages
essentially 1bpp though not literally 1bpp.
- Some pages where some thin line or not fully black features
disappeared, reduced the brightness to 48 or 45 or however far ittook to
get the faint feature to appear
- Some pages where the brightness had to go so low it made other things
get larger and blob together or made a lot of junk appear in background,
reduced the contrast to allow a few levels of gray just for a few real
problem pages. With the brightness back up so that the background still
ended up clean white.
- Interior pages compressed with LZW.
Grayscale, 600dpi, lossless, but with most pages at 100% contrast the
compression gets rid of a lot of filesize.
- Combined the separate covers and interior files into a single pdf
without reencoding.
https://github.com/bkw777/m100_dev/blob/main/platforms/100/TRS-80_Model_100_Portable_Computer.pdf
There weren't too many problem pages in this book honestly.
One of the characterset glyphs is a circle drawn with a very thin line
and not even 100% black. pg 207/214 chr 166
By the time you reduce the brightness enough for that circle to appear
clearly, the rest of the page is too bold and things are blobbing
together. I think this is one page where I also dropped the contrast
down to 90 or 80, as the only way to avoid making everything else too bold.
On that same page also chrs 151 and 176 are a little flawed.
pg 205/212 the @ glyph is missing half of the outer circle, and by the
time you decrease the brightness enough to get that line to fill in,
other parts of the same page get too bold. The SHIFT & CAPS LOCK
graphics on the bottom of the page blob together and merge with the oval
outline around them. Still legible just ugly.
pg 203/210 the half-tone grid lines are tricky to get to appear clearly
without simply being full low-contrast grayscale.
pg 10/6 the diagonal line in the % on the keyboard.
pg 12/8 the text on the stickers.
Randomly some pages with the grey dither dots needed higher or lower
brightness than others. Either the dither dots were too faint or too
dark. Small changes in the brightness (with contrast still at 100)
affect the dither dots a lot without really affecting the rest of the
text too much. All pages were able to be made good but no single setting
is good for all pages.
--
bkw
