Re: U.K. online BMD project collapses

In message of 20 Aug, Wes Groleau <groleau+news@xxxxxxxxxxxxx> wrote:

Tim Powys-Lybbe wrote:
Having said all that, it is remarkable to me how legible one-bit scans
can be if they are done at a high enough resolution. The preferred
resolution is usually 200 dots per inch but sometimes 300 is needed.

I prefer higher resolution in color. Since the original is generally
NOT grayscale (equal amounts of R, G, B on every pixel), having the
color info gives me more options in image processing.

one-bit is really unacceptable on most images I've dealt with.
one-bit makes stains either non-existent or completely black marks
with nothing you can do about it afterwards. And it completely removes
faded ink.

If I get a document in high-resolution 32-bit color, often with an
illegible original, I can use a decent interactive image-processing
program to make a very legible document in black & white.

I am talking about genealogy documents. Recently I had to prepare a
justification for some inheritance claim which involved some 144
documents for the family. I obtained certified copies from all the
right places. I wished to copy them and preserve the images on my
computer so that I could generate fresh copies whenever possible and,
indeed, send to anyone who was interested not to mention also putting
them on a web site.

So critical factors were those of space on the disc and speed of
transmission. This meant the file sizes had to be small. But
legibility had also to be maintained.

Some of the files I had to scan and store in greyscale as they were
indeed illegible in one-bit colour. But of the 144 documents I only had
to do this for ten of them. The average file sizes were:

Greyscale: 3.25 MBytes average over the 10 files

1-bit black & white: 72 KBytes average over the 134 files

In other words the 1 bit files saved 426 MBytes of storage space. Not
to be sneezed at!

--
Tim Powys-Lybbe                                          tim@xxxxxxxxx
             For a miscellany of bygones: http://powys.org/
.

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