I'm currently using a UMAX 300P that claims a
maximum 24 bit color
resolution of 300x600 dpi. I'm scanning into Photoshop4 and saving
in JPEG format. I'm trying to save as much information as I can, so
pages that have any color besides black and white, I'm scanning
at 299 (that's the max for color) dpi in RGB and and everything else in
299 dpi grayscale. I'm averaging, for 8.5 x 11 pages, about 5.3 Mb
for color and 2.1 Mb for grayscale. Just last weekend I burned
my first CD of docs consisting of 26 color pages and 170 B/W
pages for a total of 454 Mb.( I didn't fill the CD bcause I was anxious
to try printing the files at work.)
I printed two of the highest detailed B/W pages (schematics) today
at 400 dpi. The results were disappointing. All of the fine details were
lost. I assume I need to use a higher resolution for printing. I also have
quite a bit of background clutter on the printed page. I'm having no
problems seeing the smallest details when I magnify the pages in
There's not much point in printing at a higher resolution than the scan.
I'm not familiar with the Umax 300P. Is that 300x600 intrinsic resolution, or
interpolated? You almost certainly want any interpolation or dithering turned
off, because it will de-sharpen the image.
There's also not much point in using grayscale unless you're scanning photos;
if the text is B/W, scan in B/W. It saves a lot of memory/filespace, and has a
better chance of losing the background clutter. That's why photographers copy
documents with very high contrast "line" film, which basically comes out black
and white with no shades in between.
You'll probably want to retouch the images to get best results (obliterate any
remaining clutter, and/or fill in any missing pixels), and you may need to
adjust the scanner's contrast or intensity setting(s) to get best results. The
optimum settings will probably vary slightly between documents.
Also, don't use JPEG compression, unless you're only compressing by relatively
small amounts. JPEG is a lossy compression system; the compressed-and-then-
expanded image is not the same as the original; detail *is* lost. GIF or TIFF
All this is a bit general, but is based on my own experience. Once upon a time
I was a photographer (for a printing business) and I use a small desk scanner
myself, for faxes and assorted images. More often than not, I end up either
retouching the images, or rescanning with different settings, and quite often
pass them through image enhancement software afterwards.
Pete Peter Turnbull
Dept. of Computer Science
University of York