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Re: filmscanners: Hello



"Ken Durling" <kdurling@earthlink.net> wrote:
"At this point I mainly am striving to just get the absolute best quality
photo and then reproduction thereof that I can . . .

"Another question when working with large files like this is at what point
do you do most of your image adjustment?   Do you do all your color
balancing, sizing, and similar image property work on the .TIFF and then
compress and run sharpen on the jpeg?"


You've gotten good advice from a number of sources, and by the way, nice
photos!  My perspective and knowledge is from a commercial, offset printing
perspective, and I don't know much about photographic (ink-jet, etc.)
reproduction of digital files. My personal scanning experience is for
screen-display images on a cheap scanner (Minolta Dimage Scan Dual II).
However, here's what I think.

Scanning in 16-bit mode is a waste of time and space for photographic color
images destined for print. Dan Margulis, author of Professional Photoshop,
has a standing challenge for any color photographic image which can benefit
from 16-bit manipulation over 8-bit in any real-world scenario. See
http://www.ledet.com/margulis/ACT_postings/ACT-8-bit-16-bit.html . Grayscale
images may well benefit from 16-bit files if they must be heavily
manipulated, but color images don't.

Scan at the highest resolution your scanner supports.  Whether you save as
TIF's, PSD's, or JPG's depends on what you want to do with the file in the
future and how much disk space you want to allocate to each image.  The big
mistake you can make is to think that because JPEG is lossy, it damages
files because it discards data.  Everything we do to files discards date,
but the remaining data is more valuable than the original data. JPEG's value
comes from the fact that there is less of it, but what's left gives visually
indistinguishable images in files that are 5% the size of TIF's. The JPEG
compression method discards data that generally isn't valuable in exchange
for disk space that is. See http://vectorsite.tripod.com/ttdcmp2.html for a
good description of the theory behind JPEG compression.

The problems with JPEG's come when they don't have sufficient resolution to
display without showing compression artifacts. By scanning at high
resolutions you can minimize that possibility.

If I had really great "keeper" images that I wanted to archive, or if I had
commercial scans that had a significant value, or if I had images that I
though I might use for some unknown purpose in the future, I'd keep them as
compressed TIF's. I would not send a compressed TIF to someone else--I'd
uncompress it first. If I were doing image corrections to a file that I
thought I might need to re-do in the future, I'd do the corrections on
layers and save the file as a PSD. If I was satisfied with the corrections,
I'd flatten the file and save as a TIF or JPG.

If I had 1,000 images that I wanted to save, I'd rather have them on one or
two CD's as high-quality JPG's than spread out over 20 to 30 CD's as TIF's
or PSD's. Run some tests and see if you can see any difference in TIF's and
high-quality JPG's.

Preston Earle
PEarle@triad.rr.com
------------------------------
I have little use for a man who can't spell a word but one way.--Mark Twain




 




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