Siddiq wrote:
>is there any technical reason to prefer higher resolution scans if the end
>product is web-gallery use? 1800x1200 vs 3600x2400 roughly, say? the
>former resolution scans cost 3$/roll over and above developing at sams,
>the latter 9$/roll. it does give me more flexibility in cropping should
>that need arise, but anything else?
>
In theory, yes, although it depends on the implementation. This is an
exerpt from the instructions for VueScan, under the heading "Maximizing
Image Quality"
"Another useful way of getting multiple image samples is to scan at a
higher resolution and then average adjacent blocks of pixels. For
instance, scanning at 2700 dpi and averaging every 2x2 block of pixels
will result in a higher-quality 1350 dpi scan than just scanning at 1350
dpi. Scanning at 1350 dpi in this case will throw away every other pixel
and every other scan line, while scanning at 2700 dpi and setting
"Output|TIFF size reduction" to 2 will result in averaging 2x2 blocks of
pixels and increasing the number of effective bits of resolution by 2 bits."
There may be others who know more about scanning than Ed Hamrick, but
they aren't talking. Assuming that the pricing you quote is at least
partially related to the time it takes to do the scan, one might assume
that what he says is true for your vendor as well, since scanning at
higher resolution and downsizing would take longer.
>both are JPEG format (i KNOW i read that fuji frontier can output to lossless
>TIFF format on photo.net threads, but i guess it depend on how well the
>operator knows the machine, in my case they said they can do high res, not
>lossless).
>
You may not be asking the right question here. JPEG compression can be
lossless, very slightly lossy, but nonetheless quite high quality, or highly
compressed and pretty bad. The JPEG process allows a wide range of
quality/compression settings. You need to know what quality the scan outputs
are and what that means in terms of results.
Another issue is the other qualities of the scans. I was buying 2000x3000 pixel
lossless scans for some time and liked them quite a bit for various Supras and
the Portra NC films. I could use them for many web and small print uses. I also
had a 2720 dpi scanner to use with special and/or tricky images. Then I had
them scan and develop a roll of Portra VC. Way too contrasty, lost shadow
detail and blown highlights, useless. I asked and was told they did no
adjustments when scanning, what the machine (AGFA) does is what you get. Then I
got back a roll of Portra 160NC with some strange off colors on several images
and another roll just not right. I've given up now and just have the film
developed and cut into strips of 6 to fit the scanner.
I've now gone to a Can*n FS4000 scanner, partly for the greater resolution,
which doesn't make much if any difference for the web, and partly for the
ability to scan 6 negs or 4 slides at once witout having to click the holder
forward between frames. Lazy, I guess. :-)
Another issue with the scans you are buying is that they are 8 bit. That's fine
for most shots, IF they get the histogram right. If not, and for images with
very wide dynamic range, they are not going to give you what is in the film.
Also, for images that need considerable adjustment to brightness, color,
contrast and/or curves, the 8 bit dynamic range starts to get holes and bumps
that can make the image look "funny" in sometimes hard to describe ways.
Scanners with 12, 14, 16 bit depths don't have the same problem.
One possibiliity for you is to buy the cheap scans to use as indicators of what
is likely on the film and possibly for web use and an inexpensive scanner for
keepers and those that the cheap scans don't do justice to. That's what I was
doing with the FS2710. Another possibility is a cheap flatbed like the Epson
3170 for $124 refurbished from the Epson on-line store. Although it won't give
the same resolution as a 2700 dpi dedicated film scanner, it should be about as
good as $9/roll scans in real resolution and better in color and control over
the results. It also claims full 16 bit internal processing and output, but the
sensors don't really have that great a range. Much better than 8 bit anyway.
This is the scanner Richard L has been using for his lovely posts. For under
$200, the Epson 4180 should beat the $9 scans in all respects. The thing to
remember about flatbed scans of transparent sources is that they always need
sharpening in the scan software or afterwards. There
are long discussions around about this, but the bottom line is that's just the
way it is.
Moose
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