My answer to this is simple to state, complex to describe. In writing
you write to the desired audience. In scanning or digital picture
taking you do the same. Scan for for the specific use. Here's some
examples.
If you are scanning a 4"x3" photo for screen backgrounds on a 1024x768
screen you want to scan such that the scan produces the eact output
you want. That means as close to (1024dots/4in) 256dpi as you can get.
If you are expecting to print out the image on 11"x8.5" paper on a
720dpi Inkject printer you want an image that is scanned to yeild that
resolution (if you have enough resources, and want the best results).
That is 11in * 720dpi = 7920 pixel wide image. Given the same 4"x3"
source you want to scan at 7920 pixels / 4" = 1980dpi. Or something
close to that.
If you're scanning images for icons on a web page you wouldn't want to
scan that high since nobody wants an icon that fills multiple screens.
You'll find that most digital cameras that are reasonably priced don't
really do resolutions high enough to get perfect quality 8.5"x11"
printouts. If the camera doesn't capture enough info you must either
print smaller pictures, do fancy processing to smooth the image, or
live with the blocky printouts. It is also a matter of space trade
offs, to high a resolution and you have a camera that only holds a few
pictures. Even if you found a camera that could scan at 8000x6000
(the 720dpi printer example above) you still wouldn't want to use it
all the time, since at even 16bit color that's 91MB per uncompressed
image.
>Sorry, this is off topic, but I know that only extremely intelligent
>people use Linux so someone will probably know the answers ;-)
>
>Could someone please clarify resolutions. I have a scanner and a
>digital camera (and of course a regular camera). Now 300DPI is pretty
>self explanatory. My digital camera is something like 1280x1024.
>That's fine but lacking a measurement it's meaningless. What is the
>equivalent DPI measurement? If that's for a 1" picture it's great but
>if it's for and 8x10 it's not so good. Is it standardized and if so
>what is the default picture size (which of course would yield the DPI as
>well).
>
>Now for the really tough question. What is the approximate resolution
>of a standard photograph?
>
>I want this to scan photographs. It seems that 300DPI is a good bet,
>any comments? My scanner/scanning program saves in TIF by default.
>I'll probably convert to JPG. My JPG converter has a 0-100% scale for
>"losiness" (new word I just made up, means the amount of loss ;-) )
>I've found that 100% (no loss) is a waste since the file size is about
>the same as the source file. Between 80% and 90% is good. I personally
>can't see the difference but there is significant file size reduction.
>Much below 70% and I can begin to see the loss.
>
>Thanks for any feedback. GGK
--------------------------------------------------------------
Robert E. Anderson email: [EMAIL PROTECTED]
Systems Programmer phone: (603) 862-3489
UNH Research Computing Center fax: (603) 862-1761
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