Message-Id: <mailto:199506081800.LAA10441@listserv.ccit.arizona.edu> Date: Thu, 8 Jun 1995 11:59:43 -0600 From: Lynn Lickteig <mailto:vrc@SPOT.COLORADO.EDU> Subject: Re: Scanning B&W photonegatives ? To: Multiple recipients of list IMAGELIB
>
>An acceptable viewing resolution is achieved by
>scanning at
This is in response to the request for clarification of information by
Peter J. Roberts:
The answer is that it depends, like everything else, exactly what you wish
to do with the scanned image (I'm not talking about printing versus viewing
but rather how much detail you want to have in the image). Since most
monitors only have a display resolution of 72 dpi, it would be a waste of
disk space to scan at 150 dpi if you only wanted to final image to be 4x5.
If you were to scan the image at 150 dpi, you would effectively (in the
realm of your monitor) have enough information to create an image that was
8.332x10.415 (2.083 x 4 and 5). However, if the image on the 4x5 negative
is very detailed, you may want to a larger image in order toview that
detail.
An easy way to determine this on an ad hoc basis would be to determine a
ceiling for your viewable dpi level, and as each image is scanned determine
at which resolution to save at. If you are scanning using a plug-in
attached to Photoshop this becomes very simple. When you initially scan
the image, Photoshop displays it in it's 'real' size (that is if you said
to scan it at a size of 4x5, it would be 4x5 on the screen). This is
achieved by shrinking the pixel size (4 and 5 x the scanning resolution
divided by 72 - the screens resolution) of the image, and photoshop will
display that ratio in the image title bar. Now all you have to do is use
the magnifying tool to determine what amount of detail the image needs, and
change the size using the 'Image Size' command. You will then have an scan
that has enough detail to display the amount of detail it contains, while
at the same time not going beyond a certain standard file size.
I hope this has helped and let me know if you want to know anything else.
Aaron Howell
Visual Resource Center
College of Architecture and Planning
University of Colorado
mailto:vrc@spot.colorado.edu