Re: PHOTO-3D digest 1630

[P3D RJ Thorpe <thorpe@xxxxxxxx>]

Someone wrote:

> Question:  Has anyone ever made prints from Realist color-neg film?
> I need 4x5 or 5x7 prints for my flatbed scanner to get decent stereo 
> images for the Internet.

I don't understand why you need 4x5 or 5x7 prints, not that it hurts
if you do have them. Depending on your monitor and prefered screen
resolution, you probably are only viewing things on your screen at
about 100 dpi.

To find your actual dpi divide your screen resolution by the horizontal 
width of the entire image on your monitor. Examples from my 3 computers 
are:

14 inch monitor
   (9.8x7.6 image area), 640x480 resolution [640/9.8]=65 dpi
15 inch monitor 
   (10.5x8.1 image area), 1024x768 resolution [1024/10.5]=97 dpi
17 inch monitor 
   (12.0x9.1 image area), 1152x882 resolution [1152/12.0]=96 dpi

To get an actual size screen image for my 15 or 17 inch monitor I would 
scan at about 100dpi (96 or 97). If my scanner was set to 300 dpi I
would 
only need to have an original that was 1/3 the size (300dpi/100dpi;
scan/
display). At 400dpi you could scan a contact print of a 35mm frame and 
get the same quality as a 4x6 print scanned at 100dpi which is all you
need for fullsize screen display. If you scan a larger print at a higher
resolution, you will only get a larger screen image, not a sharper
picture.
Example: A standard Holmes card (3 1/2 x 7) scanned at 600 dpi and
displayed
on a monitor of 100 dpi resolution would yield an image that would be
21"x42". You would have to reduce the resolution to make it fit your
screen
which is the same thing as scanning at a lower resolution in the first
place.
Maybe it's even worse since the resolution has to be reduced by an
algorithm and compromises have to be made.

Most of the obsession with scanning resolution is an artifact of the
print
industry and does not apply to the internet. The net is a low-res
medium,
at least for now. Our problem is to send out small files so they
download
quickly. We recognise that looking at things on a computer monitor is
NOT
going to be as good as looking at a slide through a first-rate viewer.
I make sure that my pictures are no BIGGER than 625x340 pixels which is
a 
full frame display on a VGA monitor with Netscape maximized, the lowest 
common denominator . A standard Mac has even fewer pixels to work with. 
I also reduce my color depth to 256 colors (8 bit). 16 millions colors 
(24 bit or true-color) just triples the file size not counting header 
overhead. It adds very little additional quality and no increased
resolution.

-- 
RJ Thorpe
Cedar Rapids, IA
mailto:thorpe@xxxxxxxx
http://www.skep.com


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