Re: filmscanners: RE: filmscanners: Re: Hello, thanks, and more.

[Arthur Entlich <artistic@ampsc.com>]

As mentioned, the 72 dpi number is a bit long in the tooth these days.
It was a Mac standard used for screen fonts, but is no longer valid for
most monitors which use higher resolutions.  Larger monitors (17, 19, or
21") often function at 80-100 dpi or even slightly higher.

Now, 72 dpi (or even 100 dpi) for screen use is just fine.  Remember
that each screen pixel can be one of 16.8 million colors in 24 bit mode.
   Printed dots are another matter entirely, requiring 200-500 dpi, since
colors are produced from many dots, and also the resolution of paper
images is higher.  Screen images are quite forgiving.

It is true that a 72 dpi scan is likely not to look very good if scanned
at that resolution.

The way around this is to scan at a higher resolution (either the actual
full optical resolution of the scanner, or an evenly divisible
fraction).  So a 2700 dpi optical scanner should scan images at 2700
dpi, 1350 dpi, 900 dpi, 675 dpi, etc. 450 dpi, etc.

For best results, use 2700 dpi.  Then using a quality image manipulation
program, use their best downsampling method (bicubic is one) and have
the program reduce the dimension and resolution of the scan to whatever
dimensional size and dpi you think best for screen shots on the web
site.  Then sharpen the image with unsharp masking, to crisp up the
image, and then, finally, jpeg it to further reduce the file size.

Some film scanners come with good down and upsampling software, in which
case working in something like Photoshop isn't required.


Art

Ken Durling wrote:

 > On Mon, 22 Oct 2001 19:12:10 +1000, you wrote:
 >
 >
 >>If you're making web images, the dpi for the screen is 72dpi.  End of 
story.
 >>
 >
 >
 > Right, but scan at 72 dpi and you get crap.   One day I'll understand
 > all this.  ;-)
 >
 >
 >
 > Ken
 >
 > .
 >
 >