digital news photos

[Paul Schliesser <paulsc@eos.net>]

>Okay- I stand corrected! I get confused easily! I thought that the price was
>a tad high, even if some company had to pick it up. Then too, if you are a
>photojournalist, does one REALLY need that high of a resolution to reproduce
>in a newspaper or magazine? I was under the impression that those plates
>rarely do better than about 150 DPI.

To do a full-page, full-bleed photo, with good quality, the original file 
needs to be about 2500 x 3600 pixels (about 9 million pixels). Normal 
magazine offset printing is usually 133 or 150 lines per inch (lpi), but 
it's normal to use 1.5 or 2 times that (in pixels-per-inch), so that more 
than one pixel is used to make each halftone dot. If you don't keep the 
number of pixels per inch higher than the lpi of the halftone screen, you 
can start to "see" the pixels in the printed image. This leads to digital 
artifacts, like jaggedness on diagonal edges, becoming visible. Most 
digital cameras use JPEG compression, which tends to make these artifacts 
very noticable, and further limits the largest acceptable size at which 
they can be used.

Newspapers let you get away with more, since they are generally printed 
at 100 lpi or less.

You can, of course, make a digital image any size you want, but the 
quality will go down quickly if you enlarge it too much. You might be 
able to make it look acceptable, but you can never add in information 
that the camera was not able to record.

One thing to keep in mind is that when you double the resolution, you 
quadruple the number of pixels in the file (2x width x 2x height), so to 
use the image at larger sizes, the number of pixels that the camera needs 
to capture goes up quickly.

- - Paul