On Fri, Jul 26, 2002, Gerald Oskoboiny wrote:
> This site:
>
>     Max Lyons Digital Image Gallery
>     http://www.tawbaware.com/maxlyons/index.html
>
> has some amazing pictures that were made by taking a bunch of pics
> and stitching them together, similar to the panoramic stitching stuff
> included with most modern digital cameras but with an improved
> process and tools.

He says he was using panorama factory[1] (indeed shareware) but he switched
to panotools, which is available on many platforms. However, panotools
is everything but easy to use. An easy tool for whom wants to try
stitching would be Canon's photostitch (bundled with -almost?- every
consumer digital camera from Canon). Other tools here:
http://www.panoguide.com/software/

In my opinion, the most useful use of image blending is not panorama
stitching, but blending to improve the dynamic range[2]. Slides are
known to have a small dynamic range (Density ~3.2 IIRC), inferior to
that of negative film. What is little known is that the sensors in
digital cameras (especially consumer cameras) have an even lesser
dynamic range.

Because of that, the usual trick (basically, underexpose and
post-process, since you can recover underexposed areas but can't recover
blown-up ones) is sometimes not enough to portrait a high-contrast
scene, and this technique comes in handy, and is quite easy to perform
(provided you have a tripod and a camera with manual exposure setting).

Tutorial:
http://www.luminous-landscape.com/tutorials/blended_exposures.shtml
Another example:
http://www.fredmiranda.com/article_2/index.html

Note that these tutorials only show horizontal blending, but (since
software like the gimp are not too bad at oblique gradients, and,
generally speaking, and layer manipulation in general) nothing
stops you from doing more complicated stuff. Kind of a digital "zone
system"[3] in some sense :).

If you feel this is "cheating", you've never seen what they do in "real"
darkrooms. That reminds me of a book where the photographer explains
how to use cardboard and scissors to make miniatures, cover part of the
print with the miniature's (or, sometimes, his hands/fingers) shadow, and
thus blend multiple exposures on a single print...
I'm not good with scissors, I prefer The Gimp. ;)


[1] http://www.panoramafactory.com/download.html
[2] http://www.dpreview.com/learn/Glossary/Digital_Imaging/Dynamic_Range_01.htm
[3] Ask google.

--
Olivier
http://yoda.zoy.org