"G.R. Patterson III" wrote in message
...
Jpeg is the preferred format for photos that are going to be displayed for
view
(for example, the shots we submit to Jay of our aircraft should be jpegs).
Gifs
are preferred for shots that people are likly to just glance at (for
example,
thumbnails) because they typically are smaller than jpegs and consequently
load
faster.

IMHO, you have this exactly backwards.

Generally, a GIF (or PNG or compressed TIF, for that matter) file will be
larger than a JPEG file, for the same image. GIF is a non-lossy compression
format, and doesn't have the luxury that JPEG has of throwing information
away to make the file smaller.

In the case of computer-generated images or natural images that have few
variations (scanned B&W document that has been "posterized", for example),
GIF can come out ahead with a smaller size and more importantly, will not
lose any detail the way a JPEG will. But this is the exception to the rule,
and doesn't apply to photographic images.

Generally speaking, if you have a GIF image and a JPEG image the same size
(in pixels) and the GIF image is smaller, it's either because the JPEG
compression was set to the minimum value, or because the JPEG version has
24-bit color while the GIF has only 8-bit color (which obviously results in
a 2/3 reduction in file size even before any compression has taken place).
The color-depth difference is, in particular, a very common reason one might
be fooled into thinking JPEG is not as efficient as GIF, since when
compression a color photographic image, that difference will almost always
exist.

Pete