First off, apologies for the length of this post/reply.

It sounds like there are two issues that you are questioning: the actual jpeg
vs. tiff question (is one "really" better than the other) and the question of
economic benefit, by which you seem to mean both cost of equipment (storage
media, higher-power computers, etc.) and staff time and effort.

I think you are, in part, answering your own first question by repeatedly
invoking the phrase "indiscernible." "Indiscernible" is, you must admit, a
highly relative term. For example, it is true that on-screen, the human eye
will not be able to tell the difference between a jpeg and tiff image. This
is also true of images printed on low-res printers (such as the dye-
sublimation printer used in the Smithsonian AMNH test that you provided a
link to). But this would not be true of images printed on high-res printers
(1240-2480 dpi), as I can tell you from years of experience in working with
digital imagery for screen and print use. The common response to this is "but
we don't use anything that high-res, and don't plan to." But that is a
shortsighted view, as there is no way to predict what the march of Moore's
law will bring to computer technology.

For example, when my institution began scanning hundreds of images to prepare
for web use only two years ago, everything was scanned and stored as 300 dpi
tiffs, with the logic that since they were web-only and screen resolution is
72 ppi (Mac) and 96 ppi (Windows), this would cover all discernible future
uses on-screen. The predictable, of course, happened... increased bandwidth
begat increasingly complex technologies. When we designed our new website, we
decided to integrate FlashPix, which lets visitors zoom in on artworks at
very high magnification and pan across the surface. Great technology, works
even on a 28.8 modem, and requires... you guessed it, original images at (in
some cases) over 600 dpi to process into the necessary format! All those
scans had to be re-done, at great expense. (they also would have had to be
re-done had we saved them at 600 dpi originally, but as jpeg's, as zooming in
several hundred percent on a compressed image would have left us with very
poor image quality)

In short, if you are already going to the expense of undertaking a digital
imaging project, why would you NOT store originals in as high a quality, and
at as high a resolution format as is feasible? Part two of your question
seems to be financial... but I fail to see any great savings by compressing
images and tossing data. First, the cost of storage has dropped so low as to
be a non-factor. A 40.9 gig hard drive costs $299, and could store 1,500 28mb
images, about .19 cents each. A CD writer is $200, and blank discs less than
a dollar each, each of which can hold 23 28mb images, about .04 cents each.
Unless you are talking on a scale of millions of images, I don't see where
storage costs are an issue. Hardware, as well, isn't an issue. A brand-new
dual processor Macintosh G4 (the first "home" computer to be classified as a
supercomputer by the government, and hence face export controls for national
security purposes!) is about three thousand bucks, and processes huge files
instantaneously. Windows machines have similar powerful equivalents. It takes
no longer to scan, process, and save a tiff file than it does to scan,
process, convert, and save a jpeg. Where is the economic issue, assuming one
is writing a grant to undertake such a project?

Even if there is (for some reason I'm failing to see) a large enough short-
term economic benefit to saving jpeg's versus tiff files, you are gambling
that the money you are saving now won't cost you a whole lot more if you have
to repeat all the same work sometime (2, 5, 10, 20 years) down the road. You
are economically better off planning for unseen contingencies now, getting
(literally!) the best image quality for your money.

This is not to say there is no place for lossy compressed images; they have
their uses, and for some kinds of materials, or some kinds of projects, they
could be entirely appropriate. But you can ALWAYS make a jpeg later from a
tiff; but once you throw out that data during jpeg compression, you can't get
it back later if you discover some use for a higher-res image, or need a
detail blown up, or some new technology comes along.

Finally, in answer to your question as to whether selecting one or the other
might affect the decsion of funding organizations, I would say the answer is
probably yes. I know that as a grant reviewer for several agencies that fund
digital initiatives, I tend to downgrade applicants who are looking to do a
large project using compressed imagery. It just shows, in my opinion, a lack
of long-term perspective for the institution and implies that the money that
would be given might, in the end, be wasted (because they will have to apply
for another grant, 5 years down the road, to re-do all the work the first
grant funded!).

Again, apologies for the length of this post. I hope others will also post
their opinions, as I'm certainly interested in seeing what popular wisdom is
on this issue. I'm sure someone will find a flaw in my logic (such as it is!)
:-)

Dennis

Dennis Kois
Assistant Manager of Design
The Metropolitan Museum of Art
New York

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