Re: Digital Film backup
An image on a (home made) CD is a dye-based spiral photograph of a digital
encoding of the image. The photograph is not latent; the dye changes
state upon direct application of high-intensity light, so it doesn't need
to be developed. It also seems to stay that way, so it doesn't need to be
Because it's dye-based, it's probably a good idea to copy the image to new
media (i.e. make a new CD) every once in a while. Fortunately, the copy
will be exact, not suffering from generational degradation.
If we (as a species) can still decipher cuneiform now, we'll still be able
to decipher--with the help of a microscope--ISO9660 spiral pictures of
JPEGs for thousands of years into the future, barring intermittent erasure
of all human knowledge in nuclear (or what have you) armageddons. By
then, the majority of historical images, however filtered by various
"social importance" filters through the eons, will have been transferred
to new encodings and new media.
But, one could always store images in a less-intensive simple encoding
(say, a bit map), and hammer the data into titanium. That, along with a
Voyager-style line image of a prism and spectrum with marks for R, G, and
B, should allow the most primitive of species to recover a digitized
image. I doubt the colorguide picture would even be needed, given how
clever we are right now.
So the only issues seems to be the appreciation of the image without
decoding, and whether or not analog chemical images can ever be adequately
digitized, and what to do until then, if they can.