I shoot almost all my photos in RAW format, which means that my important originals are in a variety of different formats: some Nikon, some Canon, some Panasonic. All of these are proprietary formats (though they’ve generally been reverse-engineered), and so not really ideal for long-term archiving.
It was for this reason that Adobe, some time ago, came up with the DNG — Digital Negative — format: an open standard intended for things like archiving. There are tools for converting most things into DNG, and the idea is that you’ll always be able to get your images out. Some cameras even save DNG as their native format. It’s a very good idea.
The problem is that almost none of the tools I use support it. Adobe Lightroom does, of course, and makes it nice and easy to convert images automatically as you import them from your camera. But, once I have my image as a DNG, I find I can’t open it in Aperture, Preview, Acorn or even Photoshop CS3. I don’t get thumbnails in the Finder. I tried reverting to earlier, less efficient versions of the DNG format with fewer fancy options but it still didn’t help, unless you go back to really early variants, which can multiply the file size by three.
I could, of course, view my DNG files in Photoshop if I adopted the standard Adobe solution: pay hundreds of pounds to upgrade a product I paid hundreds of pounds for a little while ago. But I have the latest versions of other software products and none of them can open recent DNGs. Some of it may boil down to insufficient support in Apple’s underlying libraries. Whatever the reason, everything can open the closed, proprietary formats, whereas even Adobe’s DNG Converter can only convert to other forms of DNG. A few special tools like RPP can convert them to TIFFs, as long as you’re not using the latest DNG variants.
I’ve written about this before, but I repeat the experiment periodically to see if things have improved, because I really like the idea of storing things in an open raw format. But, sadly, at present, putting your files into DNG seems to imply locking yourself into expensive Adobe upgrades.