In the last installments of this series, I have discussed some of the relative merits for archival preservation of the various image file formats. If you review the rationale behind each of the image file formats, you will quickly eliminate all but three main contenders; TIFF, JPEG and RAW. Each of these three has positive and negative features. Ideally, you would want a file format that would be readable on any hardware, would have a file structure that allowed anyone with enough time to reconstruct the entire image file without loss of data. Let me give an analogous example using another type of media:
Not too long ago in world history, but a long time ago in computer history, one of the first few software applications for the new personal computers was word processing. Unfortunately, when the programmers set out to create a word processor, they did not contemplate that their file types would have to be compatible with any other word processing program or even a later development in the same program. Documents in many of the original file formats are now totally lost to us today because the programs and computers that created them are long gone. To get a small idea of the problem, open a word processing document in a program like OpenOffice. If you create a text file, you can save it in any of twenty-one different formats. The most persistent of all of these word processing formats is a simple text file. Theoretically, if you could get a text file from the old computer disk or hard drive, you could still read the file. But any of the old word processing documents such as MacWrite, or even more obscure, the Friden Flexowriter.
The same thing is happening with images. Proprietary image formats, unless updated periodically, are a closed book. A program like Photoshop CS5 will save image files in any of about twenty formats. But, some of the older formats, like PICT files, are no longer supported.
Ideally, you would want to preserve all of the data possible about an image in any form. But there are practical constraints. The size of the files is still an issue. I am currently using 8 GB CompactFlash cards and I fill them up regularly on a photo expedition. My external storage capacity has increased dramatically over the years and now, 2 Terabyte drives are less than $150. But even with this huge amount of storage considering that a single RAW file can be over 20MB in size. To give some perspective, my original hard drives, just a few years ago were 40MB drives. In today's world they would only hold two pictures! From another aspect, if your computer isn't extremely fast by today's fast standard, these large files will clog up your computer and take really long times to load and editing is pretty much out of the question.
So, why not take all photos in RAW if you have a fast computer and huge amounts of memory? Yes, that is one option, but you might have to spend a great deal of time and effort to understand and use what you get. Maybe TIFF is looking better all the time. Unfortunately, not all hardware devices allow you to make a choice. But if you have a choice, you might consider them in this order, RAW, Tiff and last but not necessarily bad, JPEG. I would stay away from most of the other formats for long term storage of valuable original photos.