JPEGs

[dkabat]

DUMB question - Am in habit of making copy of JPGs to TIFs as soon as I get on machine.  Is there any reason to keep JPG once copied like this?

Thanks
Dan

[AlanDunne]

Well your jpeg is the original so there is some value in keeping it. If you copy EVERY jpg to a TIFF immediately, then perhaps you no longer need the jpeg. If the TIFF serves as your original, and all further edits as layered (i.e. the original is the Background) then maybe your TIFF master can be the only file you need.

Do you really need to convert every image to TIFF? Perhaps you should go through a ratings exercise and only convert those that warrant it. And only convert them to TIFF when you are going to do something contructive with them. Are you simply converting to TIFF, or as part of the batch conversion do you do any capture sharpening or some standard practice on all images?

If you follow this approach you will need to separate the jpeg originals from your TIFFs as dscribed in the DAM Book

Cheers ... Al

[dkabat]

All of these are old JPEGS (shoot all RAW now) and wanted to get them into a less volatile file format.  Nothing has been done with the TIFs and just using them for long-term archive format.  More concerned with keeping whatever pixels are left after opening and closing etc for years.

[AlanDunne]

Dan,

if I understand you correctly, then your motivation for converting all those files to TIFF is for long term archiving and you believe that the TIFF format will be supported longer than jpeg? I would be interested in hearing other opinions but I think both formats are well entrenched, and if anything, jpeg is more entrenched than tiff. There are an awful lot of jpeg images out there. So I cannot see the value in converting to tiff if that is your reason.

I am not sure what you mean by tiff being less volitile? Is that refering to the lossy compression of jpeg, then yes, I agree, but you claim that you are not making any adjustments to those old tiffs, just converting to them.

I pesonally keep all my originals in their original formal (NEF to DNG being the exception) and for the select images that go beyong the proofing stage to actually having a master file, then I make those masters in a layered tiff format.

If you're a belt and suspender type of guy, then I would keep the jpeg original as well as your tiff. If you want to save a little disk space, the you could forgo the jpeg and keep the "original" as a tiff background layer, never to be changed. Or you could adopt a practice of separating derivatives from originals, keeping all your jpeg originals and only select images taken into tiiff.

I am not sure any answer can be thought of as absolute truth.


Cheer ... Al

[dkabat]

Al, thanks a lot very your thoughts.  I will rethink my position.

Dan

[James Mulford]

DISCLAIMER: I'm not a image "expert" nor do I understand all the internal workings of compression algorythms, etc. but, at least from what I've researched and read from the experts, it seems that ANY conversion "risks" losing something. True, it would seem that going from JPG to TIFF is moving UP the quality ladder but personally I have done a number of tests on different sizes, resolutions, etc. and it does seem that when you go JPG to TIFF and then later save to something else, there IS some degradation. I guess it really boils down to "how good" an image you have to have and what uses you expect to give those images.

But having said all that, I've also seen very respectable Stock Agencies who store everything in high-res JPGS. For example, I believe not long ago I read on Alamy.com that, while they ask for high-res TIFF files for submission by photographers, they later convert them all into JPGs. I know of other large collections who have standardized on JPG mainly because it is only a "storage" file and will never be manipulated at the pixel level. As Alan says, an "original" is always an "original" so, if disk space isn't an issue, keep the "original" original, even if you convert them all to something more suitable for your daily workflow.

I'd also like to hear input from a color compression expert out there.

[peterkrogh]

I don't believe you risk anything in either converting to TIFF and archiving or just archiving the JPEGs, with the following caveats.

The TIFF files will be much larger, with no increase in quality.
The JPEG files are at risk for a small loss of quality if you open and resave the image.  Adding metadata will do no harm, nor will simply opening and closing them.
Peter