I have seen conflicting statements about JPEG images. If I edit and save a copy of an image, does the original suffer any degradation? If so, then saving an original as a TIFF would make sense. Otherwise, I don't see the benefit of using the disk space on a TIFF image.Any help on this?

-- Lee Custer (phoebe@laguna.com.mx), April 18, 2000

Answers

yes saving a jpeg file back to the same format will always degrade it. depending on how much compression you apply the second time round, most people can get away with it once or twice without much noticible difference... but if you plan to work with it and need to have the best quality possible, then save it as a tiff or some lossless format and use that file instead...

-- Keat Lim (keatlim@my-deja.com), April 19, 2000.

If you edit the image and save it out as a new filename, the original image will not be degraded. If the original image came out of the camera as a jpeg, I would leave it archived as a jpeg. Moving the original to a tiff offers no advantage, and only results in a larger filesize. However, the NEW edited image you create should be saved out as a tiff if you desire to save the new file with no information loss.

I always keep my originals a jpg, just as they came out of the camera. Any changes I make, if I want to keep them, I will always save out to a new file. If I care about the fidelity of the changes (maybe to print it later) I will save it out as a tif. For web use, there is little choice but to save it back out as a new jpg. If I later want to make additional changes, I can edit the new tif with no further loss. For the jpg, I try to start again with the original and do it all in one shot if possible. That way I am only saving it out once.

-- Matt Magleby (mmagleby@neticus.com), April 19, 2000.

JPEG is what they call a "lossy" format, meaning it "throws away" information about the image. Each time you resave it, more info is lost. There is a program on the market put out by http://www.altamira-group.com called "Genuine Fractals". If you decide you're going to shoot only JPEG format, you might want to think about investing in this program. It allows you to save an image in a true lossless format, and later if you need to, you can pull the image back up, make changes, and save it as something else depending on your needs and the circumstances. BUT the original file as long as it was saved as lossless will ALWAYS remain lossless with this program.

-- Sue Bald (destiny3@ix.netcom.com), May 04, 2000.