Jpeg to tif back-up

[Fastmarc]

A question to the knowlegable.
I have been downloading my jpeg images from my camera to an external hard drive, but backing it up by coping from this external drive to another drive. From my reading I realized that copying these jpegs onto another drive would resulted in the copies degrading a bit in the process.
Since then, I started downlaoding from the camera straight to the back-up drive, so essetially the back-ups are original too.
Now what to do about the images I had before I started doing this. The thought crossed my mind that I could create good back-ups by converting to tif (or even psd though that file file would be too big) and saving it to my back-up drive. This way the back-up copies wouldn't be degraded in the process.
Would this be right?

 

[deco_martini]

From my reading I realized that copying these jpegs onto another drive would resulted in the copies degrading a bit in the process.

Computer files are made of zeroes and ones. 00011010101

When you copy a file from one drive to another, it copies the zeroes and ones.

Your files do not degrade from copy operations. Opening the jpeg with an image program and saving it with lower quality settings is the only way to degrade the file.

 

[maged_mmh]

never heard about that "degradation" before

 

[bleeb]

Maybe confusing the concept of copying and pasting within an image editing programs (which often looses data and degrades the child image) and copying files from one directory or drive to another (which doesn't). The use of the same word to represent what are two subtly different operations could be confusing.

PS. Hard core geeks could get into discussions about bit error rates of data transfers or magnetic stability vs. time, but those types of errors don't generally happen often enough for the average user to notice (i.e. one error per billion bits or less).

 

[deco_martini]

PS. Hard core geeks could get into discussions about bit error rates of data transfers or magnetic stability vs. time, but those types of errors don't generally happen often enough for the average user to notice (i.e. one error per billion bits or less).

Hard core geeks checksum the file after the copy operation to verify its integrity. Of course, an error transmitting or storing the data isn't the same as it degrading from further color dithering or compression blocking.

 

[bleeb]

Hard core geeks checksum the file after the copy operation to verify its integrity. Of course, an error transmitting or storing the data isn't the same as it degrading from further color dithering or compression blocking.

Yahbut don't forget there's also the gradual demagnetization of the stored bits. (Or thermochemical changes if you're talking CDs or DVDs.)

 

[Warmwater Wank]

When you edit a jpeg (ie: when you make ANY changes) then save it as a jpeg you lose some quality. Why? Jpegs compress and get rid of information when you make editing changes (even a single tiny tweak). Since the original jpeg shots have already been compressed, even at the highest quality settings on your camera, why lose more information? It's why editing a jpeg, then saving as a jpeg is not a good idea. Edit a jpeg file enough times and you will degrade the image. (Just opening and closing a jpeg won't do this, but any editing will.)

Tiffs offer a no-compression option (if you were using Photoshop you are given that choice when you do a "save as"). Select "None" and what you have is what you save, w/ no loss, no compression. For your question, a lot could depend on how you are transferring your files to your external drive. Just transferring the data should not be a problem--in most cases. But say you had a file open in P'shop and decided to duplicate the file and save as a jpeg. P'shop would ask under "Image Options" if you want a small or big file and give you a slider to adjust. Even a "big file" ("maximum quality") would cost you information because yup, it is going to compress the info.

Run a test, see what you think. I don't see that just copying to jpeg is a problem but...if you are copying to a backup extenal hard drive why bother w/ jpegs anymore? File size would then be irrelevant, since you aren't limited by the size of your camera's flash card anymore. If you can, I'd say save your camera originals as tiff backups and work from your backups when editing. There are other ways to do this of course (Adobe's Lightroom offers real slick ways to handle this sort of operation) but before you get too concerned, open a file from your camera original and the same one copied to your external drive and do a side by side comparison at high magnification. If you notice any unacceptable loss then I'd look into making changes on how you save the backups and get away from jpegs.

A lot depends on what you shoot and what you want to do w/ the results. A pro trying to get something published has sunk a lot of serious money and time into getting the highest quality they can get--and they want to keep it all. (It's why they prefer RAW files, way more data is saved and never compressed.) Us mere mortals may not have quite the same issues but still, why lose anything if you don't have to? Hope this helps, sorry about the length of this post. // ww

 

[Fastmarc]

Thanks all. Your replies are really helpful.
So from what I am seeing, copying my originals to another drive won't degrade them. It is only the act of re-compressing them that will.
My camera only shoots jpegs and using the import funtion in Bridge (CS3) doesn't give give me the option to convert the images to tif. Once imported to the drive, I can open with RAW and convert to tiff though, but that will be double time.

 

[deco_martini]

Thanks all. Your replies are really helpful.
So from what I am seeing, copying my originals to another drive won't degrade them. It is only the act of re-compressing them that will.
My camera only shoots jpegs and using the import funtion in Bridge (CS3) doesn't give give me the option to convert the images to tif. Once imported to the drive, I can open with RAW and convert to tiff though, but that will be double time.

jpeg supports many lossless operations on photos as well. You can rotate, flip, crop, etc without losing quality. Unless you want to do actual editing with filters and gamma/correction, you can opt to not transform the pictures.

You image editor will usually convert the jpeg/tiff/gif/png when you open it into a plain bitmap in memory for editing operations, so you can edit the image that was in the jpeg and save the final image to whatever format you choose without losing any quality.

 

[Fastmarc]

Ok, just for clarification...
Originally after taking images, I would download from the camera to my storage device and maybe once or twice a month I would copy these images (drag & drop) from my storage device to another hard drive as a back-up copy. Based on my what is said here, this is ok. My images will be ok no matter how many time I copy them?
If this is so, then the act of copying straight from the camera to the 'back-up' drive is not necessary then.