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View Full Version : What do I do with existing JPEG photos?


Nick
23 November 2006, 11:47 AM
I read the thread "How much can I modify image master-files" with great interest.

I have over 400 photos in my Reunion file, all in .jpg format. I originally scanned them in this format, because I thought they should be in the most widely-used format, which seems to be .jpg.

The question is: Should I now change them to TIFF format, or leave them as they are? It is unlikely that I shall modify them in any way in the future - and I believe that they are only degraded when modified and saved.

Any advice would be gratefully received.

Gregg
23 November 2006, 02:05 PM
Should I now change them to TIFF format, or leave them as they are?I would leave them as JPEG since there is nothing to gain by changing them to TIFF and TIFF will take up a lot more space.

marnen
23 November 2006, 06:58 PM
It is unlikely that I shall modify them in any way in the future - and I believe that they are only degraded when modified and saved.
You are correct. If you're going to modify them, then convert them at that point, before you do any actual editing.

Carl and Ann Erickson
24 November 2006, 10:16 PM
I read the thread "How much can I modify image master-files" with great interest.

I have over 400 photos in my Reunion file, all in .jpg format. I originally scanned them in this format, because I thought they should be in the most widely-used format, which seems to be .jpg.

The question is: Should I now change them to TIFF format, or leave them as they are? It is unlikely that I shall modify them in any way in the future - and I believe that they are only degraded when modified and saved.

Any advice would be gratefully received.

Nick --
I would only convert the .jpg files to .tiff files if you are going to work on improving the images with something like Aperture, iPhoto, Photoshop, or Photoshop Elements. Converting the .jpg files will not be the same as photos taken in .tiff, which provides all new data in each file. The conversion process only duplicates the data already in the .jpg file making the file larger and that is only useful if you are going to significantly alter them to improve their condition as in repairing old photos.

Carl

AE Palmer
25 November 2006, 12:24 AM
You are correct. If you're going to modify them, then convert them at that point, before you do any actual editing.

Actually, you can edit jpgs and save them as often as necessary. Just do NOT save them with the same name as the original!! It is the act of writing a new file over the original that destroys the image quality. As long as the original is available, and identified as such, there is no danger involved.

That said however, the fact that jpgs are lossy, and human error commonplace, a single slip with the save command can and will degrade images.

As to your specific situation, I suggest that the images be burned on CDs. That way, there is no danger of losing the valuable original images.

marnen
25 November 2006, 04:42 AM
Actually, you can edit jpgs and save them as often as necessary. Just do NOT save them with the same name as the original!! It is the act of writing a new file over the original that destroys the image quality.
I don't believe that this is completely accurate. As far as I know, saving a JPEG image will always degrade the quality. However, you're right that if you change the name (or use a version-control system), you at least have the old version to go back to.

Michael Talibard
25 November 2006, 01:58 PM
[QUOTE=marnen]

marnen
25 November 2006, 07:03 PM
Technically this is so, but if we use jpegs sensibly, I don't think we should worry unduly. My image manipualtion software (called Photodesk) allows me to save images as jpegs with an 'Optimise' button ticked and with a variable quality, which I always leave at 90%. I don't have Photoshop, but I assume it offers similar facilities. With these settings, you get little or no visible deterioration.
That's true between one iteration and another, but if you make a lot of changes, saving your work as you go, then each save loses quality and you end up with an image that's much less good than it could be.
[quote]The uncompressed image was over 1700 megabytes; the jpeg, made as above, weighed in at around 180 megabytes

Michael Talibard
25 November 2006, 07:25 PM
Did you mean kilobytes? These numbers seem strangely large, unless you scanned at an insanely high resolution or the image was huge.
Very sorry

Michael Talibard
25 November 2006, 08:09 PM
OK, I've run the experiment again, modified as above. Had to start from a fresh scan of the same thing because I found I'd deleted it. This time my 90% quality jpeg was one seventeenth the size of the original. I made a small change each time, resaved under new name and quit the program. Perhaps my eyes are getting old, but I can't see any deterioration after ten such saves. If you'd like to see them, how do I send? Am I allowed to attach them to this? If so, how?

marnen
25 November 2006, 10:39 PM
You can attach files to your posts, but apparently not until you click the Edit button on an existing post. Or you can e-mail me directly at marnen@marnen.org if you'd rather.

Nick
26 November 2006, 05:53 PM
Very many thanks to everyone for your help. I think I'll maintain the photos in .jpg as suggested, since it's unlikely that I'll modify them in any way.

I also back up on to DVD quarterly and keep the DVD's for ever off-site, so I can always go back to dozens of old versions.

With many thanks again, to all.