I would like to know if it's safe to move photographs around from file to file on the computer without losing quality in subsequent prints?

Last year I was using a basic, automatic film camera and I used to have my films developed and put straight onto CD at ASDA Photoshop. One day I decided to gather together a collection of photos that I had uploaded to my computer from various original ASDA CDs and computer and internet files, onto one CD so that I could take them to ASDA and have them printed.

When I got the photos back, some were very blurred and some were cut off at the sides. The technician told me that this was because I had either cropped or altered them on the computer, or because I had moved them from the original CD to 'My Pictures' and/picasa and subsequently back onto another CD. She said that "every time you move the files around you lose pixels and therefore quality."

I know for a fact that some of the affected photos had not been cropped or altered at all, only moved from one file to another and then onto the final CD. The majority of the prints were fine, just some of them were affected. All had been moved from file to file at least once. I can understand how if you alter or crop a picture, it has to 'stretch to fit the space', but I just don't understand how pixels can be lost just by moving files around on the computer.

Was the ASDA technician talking rubbish - perhaps there was something wrong with the machine - or is there some truth in what she said? If there's truth in it, is this something that only happens with photographs taken with film or does the same apply for photos taken with a digital camera? Now I have my new digital camera, I'm loath to remove shots that I may want to have printed in the future from my memory card, until I know whether or not moving them is going to affect their quality.

Thanks for any clarification or explanation anyone can give. :)

If you save the files as JPEGs then yes, when you save them you lose some data, because JPEGs are what is called "lossy" compression, which means that some data is lost to save on file size.

However, you do not normally see visible degradation in quality unless either it's been saved in low quality JPEG (high compression) or it's been saved, loaded and resaved multiple times over and over.

Now, just COPYING the files (eg using file+copy file+paste in windows) from CD to computer and back again does NOT do any of that and shouldn't alter the file in any way. It's only if you load the files into an editing package and save them that you'd possibly get degradation.

(Windows rotate may alter them as well.)

Oh thank you so much for your helpful response. Now I just need to find out how to save files in something other than JPEG format.....please excuse my total ignorance on the subject, I'm a beginner!

There's nothing wrong with JPEG per se - that is the format that most (point-and-press) digital cameras use to store pictures.

The problem comes when/if you edit them and re-save, and keep doing so... then you would notice a drop in quality.


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There's nothing wrong with JPEG per se - that is the format that most (point-and-press) digital cameras use to store pictures.

The problem comes when/if you edit them and re-save, and keep doing so... then you would notice a drop in quality.


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Thanks, but would the problem also occur if you don't edit them, just resave them?

Also, with a digital camera, if you upload the contents of your memory card (SD or XD) to the computer, then move the files back onto the card, would degradation result then?

:)

...is this something that only happens with photographs taken with film or does the same apply for photos taken with a digital camera? Now I have my new digital camera, I'm loath to remove shots that I may want to have printed in the future from my memory card, until I know whether or not moving them is going to affect their quality...

So, I'm still unsure, does this degradation happen with photos taken on a digital camera as well as those taken with film? I presume it must, as JPEG seems to be 'it'.....? :)

So, I'm still unsure, does this degradation happen with photos taken on a digital camera as well as those taken with film? I presume it must, as JPEG seems to be 'it'.....? :)


It's to do with the files being repeatedly loaded and saved in JPEG format. Not really relevant what the original type of file was.


Thanks, but would the problem also occur if you don't edit them, just resave them?


Yes.




Also, with a digital camera, if you upload the contents of your memory card (SD or XD) to the computer, then move the files back onto the card, would degradation result then?


No, that's just moving files around.

What causes it is when you load the file, [optionally do stuff to it] then save it as a JPEG. But you'd have to do that a lot of times to see a change.

See this -

http://www.whatdigitalcamera.com/help/article.php?id=65942

and this -

http://graphicssoft.about.com/od/formatsjpeg/a/jpegmythsfacts.htm

:thumbsup: Thank you very much. Your posts so far have been very helpful. The links you suggested are also very helpful and clarify further. It's made me realise that there's so much to learn. The computer side of it seems more complicated to me than the camera side of it! Onwards and upwards...........! :)

To answer your point in post #3, it's best to save in a lossless format such as tiff or DNG until you're ready to print or put on the web.

If that sounds double dutch please say so and I'll try to find time to write a brief tutorial over the weekend.

"Workflow" is just as important as picture taking and processing if you want to produce good quality digital output.

It's the process of compressing into JPG format that gives the degradation - more compression gives smaller files but more degradation. If your camera can save RAW files, or TIFF (unlikely) or DNG then set it to do that, if not set the highest JPG quality you can - that will give the least compression and hence the least degradation.

When you're working on a pic in Photoshop, say, or Elements, then save in Photoshop's native PSD file format while you're working on it, that's lossless, and only save a copy in JPG format when you're ready to print. If you want to work on it again later then use the PSD file again not the JPG.

I tend to avoid jpg until the very last stage (as in, putting images on CDs to send to clients or uploading to be printed online).

Hard drive space is cheap, and processors are always getting more powerful, so saving as TIFF (big files, no drop in quality) is actually a pretty sensible way forward at the moment.

To answer your point in post #3, it's best to save in a lossless format such as tiff or DNG until you're ready to print or put on the web.

If that sounds double dutch please say so and I'll try to find time to write a brief tutorial over the weekend.

"Workflow" is just as important as picture taking and processing if you want to produce good quality digital output.

Yes, that sounds like Double Dutch! How on earth do I "save in a lossless format"??? I take the photos, they are stored on the memory card, the memory card goes into the side of the computer, the files are loaded onto Adobe and stored in 'my pictures', from there I upload them to PicasaWeb..............where do I get the option in that lot to save them in a lossless format? :help:

I tend to avoid jpg until the very last stage (as in, putting images on CDs to send to clients or uploading to be printed online).

Hard drive space is cheap, and processors are always getting more powerful, so saving as TIFF (big files, no drop in quality) is actually a pretty sensible way forward at the moment.

:huh:How do I know whether my files are "big files" or not, though? I'm at a total loss here! :help:

Don't know what software you're using but try saving as a JPEG at the highest quality you can and then at something much lower - eg Photoshop grade 12 and grade 3. You should be able to do the same thing directly on your camera by saving as high quality JPEGs and then as low quality. On a 6MPx camera you'll probably get files around 4-5MB in high quality but well less than 2MB in low. You'll almost certainly be able to see the difference in the pics.

Yes, that sounds like Double Dutch! How on earth do I "save in a lossless format"??? I take the photos, they are stored on the memory card, the memory card goes into the side of the computer, the files are loaded onto Adobe and stored in 'my pictures', from there I upload them to PicasaWeb..............where do I get the option in that lot to save them in a lossless format? :help:

I may have lost the thread here, but I thought we were talking about editing and saving. If you just upload your pics straight from the camera, then there's no need to do anything different.

If you do any editing, I would suggest :

1 - Copy all photos from the card to a folder called "jpgs"
2 - When you open a file and edit it, save it as a tiff in a folder called "tiffs".
3 - If you need to do further editing at a later stage, work on the tiff.
4 - If you want to edit from scratch, reopen the jpg, which will still be in the same state as when you copied it from your card, and go back to step 2.
5 - When you are happy with the picture, save it again as a jpg, but with a suffix (e.g. save photo001 as photo001a) and then put it on the web.

That way, your original photos stay untouched in case you need to start again, and all your edits and saves are done without losing image quality.

Yes, that sounds like Double Dutch! How on earth do I "save in a lossless format"??? I take the photos, they are stored on the memory card, the memory card goes into the side of the computer, the files are loaded onto Adobe and stored in 'my pictures', from there I upload them to PicasaWeb..............where do I get the option in that lot to save them in a lossless format? :help:

Sounds like you're not doing any work on the pics so why worry. If you are still worried then you really need to do a little research and learn about file formats and compression. It's as important as knowing about shutter speeds, apertures and focal lengths.

Sounds like you're not doing any work on the pics so why worry. If you are still worried then you really need to do a little research and learn about file formats and compression. It's as important as knowing about shutter speeds, apertures and focal lengths.

Yes, I gather that, as I said in a previous post, the computer side seems more complex to me than the camera side of it...........I think maybe I could do with going on a course, or something. Thanks. :)

I think maybe I could do with going on a course, or something.

Nah - experiment - play with JPGs, TIFFs, PSDs etc. See what happens when you open, fiddle and save multiple times. Google it, read about it... As a wise man once said, 2% of people can learn from others' mistakes, 3% can learn from books, and the other 95% have to **** on the electric fence for themselves!