Degradation Image Quality: Move versus Copy

<p>Thanks so much for taking the time to answer this question! <br>

Is it better to "move" a jpeg file rather than "copy"? In general, I'm wondering if there is less image degradation when you use "move." <br>

Also, I just bought a new PC and am transferring all my photo files to the new PC via an external hard drive. I'm guessing that in this case there would be no difference at all between move and copy because I'm moving it to a different physical location. Any thoughts?</p>

<p>Thanks!</p>

<p> </p>

<p>Doesn't matter. And it doesn't matter that it's a different location either -- "move" is just "copy + delete". Either way, you're just copying the bytes from one to the other, there is no degradation. The degradation happens when you reprocess the image, because it goes through another JPEG compression phase.</p>

<p>Copy vs. move. No difference, it's all digital -- the operating system makes an exact copy of the original file regardless if you move it or copy it. Don't listen to anyone who tells you otherwise. When you copy or move a file to another location (another folder, another disk drive, to a USB dongle) the O.S. does not care what kind of file you are copying.</p>

<p>Zero pct. chance of image degradation -- that only happens if poor (non existent) workflow is followed when EDITING image files in your photo editing program.</p>

Actually, if you move a file to another location on the same disk, you don't move, change, or rewrite any data. The file stays in exactly the same place on the drive and is not changed at all. You just list it in a different folder.

 

But even if you move it to another disk drive or if you use copy and paste to

copy it, there is no degradation of quality. Every byte of information in the file is copied exactly.

 

Image degradation happens ONLY when you Open and Resave a jpg file.

<p>As the others have stated, move and copy are identical in that they copy the data precisely.</p>

<p>However, I am careful when using "move" from one device to another. If I don't have another copy of the files, I will copy, verify that the data are copied, then delete from the source. I have had move operations crash and corrupt data. Admittedly, this is rare, and it hasn't happened to me in a long while. But better safe than sorry.</p>

<p>Dan, interesting. I think I sort-of knew that at some time, but kinda forgot. All just shuffling in the File Allocation Table.</p>

<p>To the OP: I liken digital info to music: the code for (say) a Bach composition is the same now, note-for-note, as it was the day it was written.</p>

Charles, yes, that is the best approach. Verify the new file on the second disk before removing the original. The target

disk could be full (not enough space for your file) or the cabling could come loose or power could falter during the copy.

Unless you are copying files with some mechanism that does error checking for you (such as a backup utility), you need to verify the

copy before you delete the original.

 

Mendel, that's correct. Unless you use a cut and paste method to move the file to a new location on the same disk, the

contents don't move. The file's identifying handle is just moved from one folder to another.

 

Copying a jpeg works just like copying a spreadsheet or a Word file. Words and numbers in the file don't change when you make a copy. The copy is exact. The content is not altered. The degradation of a jpeg file comes when you edit the file and save it again, because compression applied every time you save it. To use your music analogy, imagine converting a song on a CD to an mp3 file. Then

convert the mp3 to a wav file. Then convert the wav file back into an mp3 file. Every time you do the mp3 conversion some resolution will be lost.

<p>An interesting article in a fairly recent issue of the British mag, "B&W Photography", where, in comparing RAW vs. JPEG, the author found that recopying a JPEG image a number of times in highest quality setting yielded little or no perceivable deterioration, whereas using a lower quality setting introduced definite degradation after only a few times of recopying the file. </p>

<p>Arthur -- I hope you mean "resaving" and not recopying. Copying image files always is zero degradation. Always. Without fail. <br>

<br />Saving is not copying. Don't confuse the issue in this basic forum. It's a well know mathematical fact that saving or re-saving a JPG image file causes loss of information of the original image. It's not debatable.</p>

<p>As somebody who has used digital for awhile ; all I can say is there exceptions too.</p>

<p>Here/Calif I have found that my Quebec customers files all worked and printed out OK when they were received via email and saved on the original drive; and printed from that machine. Later when they were moved on the LAN to my backup area; some of his stuff would not print; or had weirdness; ie lock the printer or RIP box. His file names were super long; with diacritical marks; underscores; and umlonts. Even when I renamed the ill files on the backup machine they had issues. Thus I found the original email from 8 months ago and resaved them on the mail server; then renamed them without diacritcal/umlonts and they now work on every machine.</p>

<p>If one goes back to older operating systems; the "chances" of having a super long file name; or a mess of nested subdirectorys getting "hosed up" goes up radically. Thus ones stuff should be checked; ie the stuff at the far end of the tree limb might be missing</p>

<blockquote>

<p>Thanks so much for taking the time to answer this question! <br /> Is it better to "move" a jpeg file rather than "copy"? In general, I'm wondering if there is less image degradation when you use "move." <br /> Also, I just bought a new PC and am transferring all my photo files to the new PC via an external hard drive. I'm guessing that in this case there would be no difference at all between move and copy because I'm moving it to a different physical location. Any thoughts?<br>

Thanks!</p>

</blockquote>

<p>As long as you're talking about moving or copying from within your OS (Windows/Mac/Linux - doesn't matter), there won't be a difference. The OS will do a bit-for-bit copy, and if you select "move" will then delete the original.</p>

<p>What you want to avoid is opening the files in an image editor, and then saving them (or doing "Save As...") to the new drive. This may cause JPEG images to be resampled, and can degrade their quality, if you're not careful.</p>

<p>Personally, I'd copy them, not move them to the "transport" drive. Better to have them in two (or more!) places!</p>

 

<p>Think of how computers work; if any bit of your data changed moving or copying files from drive to drive, or drive to RAM and back, software would neither install correctly nor would it work very well once installed... Great care is taken to ensure bit for bit accuracy in copy / move operations by your disk operating subsystem.</p>