Does changing the name of a JPEG file really cause loss of quality?

<p>I've been searching around online for a few answers to some questions I have with no luck so I thought I might as well sign up to photo.net and ask a few photographers.<br />1. Is it true that just changing the name of a JPEG file will cause loss of quality? Can someone explain this?<br />2. If someone sends me JPEG files through gmail and I right click and click "Save Image As..." and it asks me to rename it will those files lose quality?<br />3. If I made a copy of a JPEG file in Photoshop CS5 and renamed that copy will that copy still be an exact copy of the original or would it have lost quality because I made a copy of it and renamed it?<br />These are just some questions I cannot seem to find the answers to, thank you.</p>

1. No;

2. No;

3. I don't know.

<p>Can you explain this? Because i've had photographers tell me that renaming a file can cause loss of quality.</p>

<p>Renaming a file in the operating system does not change the contents of the file (it's not like your Word documents or spreadsheets get corrupted when you rename those files). <br /><br />For (3), I think it depends on whether you save the copied file at the maximum resolution or not. I use PS but I hesitate to say more than this.</p>

<p>3. It should be exactly the same if you <strong>didn't</strong> save it back as a JPEG again but rather a TIFF but it will be larger on disk. The saving <strong>as</strong> JPEG is what alter's the data (compression). But here's a way you can test it yourself, directly within Photoshop:<br>

http://digitaldog.net/files/Apply_Image.pdf</p>

<p>JPEG / Joint Photographic Experts Group ... The jpg format was hatched up back during the days when a 40 megabyte hard drive was the king of the hill. In a nutshell, when you save a file as a jpg, the format selects and deletes similar bits of information which will leave the recognizable image, but a much smaller size. That's the good news. The bad news is every time you save it, it recompresses meaning that it destroys more information, never to be recovered. If you must use jpgs, the best practice is to save the file in a non-destructive format such as tiff, psd (if you have photoshop), or bmp. Then work on copies of the original only. The only time I use jpg is for the web, or when I have no other choice. Shooting in RAW is best. The file is read-only and is comparable to a digital negative. I'm certain there are those out there who can explain this process better than me. My theory is "JPEGS ARE EVIL." :o)<br>

Joe</p>

<p>Changing the name does not degrade image quality. <em>It's duplicating the file to change the name that degrades quality</em>. Think of it this way: if you had a drawing and copied it in a copier 100 times, each copy would be the same quality because you are copying from a master. However, if you took copy #1 and used that to make copy #2 and so on, by the time you used copy #99 to make copy #100, you would have lost significant quality from that of your master before all the copying started.</p>

<p>So if I make a copy of the original through Photoshop CS5 and rename the copy and keep it as JPEG I lose quality?<br />Does right clicking and clicking "Save image as" in gmail while saving images that have been sent to me make those images lose quality?</p>

<blockquote>

<p>So if I make a copy of the original <strong>through</strong> Photoshop CS5 and rename the copy and keep it as JPEG I lose quality?<br>

<br />Does right clicking and clicking "Save image as" in gmail while saving images that have been sent to me make those images lose quality?</p>

</blockquote>

<p>Correct! Photoshop resaves the JPEG. Duplicate on the Finder and I'd suspect gmail duplicates the document, bit for bit (or thereabout's). </p>

<p>Peter, but I thought that copying from the original doesn't degrade image quality? Isn't a copy an exact copy of the data from the original? how would having a copy of the original and it just having a different name from the original such as changing it from "original" to "original copy" do anything to the data? So just changing the name of a copy degrades quality?</p>

<p>Andrew, So I am indeed losing quality of my JPEG files just by making a copy of them in Photoshop CS5 and renaming that copy something else? It wouldn't just stay the same as the original if I haven't done any editing to it or anything? <br />Also, regarding gmail, is right clicking and clicking "Save image as" degrading quality at all or no? I'll show you what I trying to say. http://i61.tinypic.com/14mayo7.png http://oi61.tinypic.com/15i7n14.jpg<br />See where it says "save as:" in the second link and it gives you the option to change the name of the photo before you save it? will changing the name of the JPEG file that was sent to me from someone via gmail before it is saved degrade the quality?</p>

<p>More precisely, NTIM, it's re- and re-re-compressing the file <strong><em>through the jpeg engine</em></strong> that causes loss of quality. <em>Just</em> copying it (by dragging or such) or re-naming does not call up the compression routines in any form.</p>

<p>How would you and what would cause compression?</p>

<p>It is the re-saving of a file in the jpg format that causes the quality loss whether it was changed or not. Every time Photoshop (or any editor) saves as a jpeg, it compresses the image file a bit more even at maximum quality. Simply re-naming an unopened file causes no loss.</p>

<p>Would it cause loss to the original or to the copy of the original? The original was opened in photoshop and a copy of it was made and renamed in photoshop and sent to me. So would the copy that was sent to me be the degraded image or would his original copy that he opened in photoshop to make a copy of be?</p>

<p>How much quality would be lost by just copying a original image in photoshop and renaming the copied image without any editing?</p>

<p>Em-re your first 2 questions, why don't you just try it and see for yourself? Re your 3rd question, I don't know if you already have photoshop but if you do, again, try it and see. cb</p>

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<p>How much quality would be lost by just copying a original image in photoshop and renaming the copied image without any editing?</p>

</blockquote>

<p>It depends on how you have the compression settings set when you save the new version of the file. But really, you're worrying way too much about that. If all you want is a copy of the image file, just use your computer's file system to make a copy of the file. That will be a perfect copy. Why would you open a file in an editing program just to copy it? All that does is slow you down - just like it makes no sense to open a document in a word processor or spreadsheet program just so you can make a copy of it. Just do it at the file system level, and you're done, and there's no software getting involved in re-working the JPG file's compression as you look at it in a editor.<br /><br />I'm trying to read between the lines in your questions. Did you open and save over top of the only copies you have of a client's files? There's simply no need to worry about all of this unless you've damaged files that are the only copies that exist. But if they're attached to email sent to you, you've still got the originals, attached to the email. Just save them, again.<br /><br />On that note: don't forget that you need to have in place a solid backup process that will keep you extra copies of everything you work with, in case you slip up and destroy something that can't be replaced.</p>

<p>No, the issue is, I ordered a photo from a photographer and noticed he had sent me a copy of the original photo(noticed the name was different from the original) and under inspector i noticed it said it was opened in photoshop, I asked him about this and he said he opened it in photoshop to look at it but i'm pretty sure he made a copy of it in photoshop so i wanted to know if the copy he sent me is lesser quality than the original he has?</p>

<p>When one "opens" a file in Photoshop, or other image processing software...what you see a memory version of the image itself. If you then "close" the file....the memory version closes without any effect on the original file. On the other hand, if you open the file and then "save" it to create a copy, the software applies compression to the version it held in memory; if you keep the same name and format, then you end up with your original being further compressed; if you change the name or format (thru the "save as" command), nothing happens to your original file, but the software procesess the version held in memory and applies compression. Merely "copying" a file with another name by other means, does not apply compression to the copy or original. I hope this clears up your confusion.</p>

<p>So did the copy I received lose quality? if he made a copy of the original in photoshop and sent the copy to me, does my copy have loss quality or is it the same quality as the original? How I know he sent me a copy is the file name is different from the original file and under inspector it says my copy was opened in photoshop the day he sent it to me via email. Sorry, this is all really confusing to me. </p>

<p>You would need to compare file sizes at the very least. As I mentioned earlier, merely "opening" a file and closing it (not "saving" it) doesn't change its characteristics. Why not ask the person you got it from how he made the copy you have.</p>

<p>Because he's being unprofessional and not answering me</p>

<p>Does opening a file and saving it even without making any changes or edits make the file lose quality though?</p>

<p>Personally I wouldn't worry about it - even though you purchased it, unless the purchase contract is specific that there would be no physical changes to the image quality. Unless there was a significant purposeful change in compression, it would generally be virtually unnoticeable in the 1st generation of copies.</p>