JPG files changing size on me

I am at the end of a photo-editing project. I am going back and adding titles/descriptions to some of the pictures. Quite by accident I noticed that when I add a title Windows is changing the size of the file on me.

The change doesn't show until I leave the folder and go back in. Well, of course you're saying, you add some detail and it will increase the file size by a few kb. Unfortunately it is reducing the file of every one I'm doing this to. One example is from 305kb down to 267kb, almost 1/3.

I don't notice a change in the picture when I view it, but that isn't really the point. Why is it doing this and can I get it to stop?

What editor are you using.
jpeg encoding is a lossy encoding algorithm. Every time you decode-edit-encode you will get some image degradation even when the maximum quality (low loss) re-encoding option is selected and the image file will generally be larger.
In your case you must have the re-encoding quality set lower or changed the resolution resulting in a smaller file size.

I'm done "editing". I was just using Windows Explorer to list the files, and add a "title" at the bottom of the screen where the file information (date taken..size etc) is listed.

I was aware of the issues with jpeg degradation but with over 10,000 pictures total file size was an issue.

While I am technically "editing" the file, I'm not editing the picture itself, so I am confused as to why Windows is reducing the size of the file on me. I'm not even opening in it a viewer, just changing data. It is doing the same thing if I right click on the file, go into properties and add the title there. It should not be appreciably changing the file size on me.

I tried what I think you were doing and my jpgs increased slightly in size. I assume it was only writing some metatdata to the file.

And that's what I would have expected, a small increase, not a substantial decrease. I am going to play with it on an XP machine, because this wasn't happening early in my project. Something is happening that shouldn't be, and I need to stop it.

The XP did the same thing. Didn't decrease it to the exact same size, but pretty close. I kept a full backup on there so I could check the same file. It did update the size immediately as opposed to having to re-enter the folder on Windows 7, but that was about the only difference.

Because of size constraints to fit these on flash drives for relatives (lucky them), I did subject them to a batch size reduction with one editor, and I'm thinking now it may have caused some kind of instability with the individual files. Because I had some that were not reduced and I can add the title on XP with no size change, and on 7 with a small size increase.

Looks like I'm stuck with what I have. Any other thoughts would be appreciated.

mitchell65 said:

When you say "I did subject them to a batch size reduction with one editor,"
Did you use Adobe Elements for this by any chance?

I used trialware programs from Nikon and Corel for the all of the actual editing. The bulk of the reductions were done with one of those 2 (don't remember which one). I did my last batch of reductions with a freeware program PhotoScape (no actual editing with it).

The first batch is decreasing in size a lot. The second batch is increasing in size a little.

I think Mitchell65 has got it. If say, on the 1-12 scale, 9 was save and compress to 75%, if you renamed the same file half a dozen times and it was compressing to 75% of its original, your final image would be under 20% the size (quality) of the original (first) jpeg image. One reason I never touch them if I can help it! I'm sure its lossy bit is embedded in its metadata telling it to lose unnecessary bits every time.