Windows 7: Explorer Changes Compresses jpg files after Date Change

I can not believe this is happening. I right click on a 744KB jpg file, select Properties > Details and I correct the date which was incorrectly set in the camera. Then I click OK or Apply. Now the file size is down to 334KB. Explorer has recompressed the file on some lower quality setting! I over-layed the file in Photoshop on top of a copy of the orig 744KB file and there are significant differences. I checked and the same thing happens to all jpg files. Is there some hidden default setting in Windows that can be changed to prevent this behavior? Is this a Windows bug?

Yes, Explorer does it in a weird way. It changes quality and also adds an Adobe XMP tag. I think, compression level is hardcoded here like in MsPaint.


This issue has been duscussed by Seven Gurus on this forum and elsewhere. IMHO, the best advice is to avoid using Explorer for changing attributes.

To change date in a photo properly, I would recommend a free program called XnView (Minimal version would do).

It allows to change date without problems (menu Tools - Change timestamp). And you can change date for multiple pictures at a time!

Neutron, thanks very much for the reply. That's what I expected. I am incredibly ticked off at MS. The Explorer behavior is totally unintuitive and unexpected. When you make these kind of Exif changes in Adobe Bridge, Camera RAW, and a long list of other programs the image block is not modified and that is what I would expect. I had already changed a dozen or so files and only by accident did I notice it. At minimum I would expect MS to have some warning that about the changes.
Well, lesson learned - another reason to distrust MS.
Cheers, Murray