Why does the size of an image decrease with drag-moving?

[OneJuan]

Hello, I have found myself in a quite frustrating situation.

I have been sorting out my files and I noticed that some of the photographs decreased in size when I drag-moved them from the folder "My pictures" to another folder on my local HDD.

For example: One of the photographs used to be 5.18MB and is now 4.73MB. The resolution stayed the same: 6000x4000 and when I compare the photos (I did a back up before moving the files around) in windows photo viewer there is no difference whatsoever. Also when I check the colour graph in Adobe Lightroom there is no difference in files.

Why did the file size decrease? Should I be worried or is it possible that some useless metadata dissapeared when I drag-moved the photographs?

Thank you

Juan

 

[TrainableMan]

If you are moving files from one drive to another size difference can often be explained by differences in the sector size of the drives.

But for pictures moving within the same drive my best guess is that you are loosing metadata.