If after downloading the photos from your camera you notice that they have a wrong time, you can offset the date taken by a constant amount with no loss of image quality:
- Start FreeVimager.
- Choose File - Batch Processing...
- As input select your picture's folder or choose the files you want to modify by adding them to the list.
- As output set a different directory (if you choose the same location the files are overwritten, it's dangerous to do so if you do not have a backup copy of your pictures).
- Disable Rename if you want to keep the original file names.
- Enable Conversion, select Advanced Settings, check Date Taken Shift and set the wanted offset.
- Under the Shrink tab make sure that Enable Image Size Shrinking is not checked.
- Press the Start button.
Hint: verify the time of the processed pictures in the File Info dialog.