Q: What is a Lossless Date Stamp?
A: JPEG is a lossy image compression format. So if a software
de-compresses the entire jpeg file to pixels to put the date stamp
and re-compresses it to back to the jpeg format there will be minor
differences at the pixel level in the entire image though you
have added a date stamp only in a corner. Jambula is a
specialized software that uses Jpegtran to extract and add the
date stamp only in the small rectangular area required and then
drops back the stamped section onto the original image. So the
pixels outside the stamped area are exactly the same thus
preserving the original image quality.
Q: Where does Jambula get the Date/Time info from?
A: It gets it from Meta Data stored in the jpeg files by
digital cameras called EXIF. In case the EXIF header is missing
Jambula stamps the Last Modified Time of the File
Q: Since the picture date and time is already there in the
header is it required to add a Date Stamp to my photos?
A: It is good to have the original image without any water
mark. However it is useful to create a Date Stamped copy
of all or selected pictures for uses like taking prints and
showing in a digital photo frame.