Hi

is there any way to add date and time to camera picture.?

It's in the EXIF metadata of the picture file so why on earth would we want to "burn" that info to the actual image ?

we can categorize images , wen we create an album

Create album how exactly ? about the only case where burned dates would be "usefull" is if you got prints first and thought about organizing them later.

Just about any image viewer should have some sort of "show info" option somewhere that will show all the EXIF data and all sane album software should be aware of this data as well (for example iPhoto automatically organizes the photos by date and uses the EXIF data).

If your album software cannot read or make good use of the extensive metadata available I recommend finding another album software to use.

Edit: OTOH if you really want to burn the dates on the images it should be fairly simple with a small shell script using imagemagick (or make a small python program to do it), both can be hooked to the camera lens close DBUS notification and then check files that have been created "short time ago".