Method replacesthe tag value if the tag is present in the metadata tree, or null otherwise.

This method accesses the DateTimeDigitized tag. The tag specifies the date and time when the image was stored as digital data. If, for example, an image was captured by DSC and at the same time the file was recorded, then the DateTimeOriginal and DateTimeDigitized will have the same contents. The format is "YYYY:MM:DD HH:MM:SS" with time shown in 24-hour format, and the date and time separated by one blank character [20.H].