post-mortem photograph meaning in Information Science terminology / glossary / dictionary is:
A photographic image of a deceased person or pet, made after death. Post-mortem photographs were taken as early as 1839, to be preserved as keepsakes by the bereaved (see this example, courtesy of the Tate Gallery). The corpse is usually presented in a lifelike or resting pose, sometimes in the casket and/or accompanied by living members of the family or friends (example). The term is also used for photographs taken of the bodies of people killed by accident, in war, or as a result of a crime, sometimes for forensic purposes. Also spelled postmortem. Synonymous with death portrait. Compare with memorial photograph.