I thought it was the people in the pictures that were dead at first, too... but then when the disintegration happens it made me think it was the other way. The person looking at the photograph is dead, and they are getting a chance to see a loved one again. When the loved one first sees them, they cry (which is why the second person in each pairing cries first). Then the dead person cries and realizes they are dead and then they disappear.
Boom. Blew your mind.