This is a "vanitas", a traditional form of still life (and portraiture) that contains a symbol of death--like a skull, an overturned goblet, an extinguished candle et al.
These painting were very popular in the 15th and 16th centuries in the Netherlands and Flanders. And no, it doesn't mean i'm depressed--I just think skulls make cool subjects for still lifes!
This was done in Photoshop and combines many photographic elements with digital painting. The final piece was printed on watercolor paper using archival inks.