Late 80s Horror Movie with Possessed Guy who is an Amnesiac

I saw this movie I think in the late 80's (85-88).

The movie is very dark and more or less a guy seems to be possessed. Someone makes an unpleasant comment to him at day and at night he goes for the kill.

Things I remember from the movie:

-The guy is an (amateur?) painter and paints a portrait of a (female?) demonic or witch like face.
The portrait really looks evil and sometimes bleeds. It evolves throughout the movie and gets worse.

-When he is out for the kill he seems possessed: his face has green glowing eyes.

-Sometime we see the movie in the first person and the environment looks greenish and compressed/ distorted.

-At some point he tries to commit suicide (in the beginning of the movie I think) but survives however and becomes an amnesiac.

I think later on we learn the background (he has flash backs in the movie where he discovers more and more about himself).

-One kill is someone crushed against a wall by a forklift with a heavy load in a factory.

-Another kill is in a slaughterhouse: a guy is cut in half by a saw vertically while trapped in a cow body.

Does anyone know what the title of this movie is?