When putting music to picture, you can either be congruent or incongrous. The music can be either in agreement with the visual emotion or against the grain. The score is the carrier of emotional subtext and can make connections which were not evident by image alone. How much is communicated is based on taste and talent of the composer and director.
Merriam Webster defines congruous as: being in agreement, harmony, or correspondence.
I sometimes refer to “against the grainness” as dissonance:
lack of agreement; especially : inconsistency between the beliefs one holds or between one’s actions and one’s beliefs. Going further you can compare this with the term COGNITIVE DISSONANCE which means: psychological conflict resulting from incongruous beliefs and attitudes held simultaneously. This cognitive dissonance can be played to great effect in filmmaking.
In the Stanley Kubrick classic “A Clockwork Orange”, horrible violence is accompanied by incredibly beautiful Beethoven music. This juxtaposition of gruesome visual with beautiful music creates a third space that is unique, memorable and scarily powerful. You truly enter the psyche of the thugs.
In the other direction, SONY’s Bravia commercial exudes a warm, floating feeling with a visual of 250,000 superballs released on the streets of San Francisco. The use of the song “Heartbeats” by Jose Gonzalez is a great congruent choice. The pacing, intimacy and quiet texture of Gonzalez’ voice and minimal guitar gives a great floating with motion quality to the piece.