I’ll now focus on the second part of the question which is about the message that Hockney is trying to convey.
Hockney’s work is very much concerned with human vision and the way we perceive reality. As mentioned previously, his issue with photography is the single, static viewpoint that a regular photograph depicts. He also disliked the way there was a void between the photographer and the scene, which is why you’ll find his feet in some of his photographic collages.
The message in his photography, is that photography doesn’t have to be this static, frozen thing. He likened his style of photography to ‘drawing’ because he would make a lot of the same types of decisions.
About the cubism influence, he states it was about acknowledging that pictures are a perception of reality and not reality itself. He also says that cubism was the first time that subjects in art were not instantly recognisable – an animal or a person was depicted in a ‘non-standard’ way.
So, the message then, could be that what we see in a picture or a photograph is only a representation of what the creator perceives as reality.