1. A method for generating depth-of-field effects, the method comprising: receiving a first image comprising a value at each point of the first image; receiving a second image indicative of a first circle of confusion at each point of the first image; and generating a third image in response to simulating heat diffusion using an implicit solution to a heat equation using an initial heat for the heat equation based on the value at each point of the first image and thermal conductivity for the heat equation based on the first circle of confusion at each point of the first image.