How is it that two different images, but same resolution, can have different storage size?

Question

How is it that two different images, but same resolution, can have different storage size?

In: Technology

Answer 1

Digital compression algorithms!
There are a bunch of different ways to do it. A common method is the only store the differences

Let’s say you take a picture of a cloud in the sky. There is a lot of white and a lot blue. We don’t need to store red and green info in the picture cause its never used individually

Additionally the same blue and same white are re used, so we can just say where the blue is and white is rather than : blue here, white here, blue here , blue here, …