Why are Sketch photos smaller?

Question

Design

Why, when I open a file in Photoshop, its size is 4000 pixels, and when the same photo is exactly 2 times smaller? And so with all sizes.

Answer 1

Because Sketch will subsequently generate two (or more, depending on the settings) images from your bitmaps, one with a size of 0.5 for normal screens, the second with an @2x suffix for retina.