Image Processing Method, Image Displaying Method, Image Processing Device, and Image Displaying Device

An image processing method includes: capturing, by a first image capturing device installed at a position located on a side surface outside a vehicle interior of a vehicle and anterior to a rear end of the vehicle, a first image, the first image being an image of a region including a rear lateral side of the vehicle; capturing, by a second image capturing device installed on a rear end of the vehicle, a second image, the second image being an image of a region in a rear of the vehicle; generating a synthetic image serving as an image of a rear view of the vehicle by synthesizing the first image and the second image with each other; and superimposing an outline, the outline being a line segment extending along a contour of a side surface of the vehicle, in the synthetic image.