Rotating images explained
A 90° turn to the right fixes a photo that was taken sideways, a 90° turn to the left does the opposite, and a 180° rotation turns an upside-down picture the right way up. A 270° rotation is the same as 90° to the left. These quarter turns move every pixel to an exact new position, so the image is simply re-oriented: its width and height swap for 90° and 270° turns, and nothing is stretched or cropped.
