A method for operating an image sensor with a 4 rows×4 columns pixel group including 4 sub-pixel groups each including 4 pixels of 2 rows×2 columns includes: selecting and reading out a first pixel among 4 pixels in a first row of the pixel group; selecting and reading out, in a second row of the pixel group, a second pixel from a sub-pixel group other than a sub-pixel group including the first pixel; selecting and reading out, in a third row of the pixel group, a third pixel from a column other than a column including the first pixel and a column including the second pixel; and selecting and reading out, in a fourth row of the pixel group, a fourth pixel from a column other than the columns including the first pixel, the second pixel and the third pixel.