1. A method comprising: calculating a first ratio of pixels having a skin color attribute in a first region of an image and a second ratio of pixels having the skin color attribute in a second region of the image, wherein the second region is inside the first region; determining whether the first ratio is larger than a first threshold value and the second ratio is larger than a second threshold value; and detecting a human face in a vicinity of a point inside the first region when the first ratio is determined to be larger than the first threshold value and the second ratio is determined to be larger than the second threshold value, wherein the second threshold value is larger than the first threshold value.