Patent ID: 7570840

Claim:
A method of determining based on image data whether an image is a backlit image, the method comprising using a processor to perform operations of; acquiring the image data; analyzing the acquired image data to determine whether the image is a backlit image; analyzing the acquired image data to determine whether a ratio of number of dark outer area pixels having luminance not larger than reference luminance to total number of outer area pixels is not larger than a first predetermined value, the outer area pixels being other than inner area pixels among all pixels constituting the image data, the inner area pixels constituting image data corresponding to a central portion of the image; analyzing the acquired image data to determine whether a ratio of number of bright outer area pixels having luminance not smaller than the reference luminance to the total number of outer area pixels is not smaller than a second predetermined value; and concluding that the image is a backlit image if the image is determined to be a backlit image, the ratio of number of dark outer area pixels having luminance not larger than the reference luminance to the total number of outer area pixels is not larger than the first predetermined value, and the ratio of number of bright outer area pixels having luminance not smaller than the reference luminance to the total number of outer area pixels is not smaller than the second predetermined value, wherein the determination whether the image is a backlit image includes: determining whether a ratio of number of flesh color pixels among the inner area pixels to the total number of the inner area pixels is not smaller than a third predetermined value; determining whether average luminance of flesh color pixels among the inner area pixels and the outer area pixels is not larger than a fourth predetermined value; and determining that the image is a backlit image if the ratio of number of flesh color pixels among the inner area pixels to the total number of the inner area pixels is not smaller than the third predetermined value, and the average luminance of flesh color pixels among the inner area pixels and the outer area pixels is not larger than the fourth predetermined value.