Image processing method and image processing apparatus for making luminance correction

An image processing method for discriminating an exposure state of image data on the basis of a luminance histogram which indicates a distribution of luminance level of the image data and is generated from the image data, comprising the steps of:

• calculating a luminance deviation value indicating a distribution state of luminance level from the luminance histogram;
• detecting one or more peaks from the luminance histogram;
• calculating a peak distance value which indicates the longest distance between peaks in the case that plural peaks exist so that plural distances between respective peaks exist;
• and
• discriminating that the image is a backlight image when the luminance deviation value is greater than or equal to a first predetermined value and the peak distance value is greater than or equal to a second predetermined value.

An image processing apparatus for discriminating an exposure state of image data on the basis of a luminance histogram which indicates a distribution of luminance level of the image data and is generated from the image data, said apparatus comprising:

• a luminance standard deviation unit which calculates a luminance deviation value indicating a distribution state of luminance level from the luminance histogram;
• a peak distance obtaining unit which detects one or more peaks from the luminance histogram;
• and
• an exposure discriminating unit which calculates a peak distance value which indicates the longest distance between peaks in the case that plural peaks exist so that plural distances between respective peaks exist;
• and discriminates that the image is a backlight image when the luminance deviation value is greater than or equal to a first predetermined value and the peak distance value is greater than or equal to a second predetermined value.