Image processing method, image processing apparatus, and image processing program

An image processing apparatus for correcting an average brightness density value of a photographic image that includes a facial region obtained by photography so that it matches a predetermined reference value, comprising:

• detecting means for detecting the facial region from within the photographic image;
• judging means, for judging whether a brightening correction or a darkening correction is to be administered on the photographic image, by comparing the average brightness density value of the photographic image against the predetermined reference value;
• and
• correcting means, for correcting the photographic image so as to generate a corrected image having corrected pixel signal values, which are the pixel signal values of the photographic image corrected by a predetermined correction amount, only in the case that the judging step judges that a brightening correction is to be administered on the photographic image;
• wherein:
• the judging means obtains the average pixel signal value from within the detected facial region;
• the correcting means gradually decreases the correction amount for pixel signal values that represent the brightness of pixels, which are greater than or equal to a predetermined brightness, as the brightness of the pixels increases such that the corrected pixel signal values are not saturated in a direction of brightness.

A computer readable medium having stored thereon a program that causes a computer to execute an image processing method for correcting an average brightness density value of a photographic image that includes a facial region obtained by photography so that it matches a predetermined reference value, comprising:

• a detecting procedure, for detecting the facial region from within the photographic image;
• a judging procedure, for judging whether a brightening correction or a darkening correction is to be administered on the photographic image, by comparing the average brightness density value of the photographic image against the predetermined reference value;
• and
• a correcting procedure, for correcting the photographic image so as to generate a corrected image having corrected pixel signal values, which are the pixel signal values of the photographic image corrected by a predetermined correction amount, only in the case that the judging step judges that a brightening correction is to be administered on the photographic image;
• wherein:
• the judging procedure obtains the average pixel signal value from within the detected facial region;
• the correcting procedure gradually decreases the correction amount for pixel signal values that represent the brightness of pixels, which are greater than or equal to a predetermined brightness, as the brightness of the pixels increases such that the corrected pixel signal values are not saturated in a direction of brightness.

An image processing method for correcting a brightness density of a photographic image having a facial region, comprising:

• receiving pixel signal values representing the photographic image;
• detecting, using a processor, the facial region from within the photographic image;
• calculating pixel signal brightness density values Y for each pixel signal value in the detected facial region;
• calculating, using a processor, an average brightness density value Yaverage for the detected facial region;
• comparing, using a processor, the average brightness density value Yaverage against a predetermined reference density value Ytarget;
• determining, using a processor, whether a brightening correction or a darkening correction is to be administered on the photographic image, based on said comparison;
• and
• only if it is determined that a brightening correction is to be administered on the photographic image, then correcting the photographic image by correcting the pixel signal brightness density values by a predetermined correction amount,
• wherein the predetermined correction amount gradually decreases as the pixel signal brightness density value increases, for pixel signal brightness density values which are greater than or equal to a predetermined brightness such that the corrected pixel signal values are not saturated in a direction of brightness.