The present invention generally relates to image processing technologies. More particularly, the invention relates to image correcting apparatuses, methods and programs that correct images on which persons are photographed.
In preparing photo prints from digital image data, which is, for example, acquired by photo shooting with a digital camera, or obtained by photo-reading of an image printed on a photo film, correction may be performed on the images so that the images are reproduced with appropriate colors and densities. In particular, when it comes to images on which persons are photographed, it is significantly important to reproduce face colors appropriately.
There have been known image processing methods that place an importance on skin colors of persons, including, for example, a technology (refer to JP 2000-196890 A, for instance) in which a person face is automatically extracted from image data and the data is corrected so that a skin color of the face area achieves a target range of density, and a technology (refer to JP 2000-182043 A, for instance) in which a skin color of the face area achieves target chromaticity. In these technologies, a target density and/or a target chromaticity of skin colors are pre-set and the images are corrected respectively in such a manner that the density and/or color of the face regions extracted from the image data are close to the target values.
However, considering that different persons from different races have different skin colors, there may be problems if a certain color and/or density is used as a akin color target for correcting all the images of an image group, when the images include different persons from a plurality of races and are shot under identical shooting conditions (such as class book photos). For example, there may be inconsistency in background colors among the images or skin color tint may not always be appropriately reproduced. Therefore, it is desirable to perform identical correction to an image group consisting of such a plurality of images.
In JP 6-208178 A, on the other hand, a photo printing method, in which, a printing exposure amount for a plurality of frame images is determined based on an average value of measured light values, and the determined printing exposure amount is used to print the plurality of frames onto printing paper is described. In this method, since a same printing exposure amount is used to print the plurality of frames, inconsistency in background colors among the images shot under identical shooting conditions can be prevented.
However, on the contrary, in case where skin colors are varied due to different shooting conditions, there may be some frames in which skin colors are not reproduced appropriately.