1. Technical Field
The present invention relates to pattern recognition and object recognition techniques and, more particularly, to a human face detection position deviation-correcting method, correcting system, and correction program capable of detecting whether a detected human face has deviated in position and of correcting the position.
2. Related Art
In recent years, as pattern recognition technology and information-processing apparatuses such as computers have improved in performance, the accuracy at which characters and voice are recognized has improved at an amazing rate. It is known, however, that it is still difficult to recognize persons, objects, and scenes within images taken, for example, by a still image camera by pattern recognition technology, and that it is especially quite difficult to precisely and quickly recognize whether a human face is contained in such an image.
However, it has become quite important to recognize whether a human face is contained in such an image and to identify who is in the picture precisely and automatically using a computer in establishing biometric recognition technology, improving security, speeding up criminal investigations, increasing the rates at which image data are put in order, and speeding up search operations.
Meanwhile, in the case of ordinary users who are fond of photography and designers professionally engaging in image processing, they frequently want to make layouts about the subject human face from the taken digital photograph. In one case, for example, a picture where the face has been zoomed in is created from a picture containing the entire human body. In another case, a picture for a personal history is created.
In such cases, it is necessary to zoom into the face while precisely aligning the center of the face or to align the center of the face to the center of the photograph frame manually. Hence, complex and skilled operations are necessary.
Therefore, in the past, a method of detecting the position of a face using a facial image detection technique and aligning the position of the facial image has been proposed.
For example, in H. A. Rowley, S. Baluja, and T. Kanade, “Neural network-based face detection”, IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 20, No. 1, pp. 23-38, 1998, there is disclosed a technique for detecting a facial image by training a neural network using facial images.
Furthermore, in the above paper and so on, a decision is first made as to whether there is any region of human flesh color within an input image. A mosaic size is automatically determined about the region of human flesh color. A mosaic candidate region is created. The proximity to the dictionary of human faces is calculated. Thus, a decision is made as to whether there is a human face. The face is extracted. This reduces erroneous extraction due to the effects of the background. Consequently, human faces are found from images automatically and efficiently.
With the method of the above-cited paper, it is possible to detect a facial image but there is the problem that the center of the position of a human face can not always be precisely calculated as disclosed in the paper.
On the other hand, in JP-A-H9-171560, it is necessary to calculate the center line of the rotation while creating data about rotation of the face. Hence, there is the anxiety that the processing time is increased. Furthermore, it is assumed that every assumed pixel has symmetry. Therefore, it is quite difficult to stably gain the center line due to noise.
Accordingly, the present invention has been devised to effectively solve these problems. It is an object of the present invention to provide a novel human face detection position deviation-correcting method, correcting system, and correcting program capable of judging whether a detected human face has deviated from the detection position and of correcting the positional deviation from the detection position by a quick and simple method.