Method and system for face detection in digital images

A digital image processing method for detecting faces in a digital color image, said method comprising the steps of:

• providing a distributed face detection system having N complementary classifiers, wherein the classifiers are complementary in a frequency domain;
• selecting classifier parameters for the complementary classifiers from a plurality of different parameter generating sources, at least one of which is controllable by human input;
• reconfiguring the complementary classifiers in the distributed face detection system according to the selected classifier parameters, such that only M of the N complementary classifiers are involved in face detection, wherein M and N are integers, M is less than N, and M is greater than zero;
• and
• detecting faces using the M complementary classifiers in the distributed face detection system,
• wherein the step of providing a distributed face detection system having complementary classifiers comprises the steps of:
• constructing one or more classifiers having high execution speed and featuring operation in one portion of the frequency spectrum of the digital image;
• and
• constructing one or more classifiers having high accuracy and featuring operation in another portion of the frequency spectrum of the digital image,
• wherein the step of constructing one or more classifiers having high execution speed and featuring operation in one portion of the frequency spectrum of the digital image comprises the step of constructing a grid pattern classifier, and
• wherein the step of constructing a grid pattern classifier comprises the steps of:
• generating a mean grid pattern element (MGPe) image from a plurality of sample face images;
• generating an integral image from the digital color image;
• locating faces in the digital color image by using the integral image to perform a correlation test between the mean grid pattern element (MGPe) image and the digital color image at a plurality of effective resolutions by reducing the digital color image to a plurality of grid pattern element images (GPes) at different effective resolutions and correlating the MGPe with the GPes.

A digital image processing method for detecting faces in a digital color image, said method comprising the steps of:

• providing a distributed face detection system having complementary classifiers, wherein the classifiers are complementary in a frequency domain;
• selecting classifier parameters for the complementary classifiers from a plurality of different parameter generating sources, at least one of which is controllable by human input;
• reconfiguring the complementary classifiers in the distributed face detection system according to the selected classifier parameters;
• and
• detecting faces using the distributed face detection system,
• wherein the step of providing a distributed face detection system having complementary classifiers comprises the steps of:
• constructing one or more classifiers having high execution speed and featuring operation in one portion of the frequency spectrum of the digital image;
• and
• constructing one or more classifiers having high accuracy and featuring operation in another portion of the frequency spectrum of the digital image,
• wherein the step of constructing one or more classifiers having high execution speed and featuring operation in one portion of the frequency spectrum of the digital image comprises the step of constructing a grid pattern classifier, and
• wherein the step of generating an integral image further comprises the steps of:
• replacing non-skin-color pixels with black to produce an image C having skin color pixels;
• replacing non-face-shaped clusters with black to produce an image E having skin colored face shaped clusters;
• labeling clusters of skin colored face shaped clusters;
• and
• generating the integral image from each cluster of the image E.

A digital image processing method for detecting faces in a digital color image, said method comprising the steps of:

• providing a distributed face detection system having N complementary classifiers, wherein the classifiers are complementary in a frequency domain and comprise one or more classifiers having high execution speed and featuring operation in one portion of the frequency spectrum of the digital image, and one or more classifiers having high accuracy and featuring operation in another portion of the frequency spectrum of the digital image;
• providing classifier parameters for the complementary classifiers from a plurality of different parameter generating sources dependent upon conditions of he digital image;
• and
• detecting faces using any desired combination of only M of the N complementary classifiers in the distributed face detection system, wherein M and N are integers, M is less than N, and M is greater than zero;
• wherein the one or more classifiers having high accuracy and featuring operation in another portion of the frequency spectrum of the digital image are provided by:
• constructing a cascaded classifier, and constructing a Bayesian classifier.

A digital image processing system for detecting faces in a digital color image, said system comprising:

• a distributed face detection system having N complementary classifiers, wherein the classifiers are complementary in a frequency domain;
• a plurality of different parameter generating sources for selecting classifier parameters for the complementary classifiers, wherein at least one of the sources is controllable by human input;
• and
• means for reconfiguring the complementary classifiers in the distributed face detection system according to the selected classifier parameters, such that any desired combination of only M of the N complementary classifiers are involved in face detection, wherein M and N are integers, M is less than N, and M is greater than zero;
• wherein the complementary classifiers include one or more classifiers having high execution speed and featuring operation in one portion of the frequency spectrum of the digital image, and classifiers having high accuracy and featuring operation in another portion of the frequency spectrum of the digital image;
• and
• wherein the classifiers having high accuracy and featuring operation in another portion of the frequency spectrum of the digital image include a cascaded classifier and a Bayesian classifier.