Face searching and detection in a digital image acquisition device

Abstract

A method of detecting a face in an image includes performing face detection within a first window of the image at a first location. A confidence level is obtained from the face detection indicating a probability of the image including a face at or in the vicinity of the first location. Face detection is then performed within a second window at a second location, wherein the second location is determined based on the confidence level.

1 .- 20 . (canceled) 
     
     
         21 . A method comprising: acquiring data of a digital image which depicts one or more objects; determining a first size of a first detection window and an initial location of the first detection window in the digital image; wherein the first detection window encompasses a first portion of the digital image; determining, for the first detection window, first detection window data that represents the first detection window at a first image resolution level; determining a first set of face detection tests that are to be applied to the first detection window data; applying the first set of face detection tests to the first detection window data to determine a first confidence level value that indicates a likelihood that a particular object, of the one or more objects, is included in the first detection window; in response to determining that the first confidence level value is not greater than a first threshold value: determining a second size that is greater than the first size; determining a second detection window that has the second size; wherein the second detection window encompasses a second portion of the digital image; determining, for the second detection window, second detection window data that represents the second detection window at a second image resolution level; determining a second set of face detection tests that are to be applied to the second detection window data; and applying the second set of face detection tests to the second detection window data to determine a second confidence level value that indicates a likelihood that the particular object, of the one or more objects, is included in the second detection window; and wherein the method is performed using one or more computing devices. 
     
     
         22 . The method of  claim 21 , further comprising: in response to determining that the second confidence level value is greater than a second threshold value, determining that the particular object, of the one or more objects, is depicted in the second detection window. 
     
     
         23 . The method of  claim 22 , further comprising: in response to determining that the second confidence level value is not greater than the second threshold value: determining a second location by rotating the second detection window; determining a third detection window, wherein the third detection window has the second size and is located at the second location; determining, for the third detection window, third detection window data; determining a third set of face detection tests that are to be applied to the third detection window data; and applying the third set of face detection tests to the third detection window data to determine a third confidence level value that indicates a likelihood that the particular object, of the one or more objects, is included in the third detection window. 
     
     
         24 . The method of  claim 23 , further comprising: in response to determining that the third confidence level value is greater than a third threshold value, determining that the particular object, of the one or more objects, is depicted in the third detection window. 
     
     
         25 . The method of  claim 24 , further comprising: in response to determining that the first confidence level value is greater than the first threshold value: determining a fourth set of face detection tests that are to be applied to the first detection window data; wherein the fourth set of face detection tests comprises a chain of classifiers to be applied to the first detection window data to determine a skin map; and applying the fourth set of face detection tests to the first detection window data to determine a fourth confidence level value that indicates a likelihood that the particular object, of the one or more objects, included in the first detection window, is a face. 
     
     
         26 . The method of  claim 25 , wherein the fourth set of face detection tests comprises one or more frontal face detection tests. 
     
     
         27 . The method of  claim 26 , wherein the skin map comprises a map of values computed for each pixel of the first detection window; and wherein a particular value in the skin map represents a probability that a particular pixel of the first detection window depicts a portion of a human skin. 
     
     
         28 . A non-transitory computer-readable storage medium, storing one or more instructions which, when executed by one or more processors, cause the one or more processors to perform: acquiring data of a digital image which depicts one or more objects; determining a first size of a first detection window and an initial location of the first detection window in the digital image; wherein the first detection window encompasses a first portion of the digital image; determining, for the first detection window, first detection window data that represents the first detection window at a first image resolution level; determining a first set of face detection tests that are to be applied to the first detection window data; applying the first set of face detection tests to the first detection window data to determine a first confidence level value that indicates a likelihood that a particular object, of the one or more objects, is included in the first detection window; in response to determining that the first confidence level value is not greater than a first threshold value: determining a second size that is greater than the first size; determining a second detection window that has the second size; wherein the second detection window encompasses a second portion of the digital image; determining, for the second detection window, second detection window data that represents the second detection window at a second image resolution level; determining a second set of face detection tests that are to be applied to the second detection window data; and applying the second set of face detection tests to the second detection window data to determine a second confidence level value that indicates a likelihood that the particular object, of the one or more objects, is included in the second detection window.