Face detection

Claim 1

A face detection apparatus generating an output indicative of the likelihood of test regions of a test image containing a face, the apparatus comprising: logic configured to derive a plurality of sets of image attribute data from a test region, each set relating to said test region scaled by a respective different scaling factor from a geometric progression of scaling factors, said progression being such that each scaling factor is related to a next scaling factor by a predetermined multiplicative factor, said factor being the same across the whole progression of scaling factors; a first comparator configured to compare said derived attributes for each scaling factor with a first respective set of attributes indicative of the presence of a face to generate a first respective likelihood value; a second comparator configured to compare said derived attributes for each scaling factor with a second respective set of attributes indicative of the presence of a face to generate a second respective likelihood value; said second sets of attributes are indicative of the presence of a central portion of a face in said test region; a generator configured to generate a combined likelihood value in respect of at least a subset of said scaling factors by combining the first likelihood value applicable to that scaling factor with the second likelihood value applicable to a further scaling factor separated from that scaling factor in the geometric progression by a predetermined number of positions; said generator is operable to combine the first likelihood value applicable to a scaling factor at which said test region represents a certain area of said test image with said second likelihood value applicable to a further scaling factor in which said test region represents a smaller area of said test image, and logic configured to derive a probability of the presence of a face at each scaling factor in the subset by a similarity between said derived attributes and said combined likelihood value in respect of that scaling factor.

Claim 9

A method of face detection for generating an output indicative of the likelihood of test regions of a test image containing a face, said method comprising: deriving a plurality of sets of image attribute data from a test region, each set relating to said test region scaled by a respective different scaling factor from a geometric progression of scaling factors, said progression being such that each scaling factor is related to a next scaling factor by a predetermined multiplicative factor, said factor being said same across the whole progression of scaling factors; comparing said derived attributes for each scaling factor with a first respective set of attributes indicative of the presence of a face to generate a first respective likelihood value; comparing said derived attributes for each scaling factor with a second respective set of attributes indicative of said presence of a face to generate a second respective likelihood value; said second sets of attributes are indicative of the presence of a central portion of a face in said test region; generating a combined likelihood value in respect of at least a subset of the scaling factors by combining said first likelihood value applicable to that scaling factor with said second likelihood value applicable to a further scaling factor separated from that scaling factor in said geometric progression by a predetermined number of positions; said generating combines the first likelihood value applicable to a scaling factor at which said test region represents a certain area of said test image with said second likelihood value applicable to a further scaling factor in which said test region represents a smaller area of said test image, and deriving a probability of said presence of a face at each scaling factor in said subset by a similarity between said derived attributes and said combined likelihood value in respect of that scaling factor.

Claim 10

A method of face detection for generating an output indicative of the likelihood of test regions of a test image containing a face, said method comprising: deriving a plurality of sets of image attribute data from a test region, each set relating to said test region scaled by a respective different scaling factor from a geometric progression of scaling factors, said progression being such that each scaling factor is related to a next scaling factor by a predetermined multiplicative factor, said factor being said same across the whole progression of scaling factors; comparing said derived attributes for each scaling factor with a first respective set of attributes indicative of the presence of a face to generate a first respective likelihood value; comparing said derived attributes for each scaling factor with a second respective set of attributes indicative of said presence of a face to generate a second respective likelihood value; said second sets of attributes are indicative of the presence of a central portion of a face in said test region; generating a combined likelihood value in respect of at least a subset of the scaling factors by combining said first likelihood value applicable to that scaling factor with said second likelihood value applicable to a further scaling factor separated from that scaling factor in said geometric progression by a predetermined number of positions; said generating combines the first likelihood value applicable to a scaling factor at which said test region represents a certain area of said test image with said second likelihood value applicable to a further scaling factor in which said test region represents a smaller area of said test image, and deriving a probability of said presence of a face at each scaling factor in said subset by a similarity between said derived attributes and said combined likelihood value in respect of that scaling factor.