Method for face orientation determination in digital color images
First Claim
1. A digital image processing method for locating faces in a digital image, comprising the steps of:
- generating an integral image from the digital image;
generating a grid pattern image from said integral image, said grid pattern image having a grid pattern having a plurality of cells each of said cells having a plurality of pixels;
reducing said grid pattern image to a corresponding base grid pattern element image, said base grid pattern element image having a number of pixels equal to the number of cells in said grid pattern image;
providing a set of different orientation images, said set including a selected one of said base grid pattern element image and a predetermined mean grid pattern element image of sample face images and excluding the other of said base grid pattern element image and said mean grid pattern element image, said set also including a plurality of additional grid pattern element images, each said additional grid pattern element image being a different rearrangement of elements of the selected one of said base grid pattern element image and said mean grid pattern element image; and
performing a correlation test between said images of said set of different orientation images and said excluded one of said base grid pattern element image and said mean grid pattern element image.
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Abstract
A digital image processing method for determining an orientation of a face in a digital color image generates a mean grid pattern element image from a plurality of sample face images and an integral image from the digital color image. A face is located in the color digital image by using the integral image to perform a correlation test between the mean grid pattern element 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 at different effective resolutions and correlating the mean grid pattern element image with the plurality of grid pattern element images, whereby either the mean grid pattern element image or the grid pattern element images are provided at a plurality of different orientations. Accordingly, an orientation of the face in the color digital image is determined by using the images with different orientations in the correlation test.
149 Citations
29 Claims
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1. A digital image processing method for locating faces in a digital image, comprising the steps of:
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generating an integral image from the digital image; generating a grid pattern image from said integral image, said grid pattern image having a grid pattern having a plurality of cells each of said cells having a plurality of pixels; reducing said grid pattern image to a corresponding base grid pattern element image, said base grid pattern element image having a number of pixels equal to the number of cells in said grid pattern image; providing a set of different orientation images, said set including a selected one of said base grid pattern element image and a predetermined mean grid pattern element image of sample face images and excluding the other of said base grid pattern element image and said mean grid pattern element image, said set also including a plurality of additional grid pattern element images, each said additional grid pattern element image being a different rearrangement of elements of the selected one of said base grid pattern element image and said mean grid pattern element image; and performing a correlation test between said images of said set of different orientation images and said excluded one of said base grid pattern element image and said mean grid pattern element image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A digital image processing method for locating faces in a digital image, comprising the steps of:
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generating an integral image from the digital image; generating a grid pattern image from said integral image, said grid pattern image having a grid pattern having a plurality of cells each of said cells having a plurality of pixels; reducing said grid pattern image to a corresponding base grid pattern element image, said base grid pattern element image having a number of pixels equal to the number of cells in said grid pattern image; providing a set of different orientation images, said set including said base grid pattern element image and a plurality of additional grid pattern element images, each said additional grid pattern element image being a different rearrangement of elements of said base grid pattern element image; and performing a correlation test between said images of said set of different orientation images and said mean grid pattern element image. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A digital image processing method for locating faces in a digital image, comprising the steps of:
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generating an integral image from the digital image; generating a grid pattern image from said integral image, said grid pattern image having a grid pattern having a plurality of cells each of said cells having a plurality of pixels; reducing said grid pattern image to a corresponding base grid pattern element image, said base grid pattern element image having a number of pixels equal to the number of cells in said grid pattern image; providing a set of different orientation images, said set including a predetermined mean grid pattern element image of sample face images and a plurality of additional grid pattern element images, each said additional grid pattern element image being a different rearrangement of elements of said mean grid pattern element image; and performing a correlation test between said images of said set of different orientation images and said base grid pattern element image. - View Dependent Claims (20, 21, 22, 23, 24)
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25. A digital image processing method for determining orientation of faces located in a digital color image, comprising the steps of:
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a) generating a mean grid pattern element image from a plurality of sample face images; b) generating an integral image from the digital color image; c) locating a face in the color digital image by using the integral image to perform a correlation test between the mean grid pattern element 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 at different effective resolutions and correlating the mean grid pattern element image with the plurality of grid pattern element images, whereby either the mean grid pattern element image or the grid pattern element images are provided at a plurality of different orientations; and d) determining an orientation of the face in the color digital image by using the images with different orientations in the correlation test of step c); wherein the step a) of generating a mean grid pattern element image comprises the steps of; a1) collecting sample face images; a2) generating a mean face image from the sample face images; a3) selecting a regular grid pattern; a4) reducing the resolution of the mean face image to the resolution of the selected grid pattern by averaging; and a5) generating mean grid pattern element images with different orientations by rearranging the order of the elements; and wherein the step of selecting a regular grid pattern comprises computing a distance between two eye centers of the mean face image;
computing a center position between the two eye centers; and
using the distance and position to determine M and N dimensions and a position of a region wherein said region contains M by N grid cells with each cell having m by n pixels.
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26. A digital image processing method for determining orientation of faces located in a digital color image, comprising the steps of:
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a) generating a mean grid pattern element image from a plurality of sample face images; b) generating an integral image from the digital color image; c) locating a face in the color digital image by using the integral image to perform a correlation test between the mean grid pattern element 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 at different effective resolutions and correlating the mean grid pattern element image with the plurality of grid pattern element images, whereby either the mean grid pattern element image or the grid pattern element images are provided at a plurality of different orientations; and d) determining an orientation of the face in the color digital image by using the images with different orientations in the correlation test of step c); wherein the step b) of generating an integral image further comprises the steps of; b1) replacing non-skin color pixels in the digital color image with black to produce an image having skin color pixels; b2) replacing non-face shaped clusters of pixels with black to produce an image having skin colored and face shaped clusters; b3) labeling skin colored and face shaped clusters as face clusters; and b4) generating the integral image from each labeled face cluster of the image. - View Dependent Claims (27, 28)
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29. A digital image processing method for determining orientation of faces located in a digital color image, comprising the steps of:
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generating a mean grid pattern element image from a plurality of sample face images; generating an integral image from the digital color image; locating a face in the color digital image by using the integral image to perform a correlation test between the mean grid pattern element 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 at different effective resolutions and correlating the mean grid pattern element image with the plurality of grid pattern element images, whereby either the mean grid pattern element image or the grid pattern element images are provided at a plurality of different orientations; and determining an orientation index of the face in the color digital image by using the images with different orientations in the correlation test of step c); repeating said generating, generating, locating, and determining steps to provide a plurality of faces; wherein said determining step further comprises the steps of; rank ordering the orientation indicies associated with the faces; determining the image orientation by applying an order statistics analysis to the rank ordered orientation indices associated with the faces; and determining the image orientation by voting using a top few of the orientation indices.
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Specification