Method, system, and computer readable medium for face detection
View Patent ↗A method, system, and computer readable medium for detecting a face in a video stream including receiving a sequence of input color images; and for each input image, calculating a greyscale image of the input color image, creating a one-bit motion image based on the current and a previous greyscale image, calculating a normalized color image of the input color image, calculating a motion color probability image, providing at least the grayscale image and the motion color probability image to a face detector, and executing face detection by determining a presence of a face based on first features in the grayscale image and second features in the motion color probability image.
1. A method for detecting a face in a video stream comprising:
receiving, at a video processing apparatus, a sequence of input color images; and
for each input image, processing the sequence at the video processing apparatus, wherein the process includes,
calculating a greyscale image of the input color image,
creating a one-bit motion image based on the current greyscale image and a previous greyscale image,
calculating a normalized color image of the input color image,
calculating a motion color probability image by,
calculating a first color histogram of the pixels in the normalized image,
calculating a second color histogram of the pixels in the normalized image corresponding to pixels in the motion image defined as being in motion,
calculating a ratio histogram by dividing the first color histogram by the second color histogram, and
setting pixel values in the motion color probability image to a value obtained by indexing the ratio histogram using values from the original normalized image,
providing at least the grayscale image and the motion color probability image to a face detector, and
executing face detection by determining a presence of a face based on first features in the grayscale image and second features in the motion color probability image.
2. The method according to claim 1 , wherein the first features include geometrical features or patterns.
3. The method according to claim 1 , wherein the second features include intensity information, the intensity information defining the presence or non-presence of assumed skin colors.
4. The method according to claim 1 , further comprising:
providing the motion image to the face detector, wherein the presence of a face is further based on third features in the motion image.
5. The method according to claim 1 , wherein the input color image is in the RGB color space, and wherein the normalized image is created by converting a copy of the input color image to the RG chromaticity space.
6. The method according to claim 1 , wherein when the face detector detects a face in one of the input images, the calculating of the motion color probability image extracts the location of the detected face and calculates a second color histogram of the pixels representing the detected face.
7. The method according to claim 1 , wherein the receiving of the sequence of input color images is received from a static video camera.
8. An apparatus for detecting a face in a video stream comprising:
a video processor that receives a sequence of input color images; and
for each input image, the video processor,
calculates a greyscale image of the input color image,
creates a one-bit motion image based on the current greyscale image and a previous greyscale image,
calculates a normalized color image of the input color image,
calculates a motion color probability image, wherein the video processor further,
calculates a first color histogram of the pixels in the normalized image,
calculates a second color histogram of the pixels in the normalized image corresponding to pixels in the motion image defined as being in motion,
calculates a ratio histogram by dividing the first color histogram by the second color histogram, and
sets pixel values in the motion color probability image to a value obtained by indexing the ratio histogram using values from the original normalized image,
provides at least the grayscale image and the motion color probability image to a face detector, and
executes face detection by determining a presence of a face based on first features in the grayscale image and second features in the motion color probability image.
9. The apparatus according to claim 8 , wherein the first features include geometrical features or patterns.
10. The apparatus according to claim 8 , wherein the second features include intensity information, the intensity information defining the presence or non-presence of is assumed skin colors.
11. The apparatus according to claim 8 , wherein the video processor further provides the motion image to the face detector, and wherein the presence of a face is further based on third features in the motion image.
12. The apparatus according to claim 8 , wherein the input color image is in the RGB color space, and wherein the normalized image is created by converting a copy of the input color image to the RG chromaticity space.
13. The apparatus according to claim 8 , wherein when the face detector detects a face in one of the input images, the video processor extracts the location of the detected face and calculates a second color histogram of the pixels representing the detected face.
14. The apparatus according to claim 8 , wherein the video processor receives the sequence of input color images from a static video camera.
15. A non-transitory computer readable storage medium encoded with computer executable instructions, wherein the instructions, when executed by a video processing apparatus, cause the video processing apparatus to perform a method for detecting a face in a video stream, the method comprising:
receiving, at the video processing apparatus, a sequence of input color images; and
for each input image, processing the sequence at the video processing apparatus, wherein the process includes,
calculating a greyscale image of the input color image,
creating a one-bit motion image based on the current greyscale image and a previous greyscale image,
calculating a normalized color image of the input color image,
calculating a motion color probability image by,
calculating a first color histogram of all the pixels in the normalized image,
calculating a second color histogram of the pixels in the normalized image corresponding to pixels in the motion image defined as being in motion,
calculating a ratio histogram by dividing the first color histogram by the second color histogram, and
setting pixel values in the motion color probability image to a value obtained by indexing the ratio histogram using values from the original normalized image,
providing at least the grayscale image and the motion color probability image to a face detector, and
executing face detection by determining a presence of a face based on first features in the grayscale image and second features in the motion color probability image.
16. The computer readable medium according to claim 15 , wherein the first features include geometrical features or patterns.
17. The computer readable medium according to claim 15 , wherein the second features include intensity information, the intensity information defining the presence or non-presence of assumed skin colors.
18. The computer readable medium according to claim 15 , further comprising:
providing the motion image to the face detector, wherein the presence of a face is further based on third features in the motion image.
19. The computer readable medium according to claim 15 , wherein the input color image is in the RGB color space, and wherein the normalized image is created by converting a copy of the input color image to the RG chromaticity space.
20. The computer readable medium according to claim 15 , wherein when the face detector detects a face in one of the input images, the calculating of the motion color probability image extracts the location of the detected face and calculates a second color histogram of the pixels representing the detected face.