Face detection in mid-shot digital images
View Patent ↗A method for detecting a face in a mid-shot digital image of a person comprises capturing first and second mid-shot digital images of nominally the same scene using different capture settings such that the foreground is differently differentiated from the background in each image, and comparing the first and second images to determine the foreground region of the images. A portion of the foreground region likely to correspond to a face is estimated based upon the geometry of the foreground region.
1. A method for detecting a face in a mid-shot digital image of a person, the method comprising:
using a lens, image sensor and processor of a digital image acquisition and processing apparatus,
capturing first and second mid-shot digital images of approximately a same scene that is known to include at least a face and a portion of a torso of a human person, including using different capture settings such that the foreground is differently differentiated from the background in each image,
comparing the first and second images to determine the foreground region of the images, and
identifying a portion of the foreground region likely to correspond to a face based upon matching one or more known face-to-torso geometric relationships to one or more geometric relationships between regions of the foreground region of the first and second images.
2. The method of claim 1 , wherein the different capture settings comprise taking one image using a flash and taking the other image without using a flash.
3. The method of claim 1 , wherein the different capture settings comprise taking one image with the foreground more in focus than the background and taking the other image with the background more in focus than the foreground.
4. The method of claim 1 , wherein the first and second images have different pixel resolutions.
5. The method of claim 4 , further comprising matching the pixel resolutions of the first and second images prior to the comparing.
6. The method of claim 1 , wherein the first and second images are captured by a digital camera.
7. The method of claim 6 , wherein the first image is a relatively high resolution main image, and wherein the second image is a relatively low resolution pre- or post-view version of the first image.
8. The method of claim 6 , wherein the first and second images are relatively low resolution pre- and/or post-view versions of a higher resolution main image of said scene also captured by the camera.
9. A digital image acquisition and processing apparatus comprising:
means for capturing first and second mid-shot digital images of approximately a same scene that is known to include at least a face and a portion of a torso of a human person, including using different capture settings such that the foreground is differently differentiated from the background in each image,
means for comparing the first and second images to determine the foreground region of the images, and
means for identifying a portion of the foreground region likely to correspond to a face based upon matching one or more known face-to-torso geometric relationships to one or more geometric relationships between regions of the foreground region of the first and second images.
10. One or more non-transitory processor-readable media having code embedded therein for programming a processor to perform a method for detecting a face in a mid-shot digital image of a person, wherein the method comprises:
using a lens, image sensor and processor of a digital image acquisition and processing apparatus,
capturing first and second mid-shot digital images of approximately a same scene that is known to include at least a face and a portion of a torso of a human person, including using different capture settings such that the foreground is differently differentiated from the background in each image,
comparing the first and second images to determine the foreground region of the images, and
identifying a portion of the foreground region likely to correspond to a face based upon matching one or more known face-to-torso geometric relationships to one or more geometric relationships between regions of the foreground region of the first and second images.
11. The one or more processor-readable media of claim 10 , wherein the different capture settings comprise taking one image using a flash and taking the other image without using a flash.
12. The one or more processor-readable media of claim 10 , wherein the different capture settings comprise taking one image with the foreground more in focus than the background and taking the other image with the background more in focus than the foreground.
13. The one or more processor-readable media of claim 10 , wherein the first and second images have different pixel resolutions.
14. The one or more processor-readable media of claim 13 , wherein the method further comprises matching the pixel resolutions of the first and second images prior to the comparing.
15. The one or more processor-readable media of claim 10 , wherein the first and second images are captured by a digital camera.
16. The one or more processor-readable media of claim 15 , wherein the first image is a relatively high resolution main image, and wherein the second image is a relatively low resolution pre- or post-view version of the first image.
17. The one or more processor-readable media of claim 15 , wherein the first and second images are relatively low resolution pre- and/or post-view versions of a higher resolution main image of said scene also captured by the camera.
18. A digital image acquisition and processing apparatus, comprising:
a lens;
an image sensor;
a processor; and
a processor-readable medium having code embedded therein for programming the processor to perform a method for detecting a face in a mid-shot digital image of a person, wherein the method comprises:
capturing first and second mid-shot digital images of approximately a same scene that is known to include at least a face and a portion of a torso of a human person, including using different capture settings such that the foreground is differently differentiated from the background in each image,
comparing the first and second images to determine the foreground region of the images, and
identifying a portion of the foreground region likely to correspond to a face based upon matching one or more known face-to-torso geometric relationships to one or more geometric relationships between regions of the foreground region of the first and second images.
19. The apparatus of claim 18 , wherein the different capture settings comprise taking one image using a flash and taking the other image without using a flash.
20. The apparatus of claim 18 , wherein the different capture settings comprise taking one image with the foreground more in focus than the background and taking the other image with the background more in focus than the foreground.
21. The apparatus of claim 18 , wherein the first and second images have different pixel resolutions.
22. The apparatus of claim 21 , wherein the method further comprises matching the pixel resolutions of the first and second images prior to the comparing.
23. The apparatus of claim 18 , wherein the first and second images are captured by a digital camera.
24. The apparatus of claim 23 , wherein the first image is a relatively high resolution main image, and wherein the second image is a relatively low resolution pre- or post-view version of the first image.
25. The apparatus of claim 23 , wherein the first and second images are relatively low resolution pre- and/or post-view versions of a higher resolution main image of said scene also captured by the camera.