VISUAL SALIENCY ESTIMATION FOR IMAGES AND VIDEO

• US 20150227810A1
• Filed: 04/22/2015
• Published: 08/13/2015
• Est. Priority Date: 08/29/2012
• Status: Active Grant

• Current Assignee: Disney Enterprises Incorporated (The Walt Disney Company)
• Original Assignee: Disney Enterprises Incorporated (The Walt Disney Company)
• Inventors: Perazzi, Federico, Hornung, Alexander, Krhenbhl, Philipp, Pritch, Yael
• Granted Patent: US 9,483,709 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 18/22 Matching criteria, e.g. proximity measures
• CPC Class Codes: G06T 2207/10004 Still image; Photographic image
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/194 involving foreground-background segmentation
• CPC Class Codes: G06T 7/246 using feature-based methods, e.g. the tracking of corners or segments
• CPC Class Codes: G06T 7/44 using image operators, e.g. filters, edge density metrics or local histograms
• CPC Class Codes: G06T 7/90 Determination of colour characteristics
• CPC Class Codes: G06V 10/462 Salient features, e.g. scale invariant feature transforms [SIFT]
• CPC Class Codes: G06V 10/56 relating to colour
• CPC Class Codes: G06V 10/758 Involving statistics of pixels or of feature values, e.g. histogram matching
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635

Abstract

Methods and apparatus for deriving a saliency measure for images and video are described. In an embodiment, a process includes decomposing, by a processor, an image into elements, wherein elements cluster the image and each element consists of spatially connected pixels. The processor then calculates a first image measure indicative of each element'"'"'s uniqueness in the image on a per element basis, and calculates a second image measure indicative of each element'"'"'s spatial distribution in the image on a per element basis. The processor then provides a per element saliency measure by combining the first image measure and the second image measure.

Claims

1. A method for deriving a saliency measure, comprising:

decomposing, by a processor, an image into elements, wherein elements cluster the image and each element consists of spatially connected pixels;

calculating, by the processor, a first image measure indicative of each element'"'"'s uniqueness in the image on a per element basis;

calculating, by the processor, a second image measure indicative of each element'"'"'s spatial distribution in the image on a per element basis; and

providing, by the processor, a per element saliency measure by combining the first image measure and the second image measure.

2. The method of claim 1, further comprising generating, by the processor based on the per element saliency measure, a pixel-accurate image saliency map.

3. The method of claim 2, wherein generating the pixel accurate saliency map comprises utilizing an up-sampling process that is both local and feature sensitive.

4. The method of claim 1, wherein at least one of the first image measure and the second image measure is calculated based on at least one discriminating feature extracted from the pixels associated with each element.

5. The method of claim 4, wherein the discriminating feature comprises at least one of a color feature, a texture feature, a disparity feature, and a motion feature.

6. The method of claim 1, wherein decomposing comprises utilizing, by the processor, a modified simple linear iterative clustering (SLIC) superpixels protocol that utilizes K-means clustering in geodesic image distance in CEILab space.

7. The method of claim 1, wherein at least one of the calculating of the first image measure and the calculating of the second image measure comprises utilizing Gaussian filtering.

8. The method of claim 1, wherein combining the first image measure and the second image measure comprises:

normalizing uniqueness measures and distribution measures to a range; and

combining each normalized uniqueness measure with a corresponding distribution measure to obtain the per element saliency measure.

9. The method of claim 1, wherein the image is a video frame image and wherein at least one of the first image measure and the second image measure is calculated based on a motion feature.

10. The method of claim 9, wherein the motion feature is based on an optical flow, and wherein the optical flow is computed by:

identifying, by the processor based on the per element saliency measure, a background portion of the video frame image;

computing, by the processor based on the identified background portion, a global transformation that aligns the video frame image with an adjacent video frame image; and

computing, by the processor, the optical flow based on the global transformation.

11. A non-transitory computer-readable medium storing instructions for deriving a saliency measure configured to cause a processor to:

decompose an image into elements, wherein elements cluster the image and each element consists of spatially connected pixels;

calculate a first image measure indicative of each element'"'"'s uniqueness in the image on a per element basis;

calculate a second image measure indicative of each element'"'"'s spatial distribution in the image on a per element basis; and

provide a per element saliency measure by combining the first image measure and the second image measure.

12. The computer-readable medium of claim 11, further comprising instructions configured to cause the processor to generate, based on the per element saliency measure, a pixel-accurate image saliency map.

13. The computer-readable medium of claim 12, wherein the instructions for generating the pixel accurate saliency map further comprise instructions configured to cause the processor to utilize an up-sampling process that is both local and feature sensitive.

14. The computer-readable medium of claim 11, wherein the instructions for calculating the first image measure or the second image measure further comprise instructions configured to cause the processor to calculate the first image measure or the second image measure based on at least one discriminating feature extracted from the pixels associated with each element.

15. The computer-readable medium of claim 11, wherein the instructions for decomposing further comprise instructions configured to cause the processor to utilize a modified simple linear iterative clustering (SLIC) superpixels protocol that utilizes K-means clustering in geodesic image distance in CEILab space.

16. The computer-readable medium of claim 11, wherein the instructions for calculating the first and second image measures further comprise instructions configured to cause the processor to utilize Gaussian filtering.

17. The computer-readable medium of claim 11, wherein the instructions for combining the first and second image measures further comprise instructions configured to cause the processor to:

normalize uniqueness measures and distribution measures to a range; and

combine each normalized uniqueness measure with a corresponding distribution measure to obtain the per element saliency measure.

18. The computer-readable medium of claim 11, wherein the image is a video frame image and the instructions for calculating at least one of the first image measure and the second image measure further comprises instructions configured to cause the processor to utilize a motion feature.

19. The computer-readable medium of claim 18, wherein the motion feature is based on an optical flow, and further comprising instructions for computing the optical flow that cause the processor to:

identify a background portion of the video frame image based on the per element saliency measure;

compute, based on the identified background portion, a global transformation that aligns the video frame image with an adjacent video frame image;

compute the optical flow based on the global transformation.

20. An apparatus for deriving a saliency measure, comprising:

a processor;

a communication device operably connected to the processor; and

a storage device operably connected to the storage device, the storage device storing non-transitory instructions configured to cause the processor to;

decompose an image into elements, wherein elements cluster the image and each element consists of spatially connected pixels;

calculate a first image measure indicative of each element'"'"'s uniqueness in the image on a per element basis;

calculate a second image measure indicative of each element'"'"'s spatial distribution in the image on a per element basis; and

provide a per element saliency measure by combining the first image measure and the second image measure.

21. The apparatus of claim 20, wherein the image is a video frame image, and wherein the instructions for calculating at least one of the first image measure and the second image measure stored in the storage device further comprises instructions configured to cause the processor to utilize a motion feature.

22. The apparatus of claim 21, wherein the motion feature is based on an optical flow, and wherein the storage device further comprises instructions for computing the optical flow that cause the processor to:

identify a background portion of the video frame image based on the per element saliency measure;

compute, based on the identified background portion, a global transformation that aligns the video frame image with an adjacent video frame image; and

compute the optical flow based on the global transformation.