Efficient descriptor extraction over multiple levels of an image scale space
First Claim
1. A method for generating a local feature descriptor for an image, comprising:
- identifying a point within a first scale space from a plurality of scale spaces for an image;
obtaining a plurality of image derivatives for each of the plurality of scale spaces;
obtaining a plurality of orientation maps for each scale space in the plurality of scale spaces, where each of the plurality of orientation maps is obtained from non-negative values of a corresponding image derivative;
for each scale space in the plurality of scale spaces, smoothing each of the plurality of orientation maps to obtain a corresponding plurality of smoothed orientation maps; and
sparsely sampling a plurality of smoothed orientation maps corresponding to two or more scale spaces from the plurality of scale spaces to generate a local feature descriptor for the pointwherein each of the smoothed orientation maps that is sparsely sampled is derived using a different orientation map than each of the other smoothed orientation maps that is sparsely sampled.
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Abstract
A local feature descriptor for a point in an image is generated over multiple levels of an image scale space. The image is gradually smoothened to obtain a plurality of scale spaces. A point may be identified as the point of interest within a first scale space from the plurality of scale spaces. A plurality of image derivatives is obtained for each of the plurality of scale spaces. A plurality of orientation maps is obtained (from the plurality of image derivatives) for each scale space in the plurality of scale spaces. Each of the plurality of orientation maps is then smoothened (e.g., convolved) to obtain a corresponding plurality of smoothed orientation maps. Therefore, a local feature descriptor for the point may be generated by sparsely sampling a plurality of smoothed orientation maps corresponding to two or more scale spaces from the plurality of scale spaces.
30 Citations
37 Claims
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1. A method for generating a local feature descriptor for an image, comprising:
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identifying a point within a first scale space from a plurality of scale spaces for an image; obtaining a plurality of image derivatives for each of the plurality of scale spaces; obtaining a plurality of orientation maps for each scale space in the plurality of scale spaces, where each of the plurality of orientation maps is obtained from non-negative values of a corresponding image derivative; for each scale space in the plurality of scale spaces, smoothing each of the plurality of orientation maps to obtain a corresponding plurality of smoothed orientation maps; and sparsely sampling a plurality of smoothed orientation maps corresponding to two or more scale spaces from the plurality of scale spaces to generate a local feature descriptor for the point wherein each of the smoothed orientation maps that is sparsely sampled is derived using a different orientation map than each of the other smoothed orientation maps that is sparsely sampled. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 29, 30)
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14. An image processing device, comprising:
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an input interface adapted to obtain an image; a storage device to store local feature descriptors for one or more images; a hardware processing circuit coupled to the input interface and the storage device, the hardware processing circuit adapted to; identify a point within a first scale space from a plurality of scale spaces for an image; obtain a plurality of image derivatives for each of the plurality of scale spaces; obtain a plurality of orientation maps for each scale space in the plurality of scale spaces, where each of the plurality of orientation maps is obtained from non-negative values of a corresponding image derivative; for each scale space in the plurality of scale spaces, smooth each of the plurality of orientation maps to obtain a corresponding plurality of smoothed orientation maps; and sparsely sample a plurality of smoothed orientation maps corresponding to two or more scale spaces from the plurality of scale spaces to generate a local feature descriptor for the point, wherein each of the smoothed orientation maps that is sparsely sampled is derived using a different orientation map than each of the other smoothed orientation maps that is sparsely sampled. - View Dependent Claims (15, 16, 17, 18, 19, 20, 32, 33)
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21. An image processing device, comprising:
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means for identifying a point within a first scale space from a plurality of scale spaces for an image; means for obtaining a plurality of image derivatives for each of the plurality of scale spaces; means for obtaining a plurality of orientation maps for each scale space in the plurality of scale spaces, where each of the plurality of orientation maps is obtained from non-negative values of a corresponding image derivative; means for smoothing, for each scale space in the plurality of scale spaces, each of the plurality of orientation maps to obtain a corresponding plurality of smoothed orientation maps; and means for sparsely sampling a plurality of smoothed orientation maps corresponding to two or more scale spaces from the plurality of scale spaces to generate a local feature descriptor for the point, wherein each of the smoothed orientation maps that is sparsely sampled is derived using a different orientation map than each of the other smoothed orientation maps that is sparsely sampled. - View Dependent Claims (22, 23, 24, 25, 26, 34, 35, 36)
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27. A non-transitory processor-readable medium comprising one or more instructions operational in a device, which when executed by a processing circuit, causes the processing circuit to:
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identify a point within a first scale space from a plurality of scale spaces for an image; obtain a plurality of image derivatives for each of the plurality of scale spaces; obtain a plurality of orientation maps for each scale space in the plurality of scale spaces, where each of the plurality of orientation maps is obtained from non-negative values of a corresponding image derivative; for each scale space in the plurality of scale spaces, smooth each of the plurality of orientation maps to obtain a corresponding plurality of smoothed orientation maps; and sparsely sample a plurality of smoothed orientation maps corresponding to two or more scale spaces from the plurality of scale spaces to generate a local feature descriptor for the point, wherein each of the smoothed orientation maps that is sparsely sampled is derived using a different orientation map than each of the other smoothed orientation maps that is sparsely sampled. - View Dependent Claims (28, 31, 37)
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Specification