Apple Inc.

Marvell Israel (misl) Ltd.

Assaf Metuki

Liran Fishel

Muge Wang

David R Pope

Danny Gal

Wai Yu Trevor Tsang

Chuhan Min

Lukas Polok

Embodiments relate to generating keypoint descriptors of the keypoints. An apparatus includes a pyramid image generator circuit and a keypoint descriptor generator circuit. The pyramid image generator circuit generates an image pyramid from an input image. The keypoint descriptor generator circuit determines intensity values of sample points in the pyramid images for a keypoint and determines comparison results of comparisons between the intensity values of pairs of the sample points. The keypoint descriptor generator circuit generate bit values defining the comparison results for the keypoint, each bit value corresponding with one of the comparison results, and generate a sequence of the bit values defining an ordering of the comparison results based on importance levels of the comparisons, where the importance level of each comparison defines how much the comparison is representative of features. Bit values for comparisons having the lowest importance levels may be excluded from the sequence.

Configurable keypoint descriptor generation

Embodiments of the present disclosure relate to sequentially loading keypoint descriptors of a previous image and comparing them with a plurality of keypoint descriptors of a current image. The keypoint descriptors of the previous image are stored and accessed from a system memory while the keypoint descriptors of the current image are stored and accessed from a local memory. Hence, the keypoint descriptors of the previous image are received only once at a descriptor match circuit while the keypoint descriptors of the current image are received multiple times for comparison against different keypoint descriptors of the previous image.

Single read of keypoint descriptors of image from system memory for efficient header matching

Embodiments of the present disclosure relate to selecting a subset of keypoint descriptors of two images for match operation based on their orientation angles indicated in headers of the keypoint descriptors. The keypoint descriptors in the two images are matched by first comparing their headers and then performing vector distance determination. During the header comparison operation, a header of a descriptor of a first image is compared only with headers of keypoint descriptors of a second image in a discrete orientation angle range corresponding to an orientation angle indicated by the header of the first image descriptor or keypoint descriptors of the second image in adjacent discrete orientation angle ranges. After the headers of the keypoint descriptors satisfying one or more matching criteria are determined, distance determination operations are performed between the keypoint descriptors while the remaining keypoint descriptors are discarded without determining their distances.

Filtering of keypoint descriptors based on orientation angle

Embodiments relate to extracting features from images, such as by identifying keypoints and generating keypoint descriptors of the keypoints. An apparatus includes a pyramid image generator circuit, a keypoint descriptor generator circuit, and a pyramid image buffer. The pyramid image generator circuit generates an image pyramid from an input image. The keypoint descriptor generator circuit processes the pyramid images for keypoint descriptor generation. The pyramid image buffer stores different portions of the pyramid images generated by the pyramid image generator circuit at different times and provides the stored portions of the pyramid images to the keypoint descriptor generator circuit for keypoint descriptor generation. When first portions of the pyramid images are no longer needed for the keypoint descriptor generation, the first portions are removed from the pyramid image buffer to provide space for second portions of the pyramid images that are needed for the keypoint descriptor generation.

Sliding window for image keypoint detection and descriptor generation

Embodiments relate to generating keypoint descriptors of the keypoints using a sub-scale refinement and a sample pattern radius adjustment. An apparatus includes a sub-pixel refiner circuit and a keypoint descriptor generator circuit. The sub-pixel refiner circuit determines a keypoint scale value for a scale dimension of a keypoint in an image pyramid by performing an interpolation of response map (RM) pixel values of a pixel block of RM images defined around the keypoint. The keypoint descriptor generator circuit determines sample scales of the image pyramid based on the keypoint scale value and determines a radius value for each sample scale based on the keypoint scale value. The keypoint descriptor generator circuit samples patches of pixel values at the sample scales using the radius value for each sample scale to generate a keypoint descriptor of the keypoint.

Pattern radius adjustment for keypoint descriptor generation

Embodiments relate to generating an image pyramid for feature extraction. A pyramid image generator circuit includes a first image buffer that stores image data at a first octave, a first blur filter circuit, a first spatial filter circuit, and a first decimator circuit. The first blur filter circuit generates a first pyramid image for a first scale of the first octave by applying a first amount of smoothing to the first image data stored in the first image buffer. The first spatial filter circuit and the first decimator generate second image data of a second octave that is higher than the first octave by applying a smoothing and a decimation to the first image data stored in the first image buffer. The first spatial filter circuit begins processing the first image data before the first blur filter circuit begins to process the first image data.

Image pyramid generation for image keypoint detection and descriptor generation

Some of the embodiments of the present disclosure provide a method including receiving data to be stored in a memory, the data including (i) data bits and (ii) a tag indicating that one or more of the data bits are corrupted; generating eight error correction code (ECC) bits corresponding to the data bits of the data; in response to the data including the tag indicating that one or more of the data bits are corrupted, modifying seven bits of the eight ECC bits to generate modified ECC bits, wherein the seven bits of the eight ECC bits are modified to indicate that one or more of the corresponding data bits are corrupted; and writing the data bits, along with the modified ECC bits, to the memory. Other embodiments are also described and claimed.

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Moshav Herut, Israel

Assaf Metuki