Feature extraction unit, feature extraction method, feature extraction program, and image processing device
View Patent ↗Provided is a feature extraction device whereby it is possible, while using local binary patterns, to extract image features with which object detection which is robust against disparities in a photographic environment is possible. A feature extraction unit ( 440 ) comprises: a binary pattern generation unit ( 443 ) which generates, for each of all pixels or partial pixels in an image, local binary patterns which denote, by bit values, whether the difference in pixel values between the pixel and the surrounding adjacent pixels is greater than or equal to a threshold value; a weighting generation unit ( 444 ) which determines, for each generated local binary pattern, a weighting according to the pixel value difference; and a histogram generation unit ( 445 ) which applies the determined weightings to the corresponding local binary patterns and generates a histogram which denotes the distribution of the local binary patterns which are generated from the image.
1. A feature extracting device comprising:
a binary pattern generating section that generates a local binary pattern for each of at least a plurality of first pixels in an image, the local binary pattern being represented by a set of bit values indicating whether differences in pixel values between a first pixel of the plurality of first pixels and surrounding second pixels are each equal to or greater than a predetermined threshold, the second pixels being at predetermined positions relative to the first pixel;
a weight generating section that determines a weight of each of the generated local binary patterns depending on the differences in pixel values between the first pixel and the second pixels; and
a histogram generating section that applies each determined weight to the corresponding local binary pattern to generate a histogram indicating a distribution of the local binary patterns generated from the image,
wherein each local binary pattern is a code having digital values arranged in a predetermined order, the digital values indicating whether each of the differences between the first pixel and the second pixels are equal to or greater than the predetermined threshold.
2. The feature extracting device according to claim 1 , wherein each weight depends on the sum of absolute values of the differences associated with the second pixels.
3. The feature extracting device according to claim 2 , wherein
the weight generating section determines the sum of the absolute values of each of the generated local binary patterns as a weight, and
each time a local binary pattern is generated, the histogram generating section adds the weight corresponding to the local binary pattern to a value of a bin corresponding to the local binary pattern to generate the histogram.
4. The feature extracting device according to claim 3 , wherein the histogram generating section normalizes the histogram.
5. An image processing apparatus comprising an identifying section that identifies a predetermined object using a classifier to determine whether an image includes the predetermined object on the basis of the histogram generated by the feature extracting device according to any one of claims 1 to 4 .
6. The image processing apparatus according to claim 5 , wherein
the classifier determines a noise level of the image on the basis of at least one of a bin value corresponding to the local binary pattern acquired if all the differences of the second pixels are positive values and a bin value corresponding to the local binary pattern acquired if all the differences of the second pixels are negative values.