Analysis of 3D video
An image analysis apparatus for processing a 3D video signal comprising successive pairs of images representing different respective views of a scene to generate an image depth indicator comprises a correlator configured to correlate image areas in one of the pair of images with image areas in the other of the pair of images so as to detect displacements of corresponding image areas between the two images; a graphics generator configured to generate a graphical representation of the distribution of the displacements, with respect to a range of possible displacement values, across the pair of images; and a display generator for generating for display the graphical representation in respect of a current pair of images and in respect of a plurality of preceding pairs of images, so as to provide a time-based representation of variations in the distribution of the displacements.
1. An image analysis apparatus for processing an image to generate an image focus indicator, the apparatus comprising:
a focus detector configured to detect respective local focus estimates for a plurality of blocks of the image, and to combine the local focus estimates to generate the image focus indicator for that image, wherein
the focus detector is configured to detect the local focus estimates by detecting image contrast in a group of pixels around the respective block,
the group of pixels comprises a square array of pixels centred around the respective block,
the focus detector is configured to detect image contrast in a group by detecting the difference between the maximum pixel brightness and the minimum pixel brightness in that group,
the image is an image of a 3D pair of images representing different respective views of a scene,
the focus detector is configured to detect the image focus indicator in respect of each image of the pair,
the image analysis apparatus is configured to compare the image focus indicators in respect of the pair of images, to detect whether the pair of images have a similar degree of focus, and
the focus detector is configured to detect differences between local focus estimates of corresponding areas of the pair of images.
2. Apparatus according to claim 1 , in which each block comprises a respective single pixel of the image.
3. Apparatus according to claim 1 , in which the apparatus is responsive to displacement data indicating displacements between image features in the pair of images, the focus detector being configured to apply the displacement data in the selection of corresponding areas of the pair of images.
4. An image analysis method for processing an image to generate an image focus indicator, the method comprising:
detecting respective local focus estimates for a plurality of blocks of the image; and
combining the local focus estimates to generate the image focus indicator for that image, wherein
the detecting includes detecting the local focus estimates by detecting image contrast in a group of pixels around the respective block,
the group of pixels comprises a square array of pixels centred around the respective block,
the detecting includes detecting image contrast in a group by detecting the difference between the maximum pixel brightness and the minimum pixel brightness in that group,
the image is an image of a 3D pair of images representing different respective views of a scene,
the detecting includes detecting the image focus indicator in respect of each image of the pair,
the method further comprising comparing the image focus indicators in respect of the pair of images, to detect whether the pair of images have a similar degree of focus, and
the detecting includes detecting differences between local focus estimates of corresponding areas of the pair of images.
5. A computer program product comprising a non-transitory machine-readable storage medium on which computer software is stored, which software, when executed by a computer, causes the computer to carry out an image analysis method for processing an image to generate an image focus indicator, the method comprising:
detecting respective local focus estimates for a plurality of blocks of the image; and
combining the local focus estimates to generate the image focus indicator for that image, wherein
the detecting includes detecting the local focus estimates by detecting image contrast in a group of pixels around the respective block,
the group of pixels comprises a square array of pixels centred around the respective block,
the detecting includes detecting image contrast in a group by detecting the difference between the maximum pixel brightness and the minimum pixel brightness in that group,
the image is an image of a 3D pair of images representing different respective views of a scene,
the detecting includes detecting the focus indicator in respect of each image of the pair,
the method further comprising comparing the focus indicators in respect of the pair of images, to detect whether the pair of images have a similar degree of focus, and
the detecting includes detecting differences between local focus estimates of corresponding areas of the pair of images.