A method of stereo image segmentation comprising: computing a stereo likelihood for each pixel in a first pair of stereo images in a sequence of pairs of stereo images; and performing image segmentation on the first pair of stereo images based on the computed stereo likelihood for each pixel (101, 203); and characterised in that the method further comprises: selecting an image from a second pair of stereo images in the sequence and determining based on an image from an immediately preceding pair of stereo images, for each pixel, if a change has occurred (102, 204) using an algorithm including one or more motion likelihoods for each pixel; for each pixel where a change has occurred, computing a stereo likelihood for the pixel in the second pair of stereo images; for each pixel where a change has not occurred, identifying a stereo likelihood for the pixel equal to the value of the stereo likelihood for the pixel in the immediately preceding pair of stereo images; and performing image segmentation on the second pair of stereo images based on the computed stereo likelihood for each pixel where a change has occurred and based on the identified stereo likelihood for each pixel where a change has not occurred (103, 208). computing a stereo likelihood for each pixel in a first pair of stereo images in a sequence of pairs of stereo images; and performing image segmentation on the first pair of stereo images based on the computed stereo likelihood for each pixel (101, 203); and characterised in that the method further comprises: selecting an image from a second pair of stereo images in the sequence and determining based on an image from an immediately preceding pair of stereo images, for each pixel, if a change has occurred (102, 204) using an algorithm including one or more motion likelihoods for each pixel; for each pixel where a change has occurred, computing a stereo likelihood for the pixel in the second pair of stereo images; for each pixel where a change has not occurred, identifying a stereo likelihood for the pixel equal to the value of the stereo likelihood for the pixel in the immediately preceding pair of stereo images; and performing image segmentation on the second pair of stereo images based on the computed stereo likelihood for each pixel where a change has occurred and based on the identified stereo likelihood for each pixel where a change has not occurred (103, 208). selecting an image from a second pair of stereo images in the sequence and determining based on an image from an immediately preceding pair of stereo images, for each pixel, if a change has occurred (102, 204) using an algorithm including one or more motion likelihoods for each pixel; for each pixel where a change has occurred, computing a stereo likelihood for the pixel in the second pair of stereo images; for each pixel where a change has not occurred, identifying a stereo likelihood for the pixel equal to the value of the stereo likelihood for the pixel in the immediately preceding pair of stereo images; and performing image segmentation on the second pair of stereo images based on the computed stereo likelihood for each pixel where a change has occurred and based on the identified stereo likelihood for each pixel where a change has not occurred (103, 208).