A method of processing a sequence of images of a scene, the method comprising: predefining a region of interest to be tracked, said region of interest comprising a portion of said scene; tracking said region of interest in the sequence of images; selecting a particular image in the sequence; selecting a set of images from the sequence, the set of images comprising a plurality of images that precede the particular image in the sequence of images; and determining a value indicative of the level of change between the region of interest in the particular image and the regions of interest in the images in the set of images; wherein: determining a value indicative of the level of change is implemented using a Change Detection Process; and the Change Detection Process comprises: for each pixel in the region of interest in the particular image, determining a value for the red-intensity, green-intensity and blue-intensity of a pixel; for each pixel in the region of interest of each image in the set of images, determining a value for the red-intensity, green-intensity and blue-intensity of each pixel; for the particular image, determining a histogram cube of the determined values for the region of interest in that image; for each of the images in the set of images, determining a histogram cube of the determined values for the region of interest in that image; determining a histogram cube that is a function of the histogram cubes determined for each of the images in the set of images; and determining a value of a parameter that is indicative of the difference between the histogram cube determined for the particular image and the histogram cube that is a function of the histogram cubes determined for each of the images in the set of images. predefining a region of interest to be tracked, said region of interest comprising a portion of said scene; tracking said region of interest in the sequence of images; selecting a particular image in the sequence; selecting a set of images from the sequence, the set of images comprising a plurality of images that precede the particular image in the sequence of images; and determining a value indicative of the level of change between the region of interest in the particular image and the regions of interest in the images in the set of images; wherein: determining a value indicative of the level of change is implemented using a Change Detection Process; and the Change Detection Process comprises: for each pixel in the region of interest in the particular image, determining a value for the red-intensity, green-intensity and blue-intensity of a pixel; for each pixel in the region of interest of each image in the set of images, determining a value for the red-intensity, green-intensity and blue-intensity of each pixel; for the particular image, determining a histogram cube of the determined values for the region of interest in that image; for each of the images in the set of images, determining a histogram cube of the determined values for the region of interest in that image; determining a histogram cube that is a function of the histogram cubes determined for each of the images in the set of images; and determining a value of a parameter that is indicative of the difference between the histogram cube determined for the particular image and the histogram cube that is a function of the histogram cubes determined for each of the images in the set of images. determining a value indicative of the level of change is implemented using a Change Detection Process; and the Change Detection Process comprises: for each pixel in the region of interest in the particular image, determining a value for the red-intensity, green-intensity and blue-intensity of a pixel; for each pixel in the region of interest of each image in the set of images, determining a value for the red-intensity, green-intensity and blue-intensity of each pixel; for the particular image, determining a histogram cube of the determined values for the region of interest in that image; for each of the images in the set of images, determining a histogram cube of the determined values for the region of interest in that image; determining a histogram cube that is a function of the histogram cubes determined for each of the images in the set of images; and determining a value of a parameter that is indicative of the difference between the histogram cube determined for the particular image and the histogram cube that is a function of the histogram cubes determined for each of the images in the set of images. for each pixel in the region of interest in the particular image, determining a value for the red-intensity, green-intensity and blue-intensity of a pixel; for each pixel in the region of interest of each image in the set of images, determining a value for the red-intensity, green-intensity and blue-intensity of each pixel; for the particular image, determining a histogram cube of the determined values for the region of interest in that image; for each of the images in the set of images, determining a histogram cube of the determined values for the region of interest in that image; determining a histogram cube that is a function of the histogram cubes determined for each of the images in the set of images; and determining a value of a parameter that is indicative of the difference between the histogram cube determined for the particular image and the histogram cube that is a function of the histogram cubes determined for each of the images in the set of images.