Abstract: The invention provides an optical mask (1) for use in blending overlapping tiled images, the optical mask comprising a base (2); an array of elongate sliding elements (10) arranged side by side on the support, each sliding element being independently slidable along an axis and being constrained against lateral translational movement; the mask having a transmission-modifying edge (22) for positioning in a beam of light to modify transmission of the light, the transmission-modifying edge (22) having a profile which is adjustable by moving one or more of the sliding elements (10) along their axes.

Abstract: The invention provides an optical mask (1) for use in blending overlapping tiled images, the optical mask comprising a base (2); an array of elongate sliding elements (10) arranged side by side on the support, each sliding element being independently slidable along an axis and being constrained against lateral translational movement; the mask having a transmission-modifying edge (22) for positioning in a beam of light to modify transmission of the light, the transmission-modifying edge (22) having a profile which is adjustable by moving one or more of the sliding elements (10) along their axes.

Abstract: Methods of spatial compression of image data using trees formed with logic gates are described. Data encoding is achieved using a five-level wavelet transform, such as the Haar or 2/10 transforms. A dual transform engine is used, the first engine being used for the first and second parts of the first-level transform, and the subsequent-level transforms being performed by the second engine within a time not more than that taken by the first transform engine to effect the part-transform. Each bit plane of the resulting coefficients is then encoded by forming a tree structure from the bits and logical OR combinations thereof. Redundant data are removed. Further data can be removed with a predetermined compression profile. The resulting blocks of compressed data are of variable length and are packaged with sync and index words for transmission so that the location and identity of the transformed data blocks can be determined.

Abstract: A method and apparatus for resizing a digital video image composed of a plurality of source pixels which are resized to a plurality of target pixels using a technique which comprises: expressing the point brightness energy associated with each source pixel as an area which spans two source pixel intervals, each said area span having a shape which is proportional to the energy distribution of the source pixel with time; creating for each target pixel a sample aperture of duration which is a function of the resizing factor, sampling the area spans with each sample aperture to provide, for each target pixel, a set of coefficients, each coefficient representing the proportion of an area span which is within the sample aperture; and scaling, with its associated coefficient, the amount of point brightness energy of each source pixel whose area span appears within any given sample aperture.