Abstract: In a method of transforming an input data block (IDB) comprising frequency coefficients (CF) into an output data block (ODB) comprising spatial coefficients, the following steps are carried out. For each frequency coefficient (CF) which is not zero, an individual block of spatial coefficients (IB) is established on the basis of pre-stored data (PSD). The pre-stored data (PSD) pertains to a spatial pattern associated to the frequency coefficient (CF). The thus obtained individual blocks of spatial coefficients (IB) are accumulated to obtain the output data block (ODB). The method allows a transformation of the inverse-fourier type, such as an inverse discrete-cosine transformation for example, to be carried out with relatively little computational effort. The method is particularly suitable for use in video decoding applications.

Abstract: A method and device for reducing the average number of computations required for inverse discrete cosine transform by gathering block statistics during inverse quantization and inverse scan. These statistics include the location and frequency of sub-blocks containing non-zero, DC coefficients, the location of rows and columns that contain non-zero DCT coefficients, the dynamic range of the block, etc.

Abstract: Apparatus for converting a digital video signal between two different formats, such as interlaced field and non-interlaced progressive frame, and which avoids filtering and sub-sampling of portions of the video data which are the same in either format. For conversion from interlaced field to progressive frame, only alternate fields of the signal are subjected to digital filtering. The filtered fields are then combined with the non-filtered fields, which are subjected only to an equivalent delay, to derive averaged frames which constitute a progressive frame video signal. For the reverse conversion, alternate scan lines of each frame are sub-sampled and averaged to derive a field which is then interlaced with a field formed by the remaining scan lines of such frame, thereby deriving an interlaced field video signal.

Abstract: A method and apparatus for generating and receiving a high definition television signal suitable for use in a broadcasting environment wherein a conventional television signal is also used, having multiple frequency multiplexed subcarriers placed within the frequency spectrum of the signal so as to minimize interference with and from the conventional television signal.