Abstract: Interframe compression of moving image data is achieved by a combination of vector coding and scalar coding of transform coefficient differences formed by the subtraction of previous image transform coefficients from corresponding present image transform coefficients along a Zig-Zag path in the arrays of coefficients. More efficient scalar codes are used instead of vector codes for transmission of coefficient data where the previous image coefficients are non-zero along the path. Vector codes are used where a non-zero value in the previous image transform array has not been established but a non-zero value coefficient occurs in the present image transform array. Vector coding efficiency is improved by modified run length coding.

Abstract: A companding technique takes advantage of spatial masking in order to avoid problems from noise and/or distortion introduced when storing or transmitting video signals. A forward companding or encoding part of the technique divides a video frame into separate portions. A local average is calculated for each portion. For each pixel or picture element within a portion, the average of that portion is subtracted and the result is subjected to a non-linear forward process which emphasizes those video signals which are close to the local average and which de-emphasizes those video signal portions which are relatively different from the local average. An encoded output is applied to a medium and, upon recovery from the medium, the recovered signal is subjected to a decode process including a non-linear reconstruction process which is the inverse of the non-linear process applied at the encode stage.

Abstract: Disclosed are methods and apparatus for prioritization of transform domain coefficient data representing sources such as, but not limited to, single images and images in motion, so as to produce a data rate not exceeding the capacity of the transmission channel used in transmitting the data to a receiver and to simultaneously minimize the perceived distortion when the image is reconstructed at the receiver. One disclosed aspect relates in particular to transmission of Pyramid Transform coefficients from a single image over a fixed data rate transmission channel. In effect a sequence of multiple image reconstructions is performed at the receiver during the time period required for the transmission of all of the coefficient data representing the image. The reconstructed image gradually increases in detail.

Abstract: Transform techniques for transforming numerical signal data into a transform domain and subsequent reconstruction, for purposes such as compression (bandwidth reduction) for communication or storage. The subject transforms involve several defined basis functions which operate on input data points. The basis functions of the invention are essentially weighting functions such that terms and coefficients (in the transform domain) calculated in accordance with the basis functions are each a particularly weighted average of the values of a selected consecutive plurality of input data points. An important basis function is a triangular weighting function. Successive terms and coefficients generated in accordance with each of the defined basis functions are calculated from successive consecutive pluralities of the input data points, with overlap of input data points depending on the particular basis function. The transforms are organized into a plurality of bands or levels N.