Method and apparatus for image data transformation

Abstract

A method and apparatus for transforming image data by recursively interleaving the data to generate blocks of component image coefficients having form suitable for subsequent quantization, motion estimation, and/or coding. In preferred embodiments, the transformed data are in optimal form for coding by conventional circuitry in accordance with the conventional JPEG or MPEG compression algorithm. In preferred embodiments, the invention includes two memory arrays (each having capacity to store one or more N.times.M image data blocks), and an analyzer connected between the memory arrays. The analyzer receives horizontal vectors (such as full rows) of an image data block stored in the first memory, transforms each horizontal vector into two vectors (each comprising half as many words as the horizontal vector), interleaves the two vectors, and writes the resulting interleaved data (an orthogonal representation of the horizontal vector) into a row of the second memory. The analyzer then sequentially receives vertical vectors (such as columns) of an image data block stored in the second memory, converts each vertical vector into two vectors (each comprising half as many words as the vertical vector), interleaves the vectors, and writes the resulting interleaved data into a column of the first memory. Typically, multiple iterations are performed. After each iteration, the first memory contains a set of interleaved component image blocks. Preferably, the analyzer is a wavelet transform module including a pair of conjugate mirror filters and an interleaving circuit.