Abstract: A method and device for transcoding digital images where at least portions of a first image coded according to a first method is decoded for obtaining first coefficients of a luminance component and chrominance components of the first image, where the chrominance components are subjected to a combined inverse quantization according to the first method and quantization according to a second method. The combined inverse quantization and quantization respectively uses a chrominance quantization matrix and a luminance quantization matrix for obtaining second coefficients for chrominance components of the second image having the same chroma format as the JPEG image. Finally, the first coefficients of the luminance component of the first image and the second coefficients of the chrominance components of the second image are coded for obtaining the second image decodable according to the second method.

Abstract: A microprocessor structure for performing a discrete wavelet transform operation, said discrete wavelet transform operation comprising decomposition of an input signal comprising a vector of r×km input samples, r, k and m being non-zero positive integers, over a specified number of decomposition levels j, where j is an integer in the range 1 to J, starting from a first decomposition level and progressing to a final decomposition level, said microprocessor structure having a number of processing stages, each of said number of processing stages corresponding to a decomposition level j of the discrete wavelet transform operation and being implemented by a number of basic processing elements, the number of basic processing elements implemented in each of said processing stages decreasing by a factor of k from a decomposition level j to a decomposition level j+1.

Abstract: A transcoder is provided for transcoding data comprising a group of macroblocks representing a frame of data, where the frame of data can include a plurality of sample lines each having a plurality of samples. The transcoder includes a decoder capable of decoding input data to thereby generate prediction error and decoded image data in the spatial domain. The transcoder also includes a downsampler capable of downsampling the prediction error or the decoded image data in a first (e.g., horizontal) direction and/or a second (e.g., vertical) direction different than the first direction to generate a downsampled macroblock in the spatial domain. In addition, the transcoder includes an encoder. The encoder, then, is capable of encoding the downsampled macroblock into output data.