Transformed coefficient ordering for entropy coding

An encoder that, when in operation, encodes input data to generate corresponding encoded output data,

• wherein the encoder converts input data into base-layer reconstruction data using a down-sampled version of the input data,
• wherein the encoder generates enhancement-layer data that provides instructions for enhancing the down-sampled version of the input data,
• wherein the enhancement-layer data comprises residual data that represents a difference between a reconstruction generated from the base-layer reconstruction data and data derived from the input data,
• wherein the residual data are subjected in the encoder to a Hadamard transform to convert the residual data to corresponding Hadamard transform coefficients,
• wherein different output elements of the Hadamard transform are arranged as different surfaces to be encoded, each surface corresponding to a respective directional component of the transform, and wherein an output order traverses transform coefficients across multiple ones of the surfaces,
• wherein the encoder is configured to select an output order for the transform coefficients in the surfaces to provide an ordered sequence of transform coefficients for at least one data compression method,
• wherein the selected output order is one of a tile raster order and an n-by-n block “Z”-order, and wherein the selected output order operates over groups of coefficients spanning multiple surfaces and multiple coding units and is chosen based on content-dependent spatial-correlation characteristics of the residual data, and
• wherein the ordered sequence of transform coefficients are subjected to the at least one data compression method to generate the encoded output data.

A method for decoding encoded data in a decoder to generate decoded output data, wherein the method comprises:

• (i) receiving encoded data at the decoder;
• (ii) applying an inverse transform to convert the received encoded data into enhancement-layer data that provides instructions for enhancing a base-layer reconstruction derived from a down-sampled version of the input data, wherein the enhancement-layer data comprises residual data to provide its enhancement, wherein the residual data are subjected to at least one transform and at least one data compression method to generate the received encoded data;
• (iii) decompressing the received encoded data according to the at least one data compression method to generate intermediate decoded data;
• and
• (iv) arranging for the inverse transform to include an inverse Hadamard transform to convert transform coefficients derived from the intermediate decoded data into the residual data, wherein different output elements of the Hadamard transform represent different encoded surfaces, each surface corresponding to a respective directional component of the transform, and wherein an output order traverses transform coefficients across multiple ones of the surfaces,
• wherein a content-dependent readout order has been communicated to the decoder to allow a corresponding readout order by the decoder, and
• wherein the transform coefficients are decoded by being read according to the corresponding readout order, the corresponding readout order comprising a tile raster manner or an n-by-n block “Z”-order, the readout output order operating over groups of coefficients spanning multiple surfaces and multiple coding units and is based on content-dependent spatial-correlation characteristics of the residual data.

A decoder for decoding encoded data to generate decoded output data, wherein the decoder includes:

• (i) an input for receiving encoded data;
• (ii) a data processing arrangement for applying an inverse transform to convert the received encoded data into enhancement-layer data that provides instructions for enhancing a base-layer reconstruction derived from a down-sampled version of the input data, wherein the enhancement-layer data comprises residual data to provide its enhancement, wherein the residual data are subjected to at least one transform and at least one data compression method to generate the encoded data;
• (iii) a decompression arrangement for decompressing the received encoded data using according to the at least one data compression method to generate intermediate decoded data;
• and
• (iv) an inverse transformation arrangement to apply the inverse transform as an inverse Hadamard transform to convert transform coefficients derived from the intermediate decoded data into the residual data, wherein different output elements of the Hadamard transform represent different encoded surfaces, each surface corresponding to a respective directional component of the transform, and wherein an output order traverses transform coefficients across multiple ones of the surfaces
• wherein the decoder is configured to receive a content-dependent readout order to allow a corresponding readout order by the decoder, and
• wherein the transform coefficients are decoded by being read according to the corresponding readout order, the corresponding readout order comprising a tile raster manner or a n-by-n block “Z”-order, the readout output order operating over groups of coefficients spanning multiple surfaces and multiple coding units and is based on content-dependent spatial-correlation characteristics of the residual data.