IMAGE CODING APPARATUS, IMAGE CODING METHOD, AND PROGRAM, AND IMAGE DECODING APPARATUS, IMAGE DECODING METHOD AND PROGRAM

摘要

The present invention is made to enable switching between lossless coding which prioritizes compatibility with a lossy coding process and lossless coding which prioritizes compression performance. An image coding apparatus of the present invention includes the following configuration. The image coding apparatus which encodes an image on a block-by-block basis includes a first coding unit and a second coding unit. The first coding unit performs irreversible compression coding on a received first block. The second coding unit performs reversible compression coding on a received second block. The second coding unit encodes the second block by using either of a first intra prediction mode for performing intra prediction on a block-by-block basis and a second intra prediction mode for performing intra prediction on a pixel-by-pixel basis.