This Recommendation | International Standard is applicable to continuous-tone - grayscale or colour - digital still image data. It is applicable to a wide range of applications which require use of compressed images. This Recommendation | International Standard: - defines extensions [including variable quantization@ selective refinement@ tiling@ and a Still Picture Interchange File Format (SPIFF)] to processes for converting Source image data to compressed image data; - defines extensions to processes for converting compressed image data to reconstructed image data; - defines coded representations for compressed image data; - gives guidance and examples on how to implement these extensions in practice; - describes compliance tests for these extensions.