Encoder for encoding a picture into a quality-scalable data stream, comprising: base encoding means for encoding the picture into a base encoding data stream representing a representation of the picture with a first picture sample bit depth; prediction means for providing a prediction of the picture based on the representation of the picture with the first picture sample bit depth, the prediction of the picture having a second picture sample bit depth being higher than the first picture sample bit depth; and residual encoding means for encoding a prediction residual of the prediction into a bit-depth enhancement layer data stream; and combining means for forming the quality-scalable data stream based on the base encoding data stream and the bit-depth enhancement layer data stream, wherein the prediction means further comprises mapping means for performing, on the representation of the picture with the first picture sample bit depth, a mapping of samples from a first dynamic range corresponding to the first picture sample bit depth to a second dynamic range greater than the first dynamic range and corresponding to the second picture sample bit depth to obtain the prediction of the picture, characterized in that the mapping means is adapted to map the samples x from the first dynamic range to the second dynamic range by computing 2 M-N-K x + 2 M -1 - 2 M- 1 -K, where N is the first picture sample bit depth, M is the second picture sample bit depth, and K is a mapping parameter, and wherein the mapping means is adapted to forward the mapping parameter K to the combining means for formation of the quality-scalable data stream also based on the mapping parameter. base encoding means for encoding the picture into a base encoding data stream representing a representation of the picture with a first picture sample bit depth; prediction means for providing a prediction of the picture based on the representation of the picture with the first picture sample bit depth, the prediction of the picture having a second picture sample bit depth being higher than the first picture sample bit depth; and residual encoding means for encoding a prediction residual of the prediction into a bit-depth enhancement layer data stream; and combining means for forming the quality-scalable data stream based on the base encoding data stream and the bit-depth enhancement layer data stream, wherein the prediction means further comprises mapping means for performing, on the representation of the picture with the first picture sample bit depth, a mapping of samples from a first dynamic range corresponding to the first picture sample bit depth to a second dynamic range greater than the first dynamic range and corresponding to the second picture sample bit depth to obtain the prediction of the picture, characterized in that the mapping means is adapted to map the samples x from the first dynamic range to the second dynamic range by computing 2 M-N-K x + 2 M -1 - 2 M- 1 -K, where N is the first picture sample bit depth, M is the second picture sample bit depth, and K is a mapping parameter, and wherein the mapping means is adapted to forward the mapping parameter K to the combining means for formation of the quality-scalable data stream also based on the mapping parameter.