A data encoder configured for: - receiving image data with luminance values representing absolute luminance values L to be encoded; - encoding the received image data into reference encoded image data; and - outputting the reference encoded image data, wherein said encoding comprises mapping absolute luminance values L into digital code values D, the luminance values of the received image data being represented by the digital code values D in the reference encoded image data; wherein said mapping is based at least in part on an inverse of a functional model of: Y = max V 1 m − c 1 0 c 2 − c 3 V 1 m 1 n, wherein: Y is a normalized value of a corresponding one of the absolute luminance values L, wherein 0 ≤ Y ≤ 1, V is a normalized value of a corresponding one of the digital code values D that are output as reference encoded image data, wherein 0 ≤ V ≤ 1, and n, m, c 1, c 2, and c 3 are predetermined values, with: n = 2610 4096 x 1 4 ≃ 0.1593017578125; m = 2523 4096 x 128 ≃ 78.84375; c 1 = c 3 − c 2 + 1 = 3424 4096 ≃ 0.8359375; c 2 = 2413 4096 x 32 ≃ 18.8515625; and c 3 = 2392 4096 x 32 ≃ 18.6875. - receiving image data with luminance values representing absolute luminance values L to be encoded; - encoding the received image data into reference encoded image data; and - outputting the reference encoded image data, wherein said encoding comprises mapping absolute luminance values L into digital code values D, the luminance values of the received image data being represented by the digital code values D in the reference encoded image data; wherein said mapping is based at least in part on an inverse of a functional model of: Y = max V 1 m − c 1 0 c 2 − c 3 V 1 m 1 n, wherein: Y is a normalized value of a corresponding one of the absolute luminance values L, wherein 0 ≤ Y ≤ 1, V is a normalized value of a corresponding one of the digital code values D that are output as reference encoded image data, wherein 0 ≤ V ≤ 1, and n, m, c 1, c 2, and c 3 are predetermined values, with: n = 2610 4096 x 1 4 ≃ 0.1593017578125; m = 2523 4096 x 128 ≃ 78.84375; c 1 = c 3 − c 2 + 1 = 3424 4096 ≃ 0.8359375; c 2 = 2413 4096 x 32 ≃ 18.8515625; and c 3 = 2392 4096 x 32 ≃ 18.6875. wherein said encoding comprises mapping absolute luminance values L into digital code values D, the luminance values of the received image data being represented by the digital code values D in the reference encoded image data; wherein said mapping is based at least in part on an inverse of a functional model of: Y = max V 1 m − c 1 0 c 2 − c 3 V 1 m 1 n, wherein: Y is a normalized value of a corresponding one of the absolute luminance values L, wherein 0 ≤ Y ≤ 1, V is a normalized value of a corresponding one of the digital code values D that are output as reference encoded image data, wherein 0 ≤ V ≤ 1, and n, m, c 1, c 2, and c 3 are predetermined values, with: n = 2610 4096 x 1 4 ≃ 0.1593017578125; m = 2523 4096 x 128 ≃ 78.84375; c 1 = c 3 − c 2 + 1 = 3424 4096 ≃ 0.8359375; c 2 = 2413 4096 x 32 ≃ 18.8515625; and c 3 = 2392 4096 x 32 ≃ 18.6875. Y is a normalized value of a corresponding one of the absolute luminance values L, wherein 0 ≤ Y ≤ 1, V is a normalized value of a corresponding one of the digital code values D that are output as reference encoded image data, wherein 0 ≤ V ≤ 1, and n, m, c 1, c 2, and c 3 are predetermined values, with: n = 2610 4096 x 1 4 ≃ 0.1593017578125; m = 2523 4096 x 128 ≃ 78.84375; c 1 = c 3 − c 2 + 1 = 3424 4096 ≃ 0.8359375; c 2 = 2413 4096 x 32 ≃ 18.8515625; and c 3 = 2392 4096 x 32 ≃ 18.6875.