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Subjective evaluation of scale-space image coding

Six experiments are described in which the perceived quality of scale-space-coded color images has been assessed by means of numerical category scaling. 'Scale space' is a pyramidal multiresolution image-coding technique in which data reduction is accomplished by quantizing the prediction error signals on different scales of the pyramid. This coding technique has been applied to the luminance as well as the chrominance components of color images of three static complex scenes. The main coding parameters were degree of uniform quantization and scale level of a quantization error. The results show that the magnitude of impairment due to quantizing the prediction error signal on a given scale of the luminance component depends on the scale level as well as on the content of the scene, that high-resolution color information does not contribute to image quality, that perceptually distinct impairments combine according to a Minkowski metric with an exponent that is slightly above 2 and that perceptually similar impairments combine according to a Minkowski metric with an exponent that is slightly above 1 . The applicability of Allnatt's 'law of subjective addition' is discussed.