Subjective assessment of impairment in scale-space-coded images

Direct category scaling and a scaling procedure in accordance with Functional Measurement Theory (Anderson, 1982) have been used to assess impairment in scale-space-coded illlages, displayed on a black-and-white TV monitor. The image of a complex scene was passed through a Gaussian filter of limited bandwidth. A 'prediction image' of the original image was made from this bandlimited signal. The degree of quantisatioll of the 'prediction error image' , obtained by subtracting the prediction image from the original one, determined the impairment in the reconstructed image. Category scaling of impairment and category scaling of differences ill impairment, created by presenting the images according to a factorial design as dictated by Functional MeiUlurement Tileory, gave the same monotone S-shaped relation between impairment and size of the quantisation step. The impairment consisted of unsharpness and occurrence of speckles. A second series of experiments was carried out to scale these percepts. The relation between unsharplless, occurrence of speckles and impairment is discussed.