Subjektive Bewertung von Verfahren der Farbsignalaufbereitung und -verarbeitung mit erweitertem Farbenraum und Konstant-Luminanz-Prinzip. Tl.1

The conventional method of generation and processing color components causes image defects, which can be avoided in a future HDTV-system: loss of sharpness and resolution by violation of the constant luminance principle, reduced color gamut and gamma adjustment which is not ideal. With the CIELAB-codec a coding procedure is introduced which avoids these deficiencies, but which has 'to be paid for' with increased hardware complexity at the receiver side. The extension of the color gamut and the observance of the constant luminance principle also has a series of effects on the noise performance of the total system. Therefore, the noise performance of several color coding procedures is theoretically analyzed as well as practically investigated by means of subjective tests with natural pictures. Suggestions are made for the selection of optimum chrominance axes and investigations are reported concerning the procedures of one- two- and three-dimensional prefiltering, subsampling and reconstruction for the chrominance components based on CIELAB-coding.