Picture Quality Compensation System Based on Brightness Polarity
The spatial frequency response of vision fluctuates with positive brightness polarity, a white figure against a gray background, and negative polarity, a black figure against a gray background. This article describes psycho-physical experiments showing that the line spread function of positive polarity always exhibits negative response at the surround. The line spread function of negative polarity exhibits positive polarity response at the surround at a low contrast and disappears at a high contrast. Picture edges glare when the compensation amount of a contour compensation circuit for a positive-negative symmetric picture increases because the edges of positive polarity are enhanced excessively. A circuit independently controlling contour components of positive polarity and negative polarity was made to perform picture-quality evaluation experiments. The experiments confirmed that picture quality is improved by a 0.5 step (using the 5-step rating scale evaluation) as compared with the conventional positive-negative symmetric waveform compensation circuit, and improvement can be achieved even under conditions of ambient lighting.
- Print ISSN
- 0036-1682
- Published
- 1985-02
- Content type
- Original Research
- DOI
- 10.5594/J14100