Picture quality improving circuit using a cumulative histogram

Details Picture quality improving circuit using a cumulative histogram Picture quality improving circuit using a cumulative histogram

1993-06-30

1995-02-07

Boudreau, Leo H.

Image analysis

Histogram processing

For setting a threshold

382 51, 348672, 358455, H04N 520

Patent

active

053881680

ABSTRACT:
A picture quality improving circuit for automatically obtaining a corrected image by capturing features of the input video signals. The circuit first compares an input luminance signal with a plurality of reference values, measures the results of the comparison by a plurality of counters and obtains a cumulative histogram within a predetermined period of time. Next, the cumulative histogram signals are stored in a latch circuit for a predetermined period of time, and an interpolation circuit determines and outputs a correction signal corresponding to the input luminance signal by interpolating the cumulative histogram. Accordingly, when a large number of dark signals exist in the input luminance signal, the cumulative histogram signals will describe an upwardly projecting graph, and the dark portions of the signal will be extended in a bright direction. Thereby, the picture quality can be improved.

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patent: 5157517 (1992-10-01), Byrne et al.
patent: 5296941 (1994-03-01), Izawa et al.

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