Intensity correction device for providing a correction signal for automatically correcting an intensity of a video signal

An intensity correction device comprising:

• a histogram memory for forming a histogram of an input luminance signal;
• a look-up table operating circuit for accumulating the histogram and normalizing the accumulated histogram so that the maximum cumulative frequency of occurrence of the input luminance signal becomes a maximum value of an output luminance signal;
• a look-up table memory for storing the normalized data and outputting a correction signal in response to the input luminance signal;
• a maximum value detecting circuit for detecting a maximum value of differences of the normalized data;
• and
• a multiplier for multiplying an inverse value of the maximum value detected by said maximum value detecting circuit and the correction signal.

An intensity correction device comprising:

• a histogram memory for forming a histogram of an input luminance signal;
• a look-up table operating circuit for accumulating the histogram and normalizing the accumulated histogram so that a maximum cumulative frequency of occurrence of the input luminance signal becomes a maximum value of an output luminance signal;
• a look-up table memory for storing the normalized data and outputting a correction signal in response to the input luminance signal;
• a maximum value detecting circuit for detecting a maximum value of differences of the normalized data;
• and
• a limiter for setting the correction signal to zero when said maximum value detected by the maximum value detecting circuit exceeds a predetermined value.

An intensity correction device comprising:

• a histogram memory for forming a histogram of an input luminance signal;
• a look-up table operating circuit for accumulating the histogram and normalizing the accumulated histogram so that a maximum cumulative frequency becomes a maximum value of an output luminance signal;
• a look-up table memory for storing the normalized data and outputting a correction signal in response to the input luminance signal;
• a maximum value detecting circuit for detecting a maximum value of differences of the normalized data;
• and
• a gain control circuit for varying gain of said correction signal depending upon said maximum value detected by said maximum value detecting circuit.