Video data correction device and video data correction method

1. A video data correction device comprising:

every time one frame's video data is input, an average luminance calculation section calculating an average luminance of video data, which was input, to output it as an average luminance level;

a delay section delaying by one-frame portion said average luminance level that is output from said average luminance calculation section;

when said video data is input, a table section outputting a pre-set maximum correction factor value;

a first correction factor calculation section comparing a plurality of correction thresholds, which differ in pre-set value, with said average luminance level from said average luminance calculation section to carry out weighting of said maximum correction factor value responding to a comparison result and to output it as a first correction factor value;

a second correction factor calculation section comparing said plurality of said correction thresholds with said average luminance level from said delay section to carry out weighting of said maximum correction factor value responding to a comparison result, and to output it as a second correction factor value; and

a correction section calculating an average value of said first and second correction factor values and simultaneously correcting said luminance level of said video data based on said calculated average value.

2. The video data correction device according to claim 1 ,

wherein said delay section was configured of a plurality of delay circuits delaying said average luminance levels sequentially, which were output from said average luminance calculation section, one-frame portion by one-frame portion, and

wherein said second correction factor calculation section was configured of a plurality of correction factor calculation sections that are provided responding to a plurality of said delay circuits, said plurality of said correction factor calculation sections comparing said average luminance levels from said plurality of said delay circuits with said plurality of said correction thresholds respectively to carry out weighting of said maximum correction factor value responding to a comparison result respectively, and to output them as correction factor values.

3. The video data correction device according to claim 1 ,

wherein, a threshold correction section is provided that, when a plurality of the correction thresholds are input, selects two correction thresholds from a plurality of said correction thresholds, which were input, calculates an average value of said selected correction thresholds, and simultaneously outputs said calculated average value together with said plurality of said correction thresholds that were input, and

wherein said first correction factor calculation section compares said plurality of said correction thresholds and said average value from said threshold correction section with said average luminance level from said average luminance calculation section, carries out weighting of said maximum correction factor value responding to a comparison result, and outputs it as a first correction factor value, and

wherein said second correction factor calculation section compares said plurality of said correction thresholds and said average value from said threshold correction section with said average luminance level from said delay section, carries out weighting of said maximum correction factor value responding to a comparison result, and outputs it as a second correction factor value.

4. The video data correction device according to claim 1 ,

wherein said average luminance calculation section is configured of;

an accumulator adding luminance component values of one-fame portion's video data cumulatively, based on a pixel clock and a vertical synchronizing signal of said video data; and

when said cumulative additional value from said accumulator is input, a multiplier multiplying this cumulative additional value by an inverse of number of pixels in said video data within one frame to calculate an average value of said luminance components of said video data and to output it as said average luminance level.

5. The video data correction device according to claim 1 ,

wherein said first and second correction factor calculation sections are configured of:

a plurality of comparators comparing size of said average luminance level, which was input, and a plurality of said correction thresholds respectively to decide height of said average luminance level;

a decoder outputting a multiplication factor of value that corresponded to height of said average luminance levels decided by said comparator; and

a multiplier multiplying said maximum correction factor value from said table section by said multiplication factor from said decoder, of which value increases as said average luminance level lowers, to output this multiplication result as a correction factor.

6. The video data correction device according to claim 1 ,

wherein said correction section is configured of:

a first adder adding said first and second correction factor values;

a multiplier calculating an average value of said first and second correction factor values from said additional value added by said first adder; and

a second adder adding said average data from said multiplier to said video data.

7. A video data correction method, comprising:

every time one frame's video data is input, a first step of calculating an average luminance of video data, which was input, to output it as an average luminance level;

a second step of delaying by one-frame portion said average luminance level calculated based on a process of said first step;

a third step of outputting a pre-set maximum correction factor value when said video data is input;

a fourth step of comparing a plurality of correction thresholds, which differ in pre-set value, with said average luminance level calculated based on said process of said first step to carry out weighting of said maximum correction factor value responding to a comparison result and to output it as a first correction factor value;

a fifth step of comparing said plurality of said correction thresholds with said average luminance level based on said process of said second step to carry out weighting of said maximum correction factor value responding to a comparison result, and to output it as a second correction factor value; and

a sixth step of calculating an average value of said first and second correction factor values and simultaneously correcting said luminance level of said video data based on said calculated average value.

8. The video data correction method according to claim 7 ,

wherein said process in said second step includes a seventh step of sequentially delaying said average luminance level calculated based on said process of said first step one-frame portion by one-frame portion, and

wherein said process in said fifth step includes an eighth step of comparing said plurality of said correction thresholds with each of said average luminance levels delayed based on said process of the said seventh step respectively to carry out weighting of said maximum correction factor value responding to a comparison result respectively, and to output them as correction factor values.

9. The video data correction method according to claim 7 ,

further comprising a ninth step of, when a plurality of said correction thresholds are input, selecting two correction thresholds from said plurality of said correction thresholds, which were input, to calculate an average value of said selected correction thresholds, and simultaneously to output a calculated average value together with said plurality of said correction thresholds that were input,

wherein a process in said fourth step includes a tenth step of comparing said plurality of said correction thresholds and said average value based on said process of said ninth step with said average luminance level calculated based on said process of said first step to carry out weighting of said maximum correction factor value responding to a comparison result, and to output it as a first correction factor value, and

wherein a process in said fifth step includes an eleventh step of comparing said plurality of said correction thresholds based on said process of said ninth step and said average value with said average luminance level based on said process of said second step to carry out weighting of said maximum correction factor value responding to a comparison result, and to output it as a second correction factor value.

10. The video data correction method according to claim 7 ,

wherein said process in said first step includes:

a twelfth step of cumulatively adding said luminance component values of one-fame portion's video data, based on a pixel clock and a vertical synchronizing signal of said video data; and

when said cumulative additional value based on said process of said twelfth step is input, a thirteenth step of multiplying this cumulative additional value by an inverse of number of pixels in said video data within one frame to calculate an average value of said luminance component of said video data and to output it as an average luminance level.

11. The video data correction method according to claim 7 ,

wherein said processes in said fourth and fifth steps include:

a fourteenth step of comparing size of said average luminance level, which was input, and said plurality of said correction thresholds respectively to decide height of said average luminance level;

a fifteenth step of outputting a multiplication factor of value that corresponded to height of said average luminance levels decided based on said process of said fourteenth step; and

a sixteenth step of multiplying said maximum correction factor value by said multiplication factor based on said process of said fifteenth step, of which value increases as said average luminance level lowers, to output this multiplication result as a correction factor.

12. The video data correction method according to claim 7 ,

wherein said process in said sixth step includes:

a seventeenth step of adding said first and second correction factor values;

an eighteenth step of calculating an average value of said first and second correction factor values from said additional value based on the process of said seventeenth step; and

a nineteenth step of adding said average data based on said process of said eighteenth step to said video data.