Television – Image signal processing circuitry specific to television – Gray scale transformation
Reexamination Certificate
1998-10-08
2001-08-21
Eisenzopf, Reinhard J. (Department: 2614)
Television
Image signal processing circuitry specific to television
Gray scale transformation
C348S254000, C348S671000, C348S678000, C348S687000, C358S519000, C345S087000
Reexamination Certificate
active
06278496
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital &ggr; correction circuit that performs &ggr; correction on digital brightness data and digital density data corresponding to the &ggr; characteristics of LCDS, scanners, printers and so forth. Moreover, the present invention relates to an image data processing apparatus equipped with this type of &ggr; correction circuit, contrast control circuit, brightness control circuit and so forth.
2. Description of the Prior Art
Known methods employed in the form of this type of digital &ggr; correction circuit of the prior art include a method wherein converted values corresponding to the &ggr; characteristics of an LCD, scanner, printer and so forth were stored in ROM in advance, after which digital brightness data or digital density data prior to correction was applied to ROM in the form of an address to perform &ggr; correction, and a method wherein digital brightness data or digital density data X prior to correction was divided into a plurality of regions, after which an operation was performed on each region by an arithmetic processing circuit according to the following formula to perform &ggr; correction.
Y=AX+B
where, Y is the output value and A is the slope of the crossover line for &ggr; correction of each individual region.
However, in the method that uses ROM, increasing the number of correction curves requires a corresponding increase in the number of ROM, thereby resulting in problems such as increased costs and increased circuit area. Similarly, in the method that uses an arithmetic processing circuit, increasing the number of crossover lines for &ggr; correction results in an increase in circuit size as well as longer processing time.
SUMMARY OF THE INVENTION
The present invention was completed to solve the above-mentioned problems, having the characteristics described below.
The present invention provides a digital &ggr; correction circuit that corrects digital input data based on a &ggr; correction crossover line to generate digital output data, which respectively fixes a plurality of crossover point positions in the input data axial direction of said &ggr; correction crossover line in the form of fixed positions, is able to specify predetermined slope data respectively corresponding to a plurality of regions formed bordering on the fixed positions, comprising: a crossover point arithmetic processing circuit, which performs arithmetic processing on crossover point positions in the output data axial direction of said &ggr; correction crossover line at each of said plurality of regions using said specified slope data and said fixed positions prior to input of said input data; and, a real-time processing circuit, which performs &ggr; correction on a real-time basis on said input data based on crossover point positions in said output data axial direction arithmetically processed with said crossover point arithmetic processing circuit and said specified slope data to generate said corresponding output data.
In addition, in another aspect of the present invention, the present invention provides a digital &ggr; correction circuit that corrects digital input data based on a &ggr; correction crossover line to generate digital output data, which sets crossover point positions in the input data axial direction of said &ggr; correction crossover line in advance, divides said &ggr; correction crossover line into a plurality of regions bordering on each of said crossover point positions, comprising: a crossover point arithmetic processing circuit, which performs arithmetic processing on crossover point positions in the output data axial direction of said &ggr; correction crossover line in each of said plurality of regions based on slope data respectively specified for each of said plurality of regions and crossover point positions in the axial direction of said input data set in advance; a first selection circuit, which selects one piece of slope data specified corresponding to each of said plurality of regions according to a predetermined upper bit of said input data; a second selection circuit, which selects one crossover point position in said output data axial direction arithmetically processed in said crossover point arithmetic processing circuit corresponding to each of said plurality of regions according to a predetermined upper bit of said input data; a difference calculation circuit, which calculates the difference from the crossover point position in said input data axial direction to the position in said input data axial direction in the region to which said input data belongs among said plurality of regions based on said input data; and an arithmetic processing circuit, which multiplies the difference calculated by said difference calculation circuit by slope data selected by said first selection circuit, adds the resulting multiplication result to the value of the crossover point position selected by said second selection circuit, and outputs the resulting addition result in the form of a &ggr; correction value of said input data.
As has been explained above, according to the digital &ggr; correction circuit as claimed in the present invention, since crossover point position Xx in the input data axial direction of a &ggr; correction crossover line is taken to be a fixed position, and arithmetic processing of a crossover point in the output data axial direction, for which there is a larger volume of arithmetic processing, is performed prior to input of data, real-time processing during data input is faster and the circuit scale can be made to be smaller.
In addition, by selecting a plurality of slopes and a plurality of crossover point positions Yx in the output data axial direction corresponding to a predetermined upper bit of input data, arithmetic processing can be simplified.
In addition, in another aspect of the present invention, said crossover point arithmetic processing circuit performs arithmetic processing on said crossover point positions in the output data axial direction in said plurality of regions by bit-shifting slope data specified corresponding to each of said plurality of regions according to the size in said input data axial direction of said corresponding regions, and adding the shift result to crossover point positions in the output data axial direction of a previously determined adjacent region.
In this manner, arithmetic processing can be performed faster since crossover points in the output data axial direction of a &ggr; correction crossover line are arithmetically processed by shifting a plurality of slope data respectively specified for each region for each bit according to the size of that region, and adding the shift results for each individual region.
Moreover, in yet another aspect of the present invention, said input data is a video signal, and said crossover point arithmetic processing circuit updates the arithmetic processing results that are output to arithmetic processing results to be output next during a vertical blanking period of said video signal.
If results are updated during this type of period, since there is no display during this blanking period, suitable &ggr; correction processing can be performed on a real-time basis for each screen without having an effect on the display.
In addition, in still another aspect of the present invention, the present invention provides an image data processing circuit which is a &ggr; correction circuit that performs &ggr; correction processing on an integer n bits of image data that is input, and output “n+integer &agr;” bits of image data when a is taken to be a positive integer, which respectively fixes a plurality of crossover point positions in the input data axial direction of said &ggr; correction crossover line in the form of fixed positions, is able to specify predetermined slope data respectively corresponding to a plurality of regions formed bordering on the fixed positions, said circuit comprising: a crossover point arithmetic processing circuit, which perform
Fujioka Makoto
Kitagawa Makoto
Kobayashi Mitsugu
Tsutsui Yusuke
Uehara Hisao
Desir Jean W.
Eisenzopf Reinhard J.
Hogan & Hartson LLP
Sanyo Electric Co,. Ltd.
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