Color correction circuit, image display apparatus including the same, and color correction method

Abstract

A color correction circuit includes a 3D-LUT, an off data generation circuit, an image signal switchover circuit, and an interpolation operation circuit. The off data generation circuit substitutes respective lower (k−n) bits of input R, G, and B signals R2, G2, and B2 with a value ‘0’ and outputs processed R, G, and B signals after the substitution as off data Or, Og, and Ob. The off data generation circuit accordingly gives the output equivalent to the output of the 3D-LUT on the assumption that the storage of the 3D-LUT is rewritten to have identical input and output. The image signal switchover circuit alternatively selects and outputs standard data Sr, Sg, and Sb input from the 3D-LUT and the off data Or, Og, and Ob input from the off data generation circuit according to the setting of an externally given correction prohibit signal F. The color correction function of the color correction circuit is thus readily activated and inactivated, in response to the correction prohibit signal F. The arrangement of the invention effectively attains size reduction of the circuit scale and prevents the disturbance of image display due to deviation of the signal transfer timing, while enabling inactivation of the color correction function.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically illustrating the configuration of a liquid crystal projector including a color correction circuit in one embodiment of the invention;

FIG. 2 is a block diagram showing the structure of the color correction circuit of the embodiment;

FIG. 3 shows the structure of off data Or generated by an off data generation circuit included in the color correction circuit;

FIG. 4 shows one hardware configuration for inactivating the color correction function of the color correction circuit as a first reference example; and

FIG. 5 shows another hardware configuration for inactivating the color correction function of the color correction circuit as a second reference example.

Claims

1. A color correction circuit that receives three color signals representing a color image as input signals and performs signal processing of the input signals to correct the color of the color image displayed on an image display apparatus, the color correction circuit comprising:a standard data acquisition module that divides each of the three input color signals into an upper bit portion and a lower bit portion and acquires standard data for correction corresponding to a combination of the respective upper bit portions of the three color signals;an interpolation operation module that performs an interpolation operation of the standard data based on the respective lower bit portions of the three color signals to generate color-corrected output signals;an off data generation module that divides each of the three input color signals into an upper bit portion and a lower bit portion, which have identical bit widths with the bit widths of the upper bit portion and the lower bit portion by the standard data acquisition module, substitutes the respective lower bit portions of the three color signals with a value ‘0’, and outputs three processed color signals after the substitution as off data; andan interpolation object switchover module that, in response to an externally given correction prohibit instruction for prohibiting color correction, switches over an interpolation object of the interpolation operation module from the standard data to the off data.

2. The color correction circuit of claim 1, wherein the three color signals are a red color signal, a green color signal, and a blue color signal.

3. The color correction circuit of claim 1, wherein the standard data acquisition module has a three-dimensional lookup table that inputs the combination of the respective upper bit portions of the three color input signals as an address signal and outputs the standard data for correction corresponding to the combination of the respective upper bit portions of the three color images.

4. The color correction circuit of claim 3, wherein the three-dimensional lookup table stores the standard data for correction at each of lattice points specified by division of a color space of the three colors into lattices, the three-dimensional lookup table divides each unit cube defined by preset lattice points in the color space into multiple tetrahedrons and outputs the standard data at respective apexes of each of the multiple tetrahedrons, which include one specific point corresponding to a combination of tone values of the upper bit portions, andthe interpolation operation module performs linear interpolation of the standard data for correction output from the three-dimensional lookup table to generate color-corrected data corresponding to tone values of the lower bit portions.

5. The color correction circuit of claim 1, wherein the interpolation object switchover module includes a signal switchover circuit that receives both an output signal of the standard data acquisition module and an output signal of the off data generation module, and outputs the output signal of the off data generation module to the interpolation operation module in response to external input of the correction prohibit instruction, while outputting the output signal of the standard data generation module to the interpolation operation module in response to no external input of the correction prohibit instruction.

6. An image display apparatus including the color correction circuit in accordance with claim 1.

7. A color correction method of receiving three color signals that represent a color image as input signals and performing signal processing of the input signals to correct the color of the color image displayed on an image display apparatus, the color correction method comprising:dividing each of the three input color signals into an upper bit portion and a lower bit portion and acquiring standard data for correction corresponding to a combination of the respective upper bit portions of the three color signals;performing an interpolation operation of the standard data based on the respective lower bit portions of the three color signals to generate color-corrected output signals;dividing each of the three input color signals into an upper bit portion and a lower bit portion, which have identical bit widths with the bit widths of the divided upper bit portion and lower bit portion, substituting the respective lower bit portions of the three color signals with a value ‘0’, and outputting three processed color signals after the substitution as off data; andin response to an externally given correction prohibit instruction for prohibiting color correction, switching over an interpolation object of the interpolation operation from the standard data to the off data.