Abstract: The present invention discloses a method and an apparatus for correcting color mixing errors, which lets a color display device adopt a virtual material quantity concept and use at least one set of predetermined virtual primary colors to analyze mixed color signal values displayed on the color display device and establish a corresponding material characteristic functions between color control signal values and corresponding virtual control signal values, and eventually establish nonlinear color correction functions between a series of known control signal values corresponding to desired color signal values of the color display device, in such a way that when the color display device performs a video color conversion, the control signal values actually entered into the color display device are corrected to the corresponding target control signal values for allowing the color display device to display desired color signal values.

Abstract: An image processing apparatus carrying out a gamma correction for input data includes polygonal line approximating apparatus for carrying out the gamma correction by a polygonal line approximation, a look-up table partially storing gamma correction data corresponding to the input data, and a correction deciding portion and a selector which select the output of one of the polygonal line approximating apparatus and the look-up table corresponding to the input data.

Abstract: The present invention provides a technique for performing gamma correction processing when there are a plurality of characteristic areas, each of which is characterized by the high frequency in a luminance histogram to improve the impression of contrast. According to the present invention, a luminance characteristic detector (4) detects the luminance of an input image signal and a microcomputer (5) calculates an APL and a luminance histogram of an input image signal. A gamma correction circuit (6) performs the gamma correction processing in response to the luminosity of the input image signal by use of the result of the calculation carried out by the microcomputer (5). Then, if there are a plurality of characteristic areas, each of which is characterized by the high frequency in the luminance histogram, a characteristic emphasis circuit (7) performs grayscale extension processing for the plurality of characteristic areas.

Abstract: A CPU of a color printer performs gamma correction and a matrix operation M on an RGB color space image data derived by a matrix operation S. Using gamma correction value settings, the CPU performs gamma conversion of image data. Matrix operation M converts the RGB color space to an XYZ color space. When performing matrix operation M, the CPU refers to a PrintMatching tag and performs the matrix operation using a matrix (M) that corresponds to the indicated color space, in order to reflect the color space used for generation of image data.

Abstract: Embodiments of the invention provide a video display technique with which a stable video with a high contrast can be obtained according to brightness of a screen. In one embodiment, a video signal processing system for a video display apparatus which performs display on the basis of a video signal comprises a gain control module configured to provide a feedback signal based upon maximum luminance level information and average luminance level information of a luminance signal corresponding to the video signal, the feedback signal being used to control a gain of the luminance signal; and a correction module configured to apply a gamma correction based upon the average luminance level information to the video signal after the gain of the luminance signal has been controlled by the gain control module.

Abstract: A method (400) and a system (100) for providing video signals to video displays includes the steps of receiving at least one input video signal (150), dithering the non-uniformity color correction (445), applying the non-uniformity color correction to the input video signal to generate a color corrected video signal (450), and increasing a frame rate of the color corrected video signal (120). Gamma correction (125) can be applied to the color correction. Generating a dithered non-uniformity color correction can include selecting from a data storage (115) a plurality of RGB correction matrices (300), measuring at least one brightness level of the input video signal, selecting for the picture level correction a first RGB correction matrix if the brightness is within a first range of values (425), a second RGB correction matrix if the brightness is within a second range of values (435), and interpolating (440) the plurality of RGB correction matrices if the brightness is within a third range of values.

Abstract: A color signal processing apparatus for a multi-primary display with a simple circuit construction and a color signal processing method achieves a display white by more than four display primaries. The color signal processing apparatus has a tristimulus value calculation unit calculating tristimulus values (X, Y, Z) of an input color signal, a display primary control signal calculation unit calculating a control signal of each display primary to represent the color signal with a number of display primaries, and a control unit setting the control signal of each display primary with the control signal calculated by the display primary control signal calculation unit to display the color signal.

Abstract: An image processing system includes a frame store, a processing means and a monitor. The frame store stores a sequence of images from a film or video clip that will eventually be transferred to film for viewing in a theater. The image sequence is processed and possibly combined with other clips, resulting in changes to the color balance, intensity and contrast of the output clip. The image processing system, the monitor and the process of eventual transfer to film, have non-linear transfer characteristics, including gamma characteristics. These are combined in a single look-up table in a graphics card, so that images displayed on the monitor have an appearance matching that of the same images when viewed in the theater.

Abstract: A method of gamma correction includes selecting lower and upper reference curves corresponding to selected reference gamma values. A gamma correction curve is generated from a corresponding gamma correction value and cross-correlated with the upper and lower reference curves to generate a corresponding set of cross-correlation factors. The set of cross-correlation factors are stored and indexed to the corresponding gamma value. An input value is received for gamma correction with the corresponding gamma value. Data from the upper and lower reference curves indexed by the input value are then operated one with the cross-correlation factors to generate a gamma corrected output value.

Abstract: After a command signal corresponding to a gradation whose light emission is controlled is outputted from a controller IC 4, based on this, a combination of respectively different intensity conversion data are extracted from a linear data table 11 and a ? correction data table 12. The respective intensity conversion data are analog converted by a first DAC 13 and a second DAC 14, and these are converted into a voltage level of a mean value by resistors R1, R2 and an addition circuit 15. By this voltage level of the mean value, an absorption current in a current mirror circuit 16 is controlled, and as a result, a drive current accompanied by ? correction for the light emitting elements can be obtained by the current mirror circuit 16. The first DAC 13 and the second DAC 14 handle relatively simple intensity conversion data obtained from the linear data table 11 and the ? correction data table 12 and analog convert such data.

Abstract: This specification discloses a method of using locality statistics characteristic to enhance gamma corrections. Using the property that the color values of nearby digital image pixels are close to one another, the cache queue operation model is employed to partly replace the time-consuming table mechanism in the gamma correction procedure. The disclosed method first establishes a cache queue and then captures digital image pixels. According to the extracted digital image pixels, gamma correction values are searched to satisfy the cache queue. Finally, the gamma correction values corresponding to the digital image pixels are stored.

Abstract: In a projection type color display unit having three optical shutters formed on substrates corresponding to three primary colors, a color separation circuit and a digitalizing circuit are provided on each substrate having the optical shutter, and signals corresponding to the respective colors which are outputted from those three digitalizing circuits are compared with each other and arithmetically operated, to thereby reduce a noise.

Abstract: Apparatus for image capturing has preview function for monitor-outputting an image before capturing image to be recorded, image processing section including band correcting section for controlling frequency characteristic of color data constituting image data, gamma correcting section for controlling gradation characteristic of image data, pixel interpolating section for interpolating pixels with unknown data of each color data constituting image data, and exposure control section for controlling exposure setting value. Capture image size, image data compression rate or subject image recording mode can be met before capturing an image. Controller is selected according to capture image size, image data compression rate or image recording mode set before capturing the image.

Abstract: The present invention relates to controlling contrast in at least part of a picture. The contrast control is performed by reducing the saturation (2–4) of the picture during contrast increase (1).

Abstract: A video correction system and method are disclosed that provide video correction for an input signal. The system includes a logarithmic converter that creates a logarithmic representation of the input signal. A configurable corrector/converter comprises a plurality of associated components operative to process the logarithmic representation of the input signal. The configurable corrector/converter produces an output signal having at least one desirable signal characteristic. A switch control selects a configuration for the corrector/converter. The configuration indicates at least one of the plurality of associated components that will process the logarithmic representation.

Abstract: The present invention provides a gradation correction device which can perform gradation correction using digital feedback processing, and furthermore, can control the digital feedback processing with high accuracy. The gradation correction device is provided with a correction gain adjustable amount generation circuit (103) and a correction gain generation circuit (104), and the correction gain adjustable amount generation circuit (103) obtains a correction gain adjustable amount which is non-linear in relation to a difference S between a reference luminance level Yb1 and a maximum luminance level, and greater gamma correction is carried out as the value of the difference is larger.

Abstract: An apparatus comprising a first circuit and a second circuit. The first circuit may be configured to present a first portion of an output data stream in response to a first portion of an input data stream. The second circuit may be configured to present a second portion of the output data stream in response to a second portion of the input data stream. The apparatus may be configured to perform color and gamma correction on the input data stream to generate the output data stream in response to one or more control signals. In one example, the apparatus may comprise block move engine (BME).

Abstract: The color reproduction correction circuit which corrects the color distortion caused when color signals using the first combination of the three primary colors are reproduced in a color display of the second combination of the different primary color sources has been disclosed, wherein: a provided color correction circuit generates the mixed color signal by multiplying the color signal in question by the specified coefficients and adding the mixed color signal to other color signals; the mixed colors in the second combination are used as primary color light sources in the second combination; the specified coefficients are determined so that these mixed color light sources are made close to the coordinates of the primary color light sources of the first combination; and the luminescent chromaticity values of the three primary colors are corrected so that the chromaticity values of the device match those specified by the signal system.

Abstract: A method for restoring a light signal from digital data defining a colorimetric coordinate of the light signal in a specific colorimetric system, comprises the step of generating a first light signal using a first light restoration unit, the step of generating a second light signal using a second light restoration unit, and the step of generating a third light signal obtained by superimposing the first and second light signals. The second light restoration unit covers a brightness dynamics less than the brightness dynamics covered by the first restoration light unit. The second light restoration unit has a brightness resolution finer than the first light restoration unit.

Abstract: A method of CRT gamma correction of n-bit color and corresponding device are presented which employ a reduced size lookup table. An n-bit input signal is separated into its m most significant bits and (n−m) least significant bits. Instead of using its full n-bit value as the input address into a 2n×n lookup table, a 2m×n table employing only the m most significant bits is used, thereby reducing the memory requirements for the lookup table by a factor of 2(n−m). Every cycle, two consecutive memory locations are read, starting from where in the lookup table the m most significant bits of the input signal are pointing. The output of the lookup table provides the n-bit gamma corrected values for each of these m-bit inputs. A interpolation is then formed between these two output values and the n-bit, gamma corrected value of the full n-bit value of the input signal is then interpolated using its (m−n) least significant bits.

Abstract: A central symmetric Gamma voltage correction circuit is mainly applied to the displaying circuit of liquid-crystal display. By installing a resistor voltage dividing circuit and a driving circuit so that a well adjustment way to the Gamma correction voltage can be acquired. Moreover, the value of the Gamma correction voltage is controlled by externally inputting voltage, and thus the number of external correction reference voltage input externally and the number of the amplifiers are reduced. The resistor voltage dividing circuit and driving circuit are formed by a plurality of resistors, adjustable resistors and amplifiers so as to achieve the object of reducing the number of externally inputting correction voltages and the number of amplifiers.

Abstract: The color reproduction correction circuit which corrects the color distortion caused when color signals using the first combination of the three primary colors are reproduced in a color display of the second combination of the different primary color sources has been disclosed, wherein: a provided color correction circuit generates the mixed color signal by multiplying the color signal in question by the specified coefficients and adding the mixed color signal to other color signals; the mixed colors in the second combination are used as primary color light sources in the second combination; the specified coefficients are determined so that these mixed color light sources are made close to the coordinates of the primary color light sources of the first combination; and the luminescent chromaticity values of the three primary colors are corrected so that the chromaticity values of the device match those specified by the signal system.

Abstract: A gamma correction circuit has a data group generator which stores first to n-th gamma correction tables, receives first to n-th gains, and adjusts a level of the input signal using the first to n-th gamma correction tables and the first to n-th gains, thereby producing a gamma-corrected data group including first to n-th gamma-corrected data. The circuit also has a gamma characteristic controller which loads the first to n-th gains into the data group generator, a signal level discriminator which outputs a discrimination signal based on the level of the input signal, the first to n-th gamma correction tables, and the first to n-th gains, and an output selector which selects from among the first to n-th gamma-corrected data on the basis of a value of the discrimination signal, thereby producing the gamma-corrected output signal.

Abstract: An adjustable biased Gamma-correction circuit with central-symmetry voltage is disclosed. The present invention provides varistors, transistors, or operation amplifiers in a Gamma-correction circuit to obtain a plurality of plus and minus symmetrical driving voltages based on a central voltage. Utilizing the present invention, a Gamma-correction circuit can generate the most adjustable driving voltages by using the minimum voltage sources.

Abstract: An image processing system includes a frame store, a processing means and a monitor. The frame store stores a sequence of images from a film or video clip that will eventually be transferred to film for viewing in a theater. The image sequence is processed and possibly combined with other clips, resulting in changes to the color balance, intensity and contrast of the output clip. The image processing system, the monitor and the process of eventual transfer to film, have non-linear transfer characteristics, including gamma characteristics. These are combined in a single look-up table in a graphics card, so that images displayed on the monitor have an appearance matching that of the same images when viewed in the theater.

Abstract: A clamping circuit for supplying a clamped color signal to a gamma-correction circuit is provided with a clamping portion connected to a clamping voltage generating circuit. The clamping voltage generating circuit generates a clamping voltage in response to an individual control signal in such a way that the black level of a color signal coincides with the black level in an input/output characteristic of the gamma-correction circuit. The clamping portion adds this clamping voltage to the pedestal level of a color signal at a predetermined timing in response to a control signal, so as to absorb variations in black levels of the clamping levels and later-stage circuits including variation in the later-stage circuits.

Abstract: A color reproduction correcting system and method, and a video display device and method can reproduce original color by considering signal source and display device. Each signal source information and each display device information can be stored. The signal source and the display device, which are currently used (e.g., corrected), can be determined, for example, by a user selection. In one embodiment, the signal provided from a transmission side can be inverse gamma-corrected based on a corresponding signal source, and a colorimetric error of the inverse gamma-corrected signal is preferably corrected using corresponding signal source information and display device information. The corrected colorimetric error signal can be gamma-corrected based on a corresponding display device and then can be displayed on the corresponding display device.

Abstract: The display device is able to make an image of a dark scene to become easy to see without increasing a contrast. A composite video signal from an input terminal (1) is supplied to a separating circuit 2, in which it is separated to provide a luminance signal and two color-difference signals. The luminance signal thus separated is supplied to a dynamic gamma circuit (5). In this dynamic gamma circuit (5), its gamma correction curve between an input and an output thereof is changed in response to a control signal from a control circuit (11) in such a manner that an intermediate signal level is increased from approximately a straight line, for example. Then, the luminance signal thus gamma-corrected and two color-difference signals are converted by a converting circuit (6) into three primary color signals, and supplied through respective A/D-converting circuits (7R, 7G, 7B) to a display means (8) such as a plasma display or the like.

Abstract: An appropriate correction quantity is obtained for a video luminance signal on an individual video basis with a characteristic value, like the maximum or average value, of the luminance signal taken into account, thereby performing gray scale correction more effectively.

Abstract: A method (400) and a system (100) for providing video signals to video displays includes the steps of receiving at least one input video signal (150), dithering the non-uniformity color correction (445), applying the non-uniformity color correction to the input video signal to generate a color corrected video signal (450), and increasing a frame rate of the color corrected video signal (120). Gamma correction (125) can be applied to the color correction. Generating a dithered non-uniformity color correction can include selecting from a data storage (115) a plurality of RGB correction matrices (300), measuring at least one brightness level of the input video signal, selecting for the picture level correction a first RGB correction matrix if the brightness is within a first range of values (425), a second RGB correction matrix if the brightness is within a second range of values (435), and interpolating (440) the plurality of RGB correction matrices if the brightness is within a third range of values.

Abstract: A gamma corrector inputs a primary color signal as an image signal to each of the differential amplifiers which are connected in parallel to each other and mixes a plurality of output signals which are outputted from the four differential amplifiers to output an image signal to which a plurality of gamma correction is applied. Each of the differential amplifiers amplifies and outputs the inputted primary color signal with a different gain characteristic so that the gain characteristic of the signal obtained by mixing the output signals varies at two inflection points. The two-point gamma correction is applied to the inputted primary color signal so that a signal level at the side of a black level is turned down and the signal level at the side of a white level is turned up.

Abstract: A color signal processing apparatus for a multi-primary display with a simple circuit construction and a color signal processing method achieves a display white by more than four display primaries. The color signal processing apparatus has a tristimulus value calculation unit calculating tristimulus values (X, Y, Z) of an input color signal, a display primary control signal calculation unit calculating a control signal of each display primary to represent the color signal with a number of display primaries, and a control unit setting the control signal of each display primary with the control signal calculated by the display primary control signal calculation unit to display the color signal.

Abstract: The present invention relates to controlling contrast in at least part of a picture. The contrast control is performed by reducing the saturation (2-4) of the picture during contrast increase (1).

Abstract: An illumination intensity correcting circuit including a curve fitting circuit formed by differential amplifier circuits and a load resistor, wherein the amplification factor of the curve fitting circuit is changed before and after each breakpoint voltage, the reference voltages of the differential amplifier circuits are set so that at least two breakpoint voltages are arranged in the range of a voltage of a video signal, and the amplification factors of the differential amplifier circuits are set so that the amplification factor of the curve fitting circuit in the range of the signal voltage inside of the two breakpoint voltages is smaller than the amplification factor outside of the two breakpoint voltages.

Abstract: In the video processing device, a correction amount update determining unit determines whether to update a correction amount based on an input image obtained from an image input unit and when a cut point is detected or when the number of frames in a number of frames storing unit exceeds a fixed value, determines that update is required, and at this time, a correction amount obtaining unit obtains a new correction amount based on the input image. Then, if no cut point is detected, an amount of change of a correction amount in time is limited and the obtained result is recorded in a correction amount storing unit, and an image correcting unit conducts quality improving correction processing with respect to the input image based on a correction amount recorded in the correction amount storing unit and the image corrected is sent to an image output unit.

Abstract: A method of video signal processing that reduces computational and circuit costs. The method of processing a video signal of the present invention comprises the following steps: First, receiving a video input signal including an input luminance signal and input chrominance signals from a signal source. Next, correcting the input luminance signal of the video input signal to generate a corrected luminance signal. And finally outputting the corrected luminance signal and the input chrominance signals as the enhanced video signal to the subsequent video processor, such as a TV encoder, for converting the corrected signal from digital into analog. The correction of the luminance signal is accomplished by first normalizing the luminance signal by a predetermined value of a full-scale luminance. If the normalized luminance signal is greater than a first predetermined percentage, the corrected luminance signal is equal to the input luminance signal.

Abstract: A color signal adjustment module adjusts first through third color signals corresponding to first through third colors expressing a color image. The color signal adjustment device includes: first through fourth RAMs available as lookup tables for adjusting color signal levels; an address selection module that replaceably allocates the first through the third color signals and a predetermined address signal to input address signals of the first through the fourth RAMs, in response to a preset selection signal; and a data selection module that selectively outputs at least three output signals among output signals from the first through the fourth RAMs as first through third output color signals corresponding to the first through the third colors, in response to the preset selection signal.

Abstract: A signal of a vestigial sideband modulated wave is generated by use of a first oscillator, an amplitude-modulator and a surface acoustic wave filter for vestigial sideband filtering at a frequency being higher than the carrier frequency of a video signal, the signal is frequency-converted to a given transmission channel by use of a first PLL frequency synthesizer, a first control circuit, a frequency converter and a filter.

Abstract: A gamma correction circuit has a data group generator which stores first to n-th gamma correction tables, receives first to n-th gains, and adjusts a level of the input signal using the first to n-th gamma correction tables and the first to n-th gains, thereby producing a gamma-corrected data group including first to n-th gamma-corrected data. The circuit also has a gamma characteristic controller which loads the first to n-th gains into the data group generator, a signal level discriminator which outputs a discrimination signal based on the level of the input signal, the first to n-th gamma correction tables, and the first to n-th gains, and an output selector which selects from among the first to n-th gamma-corrected data on the basis of a value of the discrimination signal, thereby producing the gamma-corrected output signal.

Abstract: In a projection type color display unit having three optical shutters formed on substrates corresponding to three primary colors, a color separation circuit and a digitalizing circuit are provided on each substrate having the optical shutter, and signals corresponding to the respective colors which are outputted from those three digitalizing circuits are compared with each other and arithmetically operated, to thereby reduce a noise.

Abstract: An image processing system including a display output processor using Temporal Gamma Processing (TGP) and Reverse Super-resolution (RSR) techniques to process images. TGP assures that the time-related representation of an image is as accurate as possible, and thus, based on a previous frame value and a known transfer function of the display modulation system, adjusts its output values to provide a desired output value during display of a desired frame. RSR performs a superset of the frame rate conversion process for converting between disparate input and output frame rates. RSR, improving display quality when intended display images have apparent resolution higher than can be supported by an image modulator, sequences lower resolution images at higher frame rates to simulate higher resolution outputs.

Abstract: A display device has a &ggr; correction circuit based on line graph approximation. A memory stores &ggr; characteristic data of the display device. The &ggr; characteristic value, white level value, contrast value and black level value are input for adjusting the luminance characteristics of input video signals. A &ggr; conversion section sets a slope and intercept of the &ggr; correction so that the input video signal data can be converted to ideal output luminance value of the display.

Abstract: An illumination intensity correcting circuit including a curve fitting circuit formed by differential amplifier circuits and a load resistor, wherein the amplification factor of the curve fitting circuit is changed before and after each breakpoint voltage, the reference voltages of the differential amplifier circuits are set so that at least two breakpoint voltages are arranged in the range of a voltage of a video signal, and the amplification factors of the differential amplifier circuits are set so that the amplification factor of the curve fitting circuit in the range of the signal voltage inside of the two breakpoint voltages is smaller than the amplification factor outside of the two breakpoint voltages.

Abstract: An illumination intensity correcting circuit including a curve fitting circuit formed by differential amplifier circuits and a load resistor, wherein the amplification factor of the curve fitting circuit is changed before and after each breakpoint voltage, the reference voltages of the differential amplifier circuits are set so that at least two breakpoint voltages are arranged in the range of a voltage of a video signal, and the amplification factors of the differential amplifier circuits are set so that the amplification factor of the curve fitting circuit in the range of the signal voltage inside of the two breakpoint voltages is smaller than the amplification factor outside of the two breakpoint voltages.

Abstract: A video signal processing circuit in which nearly 100% of a largest possible dynamic range can be used, desired contrast is obtained, and desired brightness characteristics are obtained by an increasing in luminance of a screen. The circuit has an RGB amplifier which amplifies three primary color video signals R, G, and B by a predetermined gain and in which the gain is controlled by a gain control signal, A/D converters for converting analog three primary color video signals which are generated from the RGB amplifier into digital signals respectively, inverse gamma correcting circuits for effecting an inverse gamma correction to the three primary color digital video signals respectively, an OR circuit and a peak holding circuit for detecting peak levels of the analog three primary color signals, and a gain control signal generator for generating a gain control signal in accordance with the peak levels.

Abstract: A control point based real time primary custom gamma curve generator for color correction equipment. A separate custom gamma curve generator circuit is provided for each of the RBG and luminance channels. A plurality of control points is provided and stored in a lookup table (LUT) stored in a random access memory (RAM). The control points are set and/or adjusted by the operator or loaded from a prestored set (e.g. a default custom gamma curve). The instantaneous input signal is divided into two portions—a control point address portion comprising the most significant bits (MSBs) of the input signal, and an interpolation address portion comprising the least significant bits (LSBs) of the input signal. The MSBs are used to select a particular control point value stored in RAM. The LSBs are used for interpolation of values with a smooth curve between control points. Also described are various user interfaces for the custom gamma curve generator.

Abstract: A gamma correction circuit includes a main imaging signal processing circuit and a correction signal generating circuit. The main imaging signal processing circuit receives an input imaging signal (RGB signals: 3 three primary color signals) Si, and generates an output imaging signal on the basis of a predetermined reference voltage and an output resistance. Moreover, the correction signal generating circuit includes a plurality of current differential amplifiers connected in parallel with each other, and is configured so that the input imaging signal is supplied to the current differential amplifiers and each output of the current differential amplifiers is added to the generated output imaging signal from the main imaging signal processing circuit.

Abstract: Aiming to improve color reproducibility of a red part having high color saturation, a gamma compensation apparatus of the present invention is composed of a bending point setting block 100a and a gamma compensation block 101a and bending point setting block 100a is composed of a high APL detection circuit 1a inputting an average picture level of an input luminance signal and for detecting and taking out a signal component higher than a designated level; a gain controller 2a for gain controlling the detected signal at the high APL picture detection circuit; and an adder 3a for adding a designated offset to the output of gain controller 2a, and gamma compensation block 101a is composed of a slice circuit 4a inputting a color difference signal (R-Y) and the output of bending point setting block 100a and taking out a color difference signal component higher than the output signal level of bending point setting block 100a; a gain controller 5a for adjusting the output level of slice circuit 4a; and a subtracter 6a

Abstract: Image data to which gamma correction for a CRT has been applied is digitally gamma corrected to image data based on an applied voltage-transmittance characteristic of a liquid crystal display unit.A digital gamma correction circuit for correcting digital image data to which gamma correction for a CRT has been applied to digital image data suitable for driving display on liquid crystal display units 50R, 50G, 50B comprises a first digital gamma correction circuit 24 and a second digital gamma correction circuit 32. The first digital gamma correction circuit 24 applies a first gamma correction containing a correction for effectively restoring digital image data to which gamma correction for a CRT has been applied to the digital image data before gamma correction for a CRT was applied.

Abstract: The present invention relates to a gamma-correction circuit which can prevent the deterioration of focusing in a projection television. The gamma-correction circuit comprises a gamma-correction section having an input for receiving a blue color video signal and operable to generate a gamma-corrected signal, a peak-beam current limiting section connected to the gamma-correction section and operable to compare a beam current corresponding to the blue color video signal with a predetermined peak-level value, the peak-beam current limiting section further operable to clip or pass the gamma corrected signal according to the comparison, and a video amplifying section connected to the peak-beam current limiting section and operable to amplify clipped or passed signal, and output the amplified signal to a blue color CRT.