Nonlinear Amplitude Modification (e.g., Gamma) Patents (Class 348/674)
  • Patent number: 6633343
    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.
    Type: Grant
    Filed: March 12, 2001
    Date of Patent: October 14, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Keiichi Ito, Atsuhisa Kageyama, Nobutaka Okada, Katsuya Ishikawa, Hidetoshi Suzuki, Hisao Kunitani, Yuki Kakuya
  • Publication number: 20030160901
    Abstract: The invention includes a circuit for applying a transfer function to correct values of an input signal. The transfer function is approximated by piecewise-linear segments generated by a plurality of segment operators. An input line in the circuit receives the input signal. Window detectors determine a value of the input signal, and select one of the segment operators based on the value of the input signal. The selected segment operator applies a correction value to correct the value of the input signal. Each of the segment operators generates a different linear segment of the piecewise-linear segments. Each of the segment operators simultaneously generates a respective correction value responsive to the value of the input signal. In one embodiment, a multiplexer selects one of the respective correction values to correct the value of the input signal.
    Type: Application
    Filed: February 28, 2002
    Publication date: August 28, 2003
    Inventor: Robert Joseph Topper
  • Publication number: 20030156226
    Abstract: A gamma correction circuit for correcting a digital video signal, the circuit comprising first (6) and second (8) lookup tables for storing discrete output intensity data and the associated slope data of a non-linear transfer function, respectively, for each of the discrete input video signal intensities, an adder (10) having a first input connected to the output of the first lookup table, a multiplier (12) having a first input connected to the output of the second look-up table (8), characterized by a quantizer (4) for providing the most significant bits of the incoming video signal to address the first (6) and second (8) lookup tables and to transfer the corresponding output intensity data to the adder (10) and the associated slope data to the multiplier (12), the quantizer (4) transmitting the remaining least significant bits of the input video signal to the second input of the multiplier (12), the multiplier (12) multiplying the slope data with the remaining least significant bits and feeding the multipli
    Type: Application
    Filed: February 15, 2002
    Publication date: August 21, 2003
    Inventors: Jeroen Hubert Christoffel Jacobus Stessen, Andrea Maccato, Mitchell Oslick
  • Patent number: 6593934
    Abstract: This invention is related to an automatic Gamma correction system in which a novel display driving circuitry is designed with a digital/analog converter (DAC), wherein the Gamma reference voltages as well as the corresponding gray-scale values are adjustable. Therefore, the present invention provides a greater degree of freedom for the realization of the correction of Gamma parameters so as to fit the curve representing the transfer function of the destination gray-scale values and the voltages required by the display driving circuitry.
    Type: Grant
    Filed: November 16, 2000
    Date of Patent: July 15, 2003
    Assignee: Industrial Technology Research Institute
    Inventors: Ming-Jiun Liaw, Ho-Hsin Yang, Yuh-Ren Shen
  • Publication number: 20030128299
    Abstract: A method and system are disclosed that correct pixel values for output on a video display utilizing gamma correction. The method provides improved gamma correction by determining a first range of pixel values to be displayed on the video display and then determining a second range of pixel values to be displayed on the same display. Next, the method determines a first level of gamma correction to be provided for the first range of pixel values. This first level of gamma correction is provided at a first level of precision. Next, the method provides a second level of gamma correction to the second range of pixel values at a second level of precision. The second level of precision is different than that of the first level and is typically less than the first level.
    Type: Application
    Filed: January 4, 2002
    Publication date: July 10, 2003
    Inventors: Terrence J. Coleman, Kenneth C. George
  • Patent number: 6587584
    Abstract: In an apparatus for gamma correcting image data including a first image data, a second image data and a third image data, the apparatus includes: a first clock generator for generating a first clock; a second clock generator for generating a second clock, wherein the second clock has a frequency a predetermined times as fast as the first clock; an image data input unit for storing the image data in response to a first clock; a first selecting unit for selectively outputting the image data in response to a second clock; a second selecting unit for selectively outputting a starting point value of corresponding image data in response to the second clock; a third selecting unit for selectively outputting a gamma slope value of corresponding image data in response to the second clock; a piecewise gamma correction unit for receiving output values from the first, the second and the third selecting unit to generate gamma corrected image data; and an output unit for storing the gamma corrected image data a predetermin
    Type: Grant
    Filed: June 27, 2000
    Date of Patent: July 1, 2003
    Assignee: Hyundai Electronics Industries Co., Ltd.
    Inventor: Hoai-Sig Kang
  • Patent number: 6577285
    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.
    Type: Grant
    Filed: October 14, 1999
    Date of Patent: June 10, 2003
    Assignee: Sony Corporation
    Inventors: Hitoshi Motonakano, Shozo Mitarai
  • Patent number: 6573934
    Abstract: Digital correction of non-linearity using a piecewise linear approximation method generates uniform errors of minimal magnitude regardless of the size of an input signal. The non-linear curve is partitioned into a number of sections which are increased over conventional techniques, without increasing the number of function values, or the amount of hardware required. A non-linear curve is divided into a first direct line and a second direct line using a piecewise linear approximation method. A third direct line links two points spaced to either side of an inflection point at the intersection of the first and second direct lines by a predetermined distance. The slope of the third direct line corresponds to the average of the slopes of the first and second direct lines. When an input x lies in the section of the third direct line, a corrected signal according to the third direct line is generated.
    Type: Grant
    Filed: December 3, 1998
    Date of Patent: June 3, 2003
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Je-suk Lee
  • Patent number: 6570611
    Abstract: An image display device has a first look-up table memory (4) for correcting a gamma curve of an input video signal so as to correct a gradation of a display image, a second look-up table memory (5) for generating uniformity correction data on a screen at each gradation level, and a positional information generating portion (10) for generating uniformity correction data corresponding to a position on the screen. A correction data making portion (6) synthesizes the uniformity correction data output from the second look-up table memory (5) and the uniformity correction data output from the positional information generating portion (10). An arithmetic processing circuit (7) corrects the video signal that has been subjected to the gradation correction and read out from the first look-up table memory (4) by using the uniformity correction data output from the correction data making portion (6), and the uniformity correction of the display image is performed at all gradation levels.
    Type: Grant
    Filed: September 20, 2000
    Date of Patent: May 27, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroaki Satou, Tetsuro Shiota, Hiroshi Miyai
  • Patent number: 6567124
    Abstract: An imaging system for achieving enhanced image detail includes a sensor subsystem, an electronic image processing subsystem, and an automatic gain control (AGC) unit. The sensor unit is operative for sensing an image received from an exterior environment and for converting the image to an electrical representation having a peak value that is related to the dynamic range of the image. The electrical representation is then processed in the electronic image processing subsystem using a unique multiple order, non-linear transfer function that processes the signal in a manner that is dependent upon the dynamic range of the input image. The output signal of the electronic image processing subsystem is then applied to the AGC unit which performs a conventional AGC function on the signal. Thus, the imaging system automatically adjusts to changing scene content in the input image in a dynamic manner.
    Type: Grant
    Filed: December 1, 1999
    Date of Patent: May 20, 2003
    Assignee: Ball Aerospace & Technologies Corp.
    Inventor: Tuan Tran
  • Publication number: 20030071923
    Abstract: A system and method for performing real-time gamma correction of video in which a pixel having multiple components, e.g., RGB components, can be gamma corrected through a single access to a lookup table.
    Type: Application
    Filed: November 22, 1999
    Publication date: April 17, 2003
    Inventor: MICHAEL A. ESKIN
  • Patent number: 6542143
    Abstract: It is an object to provide a high-performance display element driving device or the like which can be easily reduced in power consumption and scale. A display element driving device (100) drives a liquid crystal serving as a capacitive display element. A D/A converter (110) includes first to Nth charge storage sections (112-1) to (112-N) for receiving first to Nth digital data corresponding an image signal and storing charges corresponding to the values of the first to Nth digital data, and first to Nth connection sections (114-1) to (114-N) for electrically connecting the first to Nth charge storing sections (112-1) to (112-N) and an electrode line (130) to each other and discharging the stored charges to the electrode line (130) at a given timing. In this manner, &ggr;-correction of a liquid crystal and D/A conversion can be simultaneously performed, and conversion from RGB to YUV and D/A conversion can be simultaneously performed.
    Type: Grant
    Filed: February 5, 1998
    Date of Patent: April 1, 2003
    Assignee: Seiko Epson Corporation
    Inventor: Tokuroh Ozawa
  • Patent number: 6535255
    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.
    Type: Grant
    Filed: September 25, 2001
    Date of Patent: March 18, 2003
    Assignee: Sony Corporation
    Inventors: Hitoshi Motonakano, Shozo Mitarai, Akira Arimizu
  • Publication number: 20030025837
    Abstract: Digital correction module for video projector where a correction module is provided to give a non-linear re-imaging of an image so that it is displayed correct on a non-ideal screen (curved screen) where a correction module is provided in each of a plurality of video projectors after a common image source in order to create a large, of several composite sub image, projected image of said image source. The correction module comprises a sequencer (1), a pixel write control (2), a parameter storage (7), a read address generator (13), a coefficient generator (5), a scaling generator (6), an adder (8), a pixel storage (3), a vertical mixer (9), a horizontal mixer (10) and a look up function means (12) for correction of differences in the border area of the image of the respective projectors such as geometry correction, soft transition tuning, vignette correction and gamma correction.
    Type: Application
    Filed: August 5, 2002
    Publication date: February 6, 2003
    Inventors: Knut Krogstad, Johan Henrik Liteskare
  • Patent number: 6515699
    Abstract: High frequency components of a video signal are attenuated for avoiding aliasing when the video signal is corrected by a non-linear gamma correction circuit. Such high frequency components arise from the video signal harmonics, and also are generated in image contour processing of the video signal. The high frequency components are band limited, thereby linearizing the gamma correction circuit and preventing aliasing. Up-converting the sampling frequency increases a desired band limitation area and defers the generation of high frequency components that cause aliasing. The non-linear gamma correction function is divided into a plurality of sections which are replaced by respective straight-line segments each represented by a linear expression, and gamma correction is effected with a straight-line segment corresponding to the amplitude of the digital video signal.
    Type: Grant
    Filed: July 31, 1996
    Date of Patent: February 4, 2003
    Assignee: Sony Corporation
    Inventors: Ichiro Tanji, Fumihiko Sudo, Taku Kihara
  • Publication number: 20020176024
    Abstract: A process of effecting various anti compensation processes on input image on a plasma display panel comprises the steps of a) performing a gamma (i.e., &ggr; equal to 0.45) compensation process on a video signal received by the PDP with respect to a &ggr;; b) dividing the video signal into at least two segments based on a gray level thereof; and c) performing a variety of anti compensation processes on the video signal in respective segment. A smaller &ggr; is used in the anti compensation process with respect to the video signal in a range of low gray level for increasing the gray level in the range of low gray level. Similarly, a larger &ggr; is used in the anti compensation process with respect to the video signal in a range of high gray level for increasing a gradient in the range of high gray level, thereby obtaining a sharp image contrast, improving image quality, and rendering an enhanced image brightness.
    Type: Application
    Filed: May 18, 2001
    Publication date: November 28, 2002
    Inventors: Shiuh-Bin Kao, Liang-Kuei Hsu, Kuang-Lang Chen
  • Publication number: 20020145598
    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.
    Type: Application
    Filed: April 5, 2001
    Publication date: October 10, 2002
    Applicant: INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE
    Inventors: Yuhren Shen, Chien-Chih Chen, Ming-Daw Chen, Ming-Jiun Liaw
  • Patent number: 6462735
    Abstract: A display device in which brightness and contrast in an electro-optical device are improved, and gain adjustment and brightness adjustment are not necessary. The present invention provides a device which drives a liquid crystal device in which light transmittance ratio changes based on applied voltage. Furthermore, a digital picture signal is gamma-corrected in a digital gamma correction circuit, and subsequently converted into an analog signal in a D/A conversion block and supplied to the liquid crystal device. The digital gamma correction circuit converts an 8-bit digital picture signal into a 10-bit digital picture signal based on gamma correction characteristics predetermined by applied voltage-transmittance characteristics inherent in the liquid crystal device in the entire transmittance range of 0% and 100%.
    Type: Grant
    Filed: July 6, 1999
    Date of Patent: October 8, 2002
    Assignee: Seiko Epson Corporation
    Inventor: Keijiro Naito
  • Publication number: 20020130975
    Abstract: A method of characterizing a video display, including the steps of providing a mathematical model of the display that relates code values to luminance output of the display, the model having a parameter that characterizes the display; displaying a reference patch and a test patch simultaneously on the display, the reference patch having a reference brightness produced by one or more luminances and the test patch having an test brightness produced by rapidly switching back and forth between two luminances; observing the display while varying one of the luminances keeping the others fixed, until the apparent brightness of the reference patch matches the apparent brightness of the test patch, and recording the code values employed to produce the luminances when a best match is made, and using the mathematical model, and the recorded code values to determine the value of the parameter that characterizes the display.
    Type: Application
    Filed: March 15, 2001
    Publication date: September 19, 2002
    Applicant: Eastman Kodak Company
    Inventors: Jian Yang, Michael E. Miller
  • Patent number: 6441563
    Abstract: A dynamic color temperature and color deviation calibration method is provided for eliminating problems associated with color temperature change and color deviation caused by an emissivity change of red, green and blue phosphor layers of a plasma display panel (PDP). The method comprises the steps of utilizing laws of color matching for calculating an emissivity change of a pixel of the PDP in response to a brightness change of one of red, green, and blue lights emitted by a corresponding one of red, green and blue discharge cells of the PDP through a numeric operation; dynamically adjusting brightness of one of the emitted red, green, and blue lights by increasing or decreasing strength of input video signal of each of the discharge cells; and eliminating a color temperature and a color deviation of the PDP due to an emissivity change. This can render an image having an optimum color purity and color temperature by eliminating adverse effects on PDP due to emissivity change.
    Type: Grant
    Filed: May 18, 2001
    Date of Patent: August 27, 2002
    Assignee: Chunghwa Picture Tubes, Ltd.
    Inventors: Shiuh-Bin Kao, Yi-Sheng Yu, Kuang-Lang Chen, Ching-Hui Lin
  • Patent number: 6441870
    Abstract: A system has video output connections capable of connecting to different display devices. The system has input connections capable of receiving image signal from multiple sources. A table of gamma values is indexed by both the display type and image source type. A software or hardware module applies a gamma correction from the table to the received video to transform it to have a gamma consistent with that of the display device. In a further embodiment, the images are encoded with a gamma identifier which is used to index into the table of system gammas. A video card that detects video source and display is also described. The video card utilizes a table of gamma values indexed by video source and display type and operating mode. Images are then corrected by the card to display properly on the display.
    Type: Grant
    Filed: December 22, 1998
    Date of Patent: August 27, 2002
    Assignee: Gateway, Inc.
    Inventor: Mark Rapaich
  • Patent number: 6433838
    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.
    Type: Grant
    Filed: January 31, 2000
    Date of Patent: August 13, 2002
    Assignee: Winbond Electronics Corporation
    Inventor: An-Tung Chen
  • Patent number: 6433823
    Abstract: A solid state image sensing device provided with a gamma correction circuit which corrects a logarithmically converted value derived from the logarithmic conversion of individual pixel data output from individual photoelectric conversion elements, thereby easily correcting discrepancies and differences in the gamma characteristics of the individual pixels of a photoelectric conversion element which converts a light signal to an electrical signal.
    Type: Grant
    Filed: August 26, 1997
    Date of Patent: August 13, 2002
    Assignee: Minolta Co., Ltd.
    Inventors: Satoshi Nakamura, Kenji Takada
  • Patent number: 6424281
    Abstract: Disclosed is a DAC (digital/analog converter) with adjustable digital codes corresponding to reference voltages, in which a novel DAC designed with an associated circuit is used in non-linear digital-code-to-voltage transfer applications, so as to provide the display with analog voltage signals. In such a DAC, the Gamma reference voltages as well as the corresponding digital codes are adjustable. It provides a greater degree of freedom for the realization of the correction of Gamma parameters so as to fit the curve representing the transfer function of the destination digital codes and the voltages required by the data driver and to precisely implement the digital-code-to-voltage transfer function.
    Type: Grant
    Filed: November 16, 2000
    Date of Patent: July 23, 2002
    Assignee: Industrial Technology Research Institute
    Inventors: Ming-Jiun Liaw, Yuh-Ren Shen, Chien-Chih Chen, Yong-Nien Rao
  • Patent number: 6404512
    Abstract: An image processing method and apparatus including a memory, parameter registers, and a gamma conversion processor. The memory stores at least one gamma conversion algorithm and a plurality of parameter sets corresponding to predefined gray-scale ranges. The gamma conversion processor selects a suitable parameter set from among the plurality of parameter sets according to a required output gray-scale range and transfers the selected suitable parameter set from the memory to the parameter registers sequentially. Then, the gamma conversion processor performs at a time in parallel a gamma conversion operation with respect to input gray-scale values of successive pixels of an input image data stream using the gamma conversion algorithm and the selected suitable parameter set, and generates a serial output gray-scale signal based on a result of the gamma conversion operation and the data stored in the parameter registers.
    Type: Grant
    Filed: July 6, 1999
    Date of Patent: June 11, 2002
    Assignee: Ricoh Company, Ltd.
    Inventor: Takeharu Tone
  • Publication number: 20020067435
    Abstract: Gamma correction, color saturation, tint, brightness, and contrast correction are provided for digital YUV signals by use of video hardware or software in a personal computer. The video hardware receives a digital YUV signal from a source such as a DVD player. An algorithm is empirically determined for the type of display device used to display the signal. A least-squares fit polynomial equation or a lookup table is used to determine a correction for displayed intensity by applying one or more corrections such as gamma correction, color saturation, tint, brightness, or contrast correction. The resulting image is displayed with the proper gamma for both video source and display.
    Type: Application
    Filed: December 21, 1998
    Publication date: June 6, 2002
    Inventor: MARK RAPAICH
  • Publication number: 20020063784
    Abstract: In a digital-signal-processing circuit comprising an LUT memory used for storing a gamma-correction LUT used for carrying out gamma correction on an input digital video signal and a front-stage signal-processing unit provided at a stage preceding the LUT memory and used for carrying signal processing such as contrast adjustment, after the input digital video signal having a typical width of 8 bits is subjected to signal processing such as contrast adjustment in the signal-processing unit to be transformed into a digital video signal with a width of 11 bits, the 11-bit digital video signal is supplied to the LUT memory having an output bit count of 10 bits, which is smaller than the 11-bit width of the digital video signal supplied to the LUT memory but greater than the 8-bit width of the digital video signal input to the signal-processing unit.
    Type: Application
    Filed: November 20, 2001
    Publication date: May 30, 2002
    Inventor: Hideyuki Kitagawa
  • Publication number: 20020057374
    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.
    Type: Application
    Filed: April 30, 2001
    Publication date: May 16, 2002
    Inventor: Yoshiteru Suzuki
  • Publication number: 20020051089
    Abstract: When a display image is a photographic image or a moving image, an ON signal is inputted from the ON-OFF circuit and the ON-OFF circuit to the sharpness circuit and the gamma correction circuit under a control signal from the control circuit. An inputted image signal Fc is subjected to sharpness processing for edge enhancement by the sharpness circuit, and the intermediate signal level of the image signal Fc is raised by gamma correction of the gamma correction circuit. Thus, the CRT can display a sharp, high-quality photographic or moving image having an enhanced edge and emitting light with its luminance proportional to the signal level. When a display image is a code display image of letters or the like, the sharpness circuit is controlled to be in an unactivated state and the gamma correction circuit is controlled to be in an activated state under a control signal from the control circuit.
    Type: Application
    Filed: May 1, 2001
    Publication date: May 2, 2002
    Inventors: Akira Arimizu, Shigeto Nishijima
  • Publication number: 20020036716
    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.
    Type: Application
    Filed: March 12, 2001
    Publication date: March 28, 2002
    Inventors: Keiichi Ito, Atsuhisa Kageyama, Nobutaka Okada, Katsuya Ishikawa, Hidetoshi Suzuki, Hisao Kunitani, Yuki Kakuya
  • Patent number: 6359663
    Abstract: Method and apparatus for the conversion or generation of a video signal intended to be displayed on an image display with different luminance response times for rise and decay. The conversion or generation of the video signal is so that motion artifacts which are caused by the difference in luminance response times for rise and decay such as large area luminance jumps, large-area flicker and faulty temporary large-area luminance are fundamentally cancelled in the displayed image.
    Type: Grant
    Filed: December 14, 1999
    Date of Patent: March 19, 2002
    Assignee: Barco N.V.
    Inventors: Koen Gadeyne, Patrick Vandenberghe
  • Patent number: 6344857
    Abstract: A gamma correction circuit includes a node level setting unit set predetermined level values of video signals from outside, in a case where encoded M-bit (where M is an arbitrary integer) video signals being represented by using predetermined number of sections and the level values of the video signals corresponding to 2n+1 number of nodes (where n is an arbitrary integer) associated with the sections on which the node are specified, and a gamma correction unit for executing gamma correction for the M-bit video signal in accordance with the level values of the nodes set in the node level setting unit, thereby the gamma correction circuit executes gamma correction on various types of display devices.
    Type: Grant
    Filed: April 1, 1999
    Date of Patent: February 5, 2002
    Assignees: Hitachi, Ltd., Hitachi Video & Information System, Inc.
    Inventors: Takaaki Matono, Haruki Takata, Katsunobu Kimura, Tatsuo Nagata, Takeshi Sakai, Koichi Sudo
  • Patent number: 6340996
    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.
    Type: Grant
    Filed: October 5, 1999
    Date of Patent: January 22, 2002
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Takahiro Nakamura
  • Publication number: 20010048476
    Abstract: Of three-color signals R′, G′ and B′, obtained as output signals of multipliers 156R, 156G and 156B, designed to effectuate luminance compression of the three-color signals R, G and B sent to input terminals 151R, 151G and 151B by multiplying the signals R, G and B with a coefficient k, in such a manner as to maintain saturation and color hue of the three-color signals R, G and B, only the saturation of color video signals represented by the three-color signals R′, G′ and B′ is compressed by first saturation compression circuits 160R, 160G and 160B so that the signal level of the signal of the three-color signals R′, G′ and B′ having the highest signal level will be the clip level.
    Type: Application
    Filed: January 5, 1999
    Publication date: December 6, 2001
    Inventors: HITOSHI NAKAMURA, SEIJI KAWA, FUMIHIKO SUDO
  • Patent number: 6317157
    Abstract: The present invention introduces an image conversion apparatus capable of coinciding the luminance variation ratio in the display unit of the television receiver with a variation ratio according to the linear operation though the linear operation is applied to the video signal outputted from the computer. The first &ggr; correction circuit receives the video signal outputted from the computer. This video signal intends to be inputted to a CRT display unit, therefore, the video signal is provided with an inverse &ggr; property corresponding to the luminance property of the CRT display unit. The first &ggr; correction circuit 100 applies the &ggr; correction operation to the video signal so as to remove the inverse &ggr; property in the video signal. The linear arithmetic circuit applies the linear operation to the output from the first &ggr; correction circuit.
    Type: Grant
    Filed: April 28, 1998
    Date of Patent: November 13, 2001
    Assignee: Fujitsu Limited
    Inventor: Akinoli Takayama
  • Patent number: 6313884
    Abstract: A gamma correction circuit includes an amplifier (A) coupled to receive an input signal (Vi), and a non-linear impedance (Rg) coupled to the amplifier (A) for determining a gain of the gamma correction circuit in such a manner that the gain increases when the input signal (Vi) increases.
    Type: Grant
    Filed: April 1, 1998
    Date of Patent: November 6, 2001
    Assignee: U.S. Philips Corporation
    Inventor: Tony P. Van Endert
  • Patent number: 6304300
    Abstract: The present invention provides a method, a device, and a system for performing gamma correction on a set of pixel data based on a gamma correction curve table. The gamma correction curve table includes a specified total number of intensity levels associated with gamma corrected pixel values with one intensity level per pixel value. The method includes partitioning the gamma correction curve table into N segments such that each of the N segments is associated with a set of intensity levels from the specified total number of intensity levels. A plurality of intensity levels is selected for each of the N segments such that significant banding effects are not visible to the human eye between an adjacent pair of the selected intensity levels. The gamma corrected pixel values are stored for each of the N segments such that each of the plurality of selected intensity levels functions as an index to the associated gamma corrected pixel values.
    Type: Grant
    Filed: November 12, 1998
    Date of Patent: October 16, 2001
    Assignee: Silicon Graphics, Inc.
    Inventors: David S. Warren, Andrew D. Bowen, David L. Dignam
  • Patent number: 6295098
    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.
    Type: Grant
    Filed: July 6, 1999
    Date of Patent: September 25, 2001
    Assignee: Sony Corporation
    Inventors: Hitoshi Motonakano, Shozo Mitarai, Akira Arimizu
  • Patent number: 6292165
    Abstract: An adaptive piece-wise approximation method for gamma correction is disclosed. The method includes an adaptive way for segmenting the brightness intensity input range and after the segmentation, a set of selected sampling points is taken. A simplified gamma correction circuit is then designed to omit the subtraction and the division calculation in the gamma correcting function by choosing the segmentation points appropriately. The improved gamma correction circuit comprises a multiplexer, a subtractor, an offset block, a multiplier, a division block, and an adder. An intensity signal at the set of selected input points is sampled and the sampled values are stored in providing a top value and a bottom value for the video intensity value to be gamma corrected. The video intensity value is then sent into the gamma correction circuit to get a gamma corrected data word representing pixel intensity for its respective input video intensity value.
    Type: Grant
    Filed: August 13, 1999
    Date of Patent: September 18, 2001
    Assignee: Industrial Technology Research Institute
    Inventors: Tsu-Ping Lin, Han-Min Cheng, Chen-Pan Kung
  • Patent number: 6281944
    Abstract: An apparatus for correcting a non-linear characteristic in a display device to keep the number of displayable colors as it is and to unify a picture quality for each product. In the apparatus, a bias voltage to be applied to a digital to analog converter converting a digital image signal into an analog image signal is changed in accordance with a logical value of the digital image signal. Accordingly, the apparatus generates an analog image signal in which the non-linear characteristic in the display device is compensated.
    Type: Grant
    Filed: August 11, 1998
    Date of Patent: August 28, 2001
    Assignee: LG Electronics Inc.
    Inventor: Han Jin Kim
  • Patent number: 6278496
    Abstract: In the &ggr; correction circuit, a crossover point arithmetic processing unit performs arithmetic processing for each region on crossover points y in the output data direction of a &ggr; correction crossover line based on a plurality of slope data A respectively specified for each of a plurality of regions and crossover point positions X in the input data direction set in advance.
    Type: Grant
    Filed: October 8, 1998
    Date of Patent: August 21, 2001
    Assignee: Sanyo Electric Co., Ltd.
    Inventors: Makoto Kitagawa, Mitsugu Kobayashi, Makoto Fujioka, Yusuke Tsutsui, Hisao Uehara
  • Patent number: 6271891
    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.
    Type: Grant
    Filed: June 18, 1999
    Date of Patent: August 7, 2001
    Assignee: Pioneer Electronic Corporation
    Inventors: Shuji Ogawa, Hirofumi Kawaguchi, Nozomu Kikuchi, Junichi Usui, Masayuki Takeda
  • Patent number: 6266103
    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.
    Type: Grant
    Filed: June 26, 2000
    Date of Patent: July 24, 2001
    Assignee: Da Vinci Systems, Inc.
    Inventors: Nicholas Barton, Sanjay Devappa Rai, Xueming Henry Gu
  • Publication number: 20010008429
    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.
    Type: Application
    Filed: January 17, 2001
    Publication date: July 19, 2001
    Applicant: Sony Corporation
    Inventor: Akira Arimizu
  • Patent number: 6215529
    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
    Type: Grant
    Filed: March 5, 1998
    Date of Patent: April 10, 2001
    Assignee: Matsushita Electric Industrial Co. Ltd.
    Inventors: Hiroko Sugimoto, Atsuhisa Kageyama, Masahiro Takeshima, Minoru Kawabata
  • Patent number: 6184852
    Abstract: A processing system for a spatial light modulator in the form of an array of defomable mirror devices receives a gamma-corrected, video input signal. A de-gamma processor removes all or part of the gamma-correction of the video input signal to match the data to the form of the spatial light modulator.
    Type: Grant
    Filed: September 10, 1999
    Date of Patent: February 6, 2001
    Assignee: Digital Projection Limited
    Inventors: John David Millward, John Gillespie
  • Patent number: 6166781
    Abstract: A non-linear response correction apparatus and method reduce look up table size and output error. In one embodiment, a range of an N-bit input signal is split into two or more sectors, based on a gradient of a non-linear correction curve and an allowable error, and then a N-bit input signal is divided into U upper bits and D lower bits where U and D depend on which sector contains the input signal. First and second look up tables read first and second data stored therein, respectively, using the upper bits of the digital signal as an address. The first data is the difference between a corrected signal and the input signal, and the second data is the gradient of the corrected signal with respect to the gradient of the input signal. The second data read from the second look up table is multiplied by the lower bits, and the first data read from the first look up table is added to the upper bits.
    Type: Grant
    Filed: October 3, 1997
    Date of Patent: December 26, 2000
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Mal-seob Kwak, Jun Sunwoo, In-jun Hwang, Bong-soon Kang
  • Patent number: 6160532
    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.
    Type: Grant
    Filed: March 12, 1998
    Date of Patent: December 12, 2000
    Assignee: Seiko Epson Corporation
    Inventors: Chiharu Kaburagi, Takashi Kurumisawa, Takahiro Sagawa
  • Patent number: 6137543
    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.
    Type: Grant
    Filed: December 19, 1997
    Date of Patent: October 24, 2000
    Assignee: LG Electronics Inc.
    Inventor: Hee Chul Kim
  • Patent number: 6137542
    Abstract: A circuit for gamma correcting a video signal incorporates both linear approximation as well as a look-up table, in which the disadvantages of linear approximation, i.e., inaccurate representation of the gamma function, and of a gamma look-up table, i.e., low resolution at low grey levels, are minimized. The transfer function of the look-up table is chosen such that the inaccuracies of the linear approximation are compensated.
    Type: Grant
    Filed: December 21, 1998
    Date of Patent: October 24, 2000
    Assignee: Phillips Electronics North America Corporation
    Inventor: Johannes G. R. Van Mourik