Abstract: A method for luminance transition improvement includes the following steps: inputting an image comprising a plurality of pixels comprising a first pixel; generating an extreme gray level according to the plurality of pixels; generating a first gray level difference according to the gray level of the first pixel and the extreme gray level; generating a first gray level adjustment value according to the first gray level difference, a first weighted value, a second weighted value, and a first order differential value of the gray level of the first pixel relative to a spatial coordinate; and generating an adjusted gray level of the first pixel according to the first gray level adjustment value and the gray level of the first pixel.

Abstract: In a method of expressing a gray level of a high load image and an apparatus for driving a Plasma Display Panel (PDP) using the method, a load ratio of the input image signal is calculated, and an error diffusion of a lower bit of gray level data corresponding to the input image signal is performed when it has been determined that the calculated load ratio is greater than or equal to a critical load ratio which is a lowest load ratio among the load ratios in which luminance at every gray level does not increase while the gray level increases at a low gray level area. The error-diffused gray level data is then displayed on the PDP.

Abstract: An improved method for color transient enhancement in an input video frame of pixels. The luminance value of a current pixel is compared to that of neighboring pixels. A correction value is determined and the chrominance value of the current pixel is “pushed” towards the neighboring pixel that has a luminance value closest to that of the current pixel, by adding the correction value to the current pixel's chrominance value. The original video frame is also separately processed using a CTI method, and the current pixel's corrected chrominance value is combined with the corresponding pixel in the output of the CTI processing by soft switching unit to generate an output video frame that is an enhanced version of the input video frame.

Abstract: A superior Color Transient Improvement technique is adaptive to the local image features, so that more natural color edge transition improvement can be accomplished. A gain control function is provided that depends on the local image feature so that different regions of the image can be treated differently. Further, a correction signal is controlled in such a way (by the local image feature) that neither undershoot nor overshoot occurs, eliminating the need for post-processing for undershoot/overshoot removal.

Abstract: A method and apparatus for improving the transition characteristic of a chrominance signal. The method and apparatus generate an edge-improved chrominance signal using a differential signal of a luminance signal and a differential signal of the chrominance signal and generate a transition-improved chrominance signal by removing an undershoot and overshoot of the edge-improved chrominance signal.

Abstract: A method of color saturation compensation in a video signal is disclosed. The method includes the steps of: processing a luminance signal component of the video signal; determining whether the processing of the luminance signal results in a change in chrominance saturation; if the step of determining reveals that the chrominance saturation has changed, applying a chrominance compensation signal to the chrominance signals to counteract the effects of chrominance saturation, wherein the step of applying a compensation signal include the steps of: generating a compensation signal which is dependent on hue and luminance ratio (output luminance signal/input luminance signal). Apparatus for performing the method is also disclosed.

Abstract: A display has a screen which incorporates a light modulator. The screen may be a front projection screen or a rear-projection screen. Elements of the light modulator may be controlled to adjust the intensity of light emanating from corresponding areas on the screen. The display may provide a high dynamic range.

Abstract: This invention corrects chrominance misalignment that occurs during chrominance down-sampling and up-sampling. The invention extracts a binary index from the corresponding luminance signal. The binary index enables generation of a filter window. On down-sampling the filter window is applied to a block of source chrominance pixels which are filtered or not based upon the binary index. On up-sampling the binary index of the filter window for the target chrominance pixels determines which are filtered or not.

Abstract: At first, average brightness of each of frames of a moving image is calculated by a computer. Following that, a moving average along a time axis is calculated for each of the frames so that moving average brightness is generated as a reference data of brightness. Next, difference data between the average brightness and the moving average brightness are generated. Further, the difference data are grouped based on the signs of the reference data. Then, on the basis of the grouped difference data, it is judged whether an unwanted change of brightness is present. Thus, it is automatically and precisely judged whether the unwanted change of brightness such as a flicker is present in the moving image.

Abstract: A control signal (k_lum) derived from the luminance component (Y) of a video signal is used to adaptively control a temporal noise reduction filter (10) according to the level of motion in a video image. To compress the control signal for storage in a memory (30), the control signal is averaged over each 2×2 pixel area, and then a non-linear compression function is applied. The non-linear compression function preferably selects quantization values of the control signal which correspond to a perceptually substantially linear response in the noise reduction factor (NRF) of the noise filter (10).

Abstract: A method and system for correcting luma data and chroma data from a composite signal for a plurality of lines are disclosed. The method and system include correlating line data of the composite signal from a portion of the plurality of lines to provide a plurality of correlation signals. The method and system also include generating a chroma suppression signal based on the plurality of correlation signals. The chroma suppression signal indicates whether to suppress a portion of the chroma data. The chroma suppression signal indicates that the portion of the chroma data should be suppressed when a large luma transition and the chroma data being beneath a threshold are detected.

Abstract: This invention corrects chrominance misalignment that occurs during chrominance down-sampling and up-sampling. The invention extracts a binary index from the corresponding luminance signal. The binary index enables generation of a filter window. On down-sampling the filter window is applied to a block of source chrominance pixels which are filtered or not based upon the binary index. On up-sampling the binary index of the filter window for the target chrominance pixels determines which are filtered or not.

Abstract: A method of mapping an input color gamut of an input device onto an output color gamut of an output device includes establishing a threshold chroma value in the input color gamut. For first input chroma values below the threshold chroma value, each first input chroma value is mapped onto a respective one of a plurality of first output chroma values such that a first linear relationship exists between the first input chroma values and the first output chroma values. Each corresponding first input lightness value is mapped onto a respective one of a plurality of first output lightness values such that a second linear relationship exists between the first input lightness values and the first output lightness values. For second input chroma values above the threshold chroma value, each second input chroma value is mapped onto a respective one of a plurality of second output chroma values such that a first non-linear relationship exists between the second input chroma values and the second output chroma values.

Abstract: A system and method for enhancing resolution in a video image includes acquiring a relatively low resolution video signal and applying a peaking function and analyzing the peaked signal to identify potential edges. The low resolution signal is then upconverted to a higher resolution format. Actual edges in the image are detected and linked in the higher resolution format, and a luminance transition improvement function is applied to the edges to sharpen the image. Analysis of the image while at low resolution reduces computation time, yet still produces a high quality output image.

Abstract: A method for smoothing a digital color image having color pixels in which each colored pixel is expressed as one luminance and two chrominance color values, including computing parameters for at least two orientations for each pixel in the stored digital image; using the computed parameters to form a classifier value for each such orientation and using such classifiers to determine the pixel classification based on such classifiers; and smoothing pixel chroma values according to the determined pixel classification.

Abstract: A method for processing saturated video intervals in a video sequence. The method either removes or retains the saturated interval. If the interval is removed, the sequence is altered to accommodate the removal. The accommodation is either complete elimination, substitution of a derived interval, or substitution by repeating adjacent intervals. If the interval is retained, information is extracted while limiting the effects of the saturation. The interval can either be encoded with lower data rates, with increased data rates being applied to subsequent intervals, the temporal prediction encoding can be forced to a B interval, an I interval can be inserted, or the sequence restarted, or a coupled encoder decoder system can be set up that uses the same transform and clipping steps to limit the effects of saturation.

Abstract: An improved method for color transient enhancement in an input video frame of pixels. The luminance value of a current pixel is compared to that of neighboring pixels. A correction value is determined and the chrominance value of the current pixel is “pushed” towards the neighboring pixel that has a luminance value closest to that of the current pixel, by adding the correction value to the current pixel's chrominance value. The original video frame is also separately processed using a CTI method, and the current pixel's corrected chrominance value is combined with the corresponding pixel in the output of the CTI processing by soft switching unit to generate an output video frame that is an enhanced version of the input video frame.

Abstract: A video signal processor is provided to receive a luminance signal, a color-difference signal, and a color signal. The processor comprises a circuit for calculating a low-frequency component of the luminance signal, a circuit for calculating a low-frequency component of the color-difference signal, and a circuit for extracting a high-frequency component of the color signal. The processor also comprises a division circuit, a multiplication circuit, and an addition circuit. In the division circuit, the low-frequency component of the color-difference signal is divided by the low-frequency component of the luminance signal, and in the multiplication circuit, an output signal from the division circuit is multiplied by the high-frequency component of the signal extracted, a multiplied signal being outputted as a correction signal for the color signal. In the addition circuit, the correction signal is added to the color signal.

Abstract: There is disclosed an apparatus for sharpening an edge in a video image. The apparatus comprises: 1) a first circuit for determining a first luminance value of a first pixel associated with the first edge and a second luminance value of a second pixel associated with the first edge, wherein the first and second pixels are adjacent pixels; 2) a second circuit for determining a position of a first subpixel disposed between the first and second pixels, wherein the first subpixel position is disposed approximately at a center of the first edge; 3) a third circuit for increasing a luminance value of a second subpixel disposed on a first side of the first edge center; and 4) a fourth circuit for decreasing a luminance value of a third subpixel disposed on a second side.of the first edge center opposite the first side.

Abstract: A color modification system and method for reducing the number of computations performed on a pixel color. This reduction in computations increases the rate at which color modification may be performed and decreases the effects of rounding errors. Decreasing the effects of rounding errors produces a more accurate color modification, thereby reducing the likelihood of artifacts. The system and method performs color modification on a pixel color, where the color includes a first, second, and third component and each component defines a value of the color. The system includes a chroma lookup table having a plurality of entries. Each entry corresponds to a luma value and contains chroma coefficients. The chroma coefficients define color modifications to be applied to the components of the color. If a luma value is received, the chroma lookup table generates output chroma coefficients at an output.

Abstract: The present invention provides a color difference signal correction apparatus for correcting color difference of parts having no color, particularly white characters, which can make the correction with high accuracy also for images including lightly colored parts.

Abstract: In an image enhancement method and circuit, a luminance signal is extracted from input color signals. Histogram equalization is performed using a cumulative density function of the extracted luminance signal which is input in a screen unit. A transform function is controlled to map a mean level of the extracted luminance signal to itself, so that an adjusted luminance signal is output. The color signals are varied according to the variation of the luminance signals to output compensated color signals. Thus, image contrast is enhanced, and an undistorted color signal is provided at the same time. In order to reduce the hardware of the circuit, an interpolated cumulative density function is obtained by interpolating a quantized cumulative density function of an input luminance image and is used as a transform function. The transform function is controlled to map a mean level of the input luminance image to itself.

Abstract: A video frame is decomposed into blocks of pixels. Blocks that contain moving edges are not processed further. The remaining blocks are examined for the likelihood of having color bleeding artifacts, and not processed further if the likelihood is low. The likelihood is determined by examining statistics of the chrominance values. The remaining blocks are de-color bleeding filtered at the chrominance plane, without affecting the corresponding luminance plane.

Abstract: A color saturation correction method is provided that, by means of a simple circuit configuration, can reduce dissimilarities in picture quality between images that are projected from film and images obtained from video signals, caused by over-saturation of colors in dark scenes. The luminance signal level of a video signal is detected and the saturation of colors in dark portions is then corrected by reducing the chrominance signal level depending on a luminance signal level when the luminance signal level is at or below a predetermined level. The luminance level at which adjustment starts is preferably set to 50% or lower, and the chrominance signal output gain is preferably −3 dB or greater.

Abstract: A technique for differencing an image is disclosed. In one embodiment, the technique is realized by measuring light values in a scene to generate a first image and a second image. The first image is separated into first luminance and chrominance components, and the second image is separated into second luminance and chrominance components. A difference is determined between the first and the second luminance components to generate a luminance mask. Similarly, a difference is determined between the first and the second chrominence components to generate a chrominance mask. The luminance mask and the chrominence mask are combined to determine a difference between the first and the second images.

Abstract: A color modification system and method for reducing the number of computations performed on a pixel color. This reduction in computations increases the rate at which color modification may be performed and decreases the effects of rounding errors. Decreasing the effects of rounding errors produces a more accurate color modification, thereby reducing the likelihood of artifacts. The system and method performs color modification on a pixel color, where the color includes a first, second, and third component and each component defines a value of the color. The system includes a chroma lookup table having a plurality of entries. Each entry corresponds to a luma value and contains chroma coefficients. The chroma coefficients define color modifications to be applied to the components of the color. If a luma value is received, the chroma lookup table generates output chroma coefficients at an output.

Abstract: An image processing apparatus includes a data dividing section for dividing digital data into a plurality of blocks of data. A first parallel shift control section controls, block by block, first parallel shift for shifting the blocks of digital data to positions coinciding with an angle of rotation of an image. A second parallel shift control section subdivides the digital data in each of the blocks into subblock data, and controls second shift for shifting the subblock data in each block to positions coinciding with the angle of rotation of the image such that a color image is correctly displayed. The apparatus is capable of rotating a color image correctly and rapidly with a simple circuit arrangement.

Abstract: An edge achromatization circuit and method is disclosed wherein, in digital camera signal processing, a signal having a linear characteristic before &ggr; correction is performed to suppress a color component of an edge portion while keeping a luminance. The edge achromatization circuit includes a luminance signal operation matrix circuit for converting R, G, B signals before &ggr; correction is performed therefor into a luminance signal, an edge detection circuit for extracting an edge signal from the luminance signal, an absolute value operation circuit for converting the edge signal into an absolute value, a multiplier for controlling the gain of the absolute value, subtractors for obtaining color difference signals from the R, G, B signals and the luminance signal, multipliers for multiplying the color difference signals and an output coefficient, and subtractors for arithmetically operating results of the multiplication and the R, G, B signals to obtain R′, G′, B′ color signals.

Abstract: The invention provides an improved method and system for presenting color television signals. Television signal chrominance values for foreground elements are adjusted in response to television signal chrominance values for background elements, so as to minimize display artifacts while preserving the relative color contrast between foreground and background. (1) The invention modifies I and Q values of the foreground color to reduce the difference of the foreground I and Q with respect to the background I and Q. (2) The invention modifies Y, I and Q values of the foreground color to avoid colors known to display poorly for selected output devices. (3) The invention modifies Y values of the foreground color to maintain intended visual contrast between foreground and background colors. (4) The invention modifies Y, I and Q values of the foreground color to decrease cross-luminance separation artifacts at the border between foreground and background colors.

Abstract: A method and apparatus for electronically processing video signals representing images of an object or scene so that details of some portion or all of the object or scene are enhanced in the video display reproduction of the images. Video image signals from a video camera are processed to derive digital color-representative signals and a digital luminance signal, and the luminance signal is filtered to remove higher spatial frequency components. The resulting low pass digital data is subtracted from the original luminance image data, leaving digital data representing the high-pass image components. The high-pass image digital data is passed to an amplification stage where all or only selected pixels are amplified by a factor that varies as a function of the low-pass data value of those pixels and by the location of the pixels within the image. This enables different degrees of enhancement of the light and dark areas of the image.

Abstract: An image display apparatus is provided for reducing occurrences of moving image false-edges by preventing profound changes in “on”/“off” subfield distribution, and for displaying a sharp image that does not appear blurred. This is achieved by effectively dividing one TV field and by displaying a gray level of an input image signal using an “on”/“off” subfield combination, out of possible “on”/“off” subfield combinations for displaying the gray level, in which a number of subfields with large luminance weightings that are “on” is minimized.

Abstract: A method is proposed for processing transitional regions in a picture signal. The picture signal comprises a sequence of digital pixel values. A number of adjacent pixel values, which contain a processing pixel value, are combined to form a processing block. A corrected pixel value is calculated for the processing pixel value. The maximum and minimum pixel values are first determined in the processing block to define the transitional region. The transitional region is then split into a number of sections on the basis of the magnitude of pixel value. Finally, a determination is made as to the section in which the processing pixel value is located. The processing pixel value is allocated a corresponding correction value in order to increase, to reduce or to leave unchanged the processing pixel value, in accordance with a predetermined transfer function.

Abstract: This invention relates to the color matching function used in connection with the luminance or white stretch function in a television video processor. Automatic adjustment in the amplitude of the color difference signals is provided to compensate for the effect of the stretch of the luminance signal in a provision called color matching. The general principal of color matching being, any percentage change in the amplitude of the luminance signal due to the white stretch effect, must be balanced by the same percentage changes in the color difference signal so that the ratio of the color signals can be maintained after matrixing. This accomplished by compensating the color difference signals by a varying amount that decreases with increasing the input luminance signal level when the level of the input luminance signal is above said selected threshold.

Abstract: A system and method for compensating against false color from composite video source information detects when there is a diagonal luminance transition (or a cross pattern) and attenuates combed chrominance information to facilitate a reduction in a false coloring effect. A programmable threshold diagonal transition detector generates a multi-level compensation control signal, such as the amount of chrominance reduction or attenuation (in dB) to effectively notch combed chrominance data, based on a detection of a diagonal transition of luminance data among lines of video data. The multi-level compensation control signal is used by a multi-level compensator to attenuate the combed chrominance information from the 2-D adaptive comb filter.

Abstract: In a method of enhancing a quality of a video signal (Yin), an absolute value (ST) of a first derivative of the video signal (Yin) is obtained (51-59), and the video signal (Yin) is processed (53-57, 61-69) in dependence upon the absolute value (ST) of the derivative of the video signal (Yin).

Abstract: A method and arrangement for steepening the edges of a color signal, in which a control signal is generated which is obtained by differentiation, rectification and subsequent differentiation of the rectified first differentiation, and is temporarily assigned to the color signal, and in which, in dependence upon the control signal, chrominance values of reference pixels of the color signal are copied on edge pixels of the color signal in such a way that the chrominance values of reference pixels preceding the edge pixels are copied on the edge pixels in the case of a positive control signal and the chrominance values of reference pixels following the edge pixels are copied on the edge pixels in the case of a negative control signal, false chrominance values of pulses which are steepened are prevented in that a chrominance value of a reference pixel is copied on an edge pixel only when the values of the control signal in the assigned region between the reference pixel and the edge pixel do not have a zero cross

Abstract: In a method of obtaining an improved perceived color transient, an artificial transient signal is inserted (50) into a luminance signal (Yin) when it is detected (10, 20, 30) that there is an edge in a chrominance signal (Cin) in the absence of an edge in the luminance signal (Yin).

Abstract: A method for improving chromatic text resolution includes transforming a color image signal into chrominance (C1, C2) image signal components and a luminance (L) image signal component. A mask is created for a selected image object from the luminance image signal components. The C1 and C2 image signal components are modified by the mask into new image signal components, C1.sub.NEW, C2.sub.NEW, respectively. The new image signal components are transformed, with L, into a new color image signal that does not have chromatic blur.

Abstract: An image processing system 20 comprises a format converter 21 for receiving a first signal having a larger bandwidth and a second signal having a smaller bandwidth, the first and second signals together representing an image. A processor 23 is arranged to process the first and second signals to produce signals representing a manipulated version of the image. The system further comprises a deriving circuit 25 which is arranged to derive from information in the larger bandwidth signal additional information for the smaller bandwidth signal. The deriving circuit derives an unknown value of a pixel as represented by the smaller bandwidth signal from known values of the pixel and the pixels adjacent thereto as represented by the larger bandwidth signal and from known values of the adjacent pixels as represented by the smaller bandwidth signal. The deriving circuit facilitates conversion of the first and second signals into another signal format representing the image.

Abstract: A system and method for eliminating luminance false contours within rendered documents by sacrificing chrominance accuracy within printer halftones and for using the reduction of chrominance to improve the luminance correctness for any requested color. Ordinary halftone processes are modified such that small hue shifts are traded off for the ability to eliminate luminance false contours. Luminances of colored inks are created in a manner that turns on only one color spot at a time, instead of all three, within a slowly changing gray area because numerically equivalent steps in chrominance are much less visible in printed form than changes in luminance. Removal of false contours is therefore achieved by chrominance variations rather than by spatial variations in a document.

Abstract: (1) The analog or digital components (such as RGB, Y/I/Q, Y/U/V, Y/R-Y/B-Y, Y/Cr/Cb, etc.

Abstract: A circuit for enhancing chrominance transitions in a received chrominance video signal comprises a linear-phase digital filter supplied with an input stream of discrete chromatic image elements. The filter also has a high-pass transfer characteristic in a region of the frequency spectrum corresponding to an upper limit of a transmitted chrominance signal bandwidth for enhancing high-frequency components of the received chrominance signal. The circuit additionally includes non-linear digital post-processing circuitry which accepts as input an output of the filter and the input stream of discrete chromatic image elements. The non-linear post-processing circuitry acts on the output of the filter to eliminate distortions introduced in the received chrominance signal by the filter. The post-processing circuitry then detects if the received chrominance signal contains a transition pattern corresponding to predetermined patterns.

Abstract: A Y/C separation apparatus separating a luminance signal and a chrominance signal from a composite color television signal includes a high band level detection circuits for detecting a high band level of each input signal and a judge circuit for controlling Y/C separation and selects one of filters to pass the input signal according to the high band levels detected by the high band level detection circuits and controls a separated chrominance signal component. As a result, when the high band level is small, a horizontal BPF is selected and even when the input signal is a black or white video signal without chrominance signal, dot interference is not conspicuous.

Abstract: A method which can be used to enhance an outline of an image displayed in an image display apparatus such as a television receiver, and a circuit performing the method. The circuit includes a peaking signal generation circuit which generates a first peaking signal and a second peaking signal corresponding to an amplitude transition of a video signal. A first peaked video signal generation circuit generates a first peaked video signal by adding the first peaking signal to the video signal. A control signal generation circuit generates a first control signal based on a result of comparing a first-order differential signal developed by differentiating the video signal with a reference signal, and a second control signal by delaying the first control signal for the predetermined period. A first selection circuit selects either the video signal or the first peaked videos signal according to the first control signal.

Abstract: A video signal processing apparatus includes an equalizer for delaying an input color signal by an adjustable phase retardation. A low pass filter is operative for delaying the input color signal by an adjustable phase retardation. A phase detector is operative for detecting a difference between a phase of an output signal of the equalizer and a phase of an output signal of the low pass filter, and outputting a signal representative of the detected phase difference. The phase retardation provided by the equalizer and the phase retardation provided by the low pass filter are adjusted in response to the output signal of the phase detector to maintain the difference between the phase of the output signal of the equalizer and the phase of the output signal of the low pass filter at a predetermined value, for example, 90 degrees.

Abstract: The 25 Hz offset present in the subcarrier frequency of the PAL television standard causes residual and phase modified subcarrier to be left on the luminance signal, which can produce undesirable visual artifacts in the picture. In order to filter luminance therefore without loss of resolution, an adaptive luminance filtering process and structure are provided. Due to the wide range of sample frequencies that must be dealt with, there are e.g. three separate filters available selectable under software control depending on the particular video standard being filtered, i.e. for various of the of NTSC and PAL television standards. The adaptive notch filter is switched on during times of low video transitions and is by-passed during high video transitions, thus avoiding loss of resolution during the high video transitions.

Abstract: An automatic aspect ratio discrimination apparatus for detecting a picture starting position, a picture ending position and a subtitle ending position by generating three histograms segmented by two slice levels S and T at every line from a luminance signal Y at a comparison circuit and counters, judging when the line is black, a picture or a subtitle by inputting the obtained histograms to the comparison circuit, detecting lines varying from black to picture, from picture to black, and from subtitle to black at an edge detection circuit and judging if the lines varying from black to picture and from picture to black are stable in time or not at a temporal filter.

Abstract: A device for filtering video images, of the type which includes first and second circuit portions, each having first and second input terminals respectively adapted to receive digitalized luminance and chrominance components of a television signal, and an output terminal coinciding with an output terminal of the device. The first and second circuit portions further include first, second and third filters, cascade coupled to one another, and a fourth filter, respectively.The first, second and third filters incorporate a computational circuit which uses a logic of the fuzzy type to process the digitalized luminance component. The fourth filter includes a computational circuit which processes the digitalized chrominance components based upon a parameter supplied from the second filter.

Abstract: In a high definition flying spot telecine, noise from photomultiplier tubes and afterglow correctors reaches unacceptable levels at high frequencies. The circuit illustrated applied a conventional gamma correction to low frequency components (at 32) but applies a non-linear characteristic to the high frequency components (at 36). The characteristic is chosen to provide the optimum noise performance for positive or negative film. The two parts of the signal are then recombined by adders 40. High frequency processing is carried out on a multiplex of the R, G and B components to reduce complexity (at 16).

Abstract: A method and apparatus which allows different amounts of filtering to be applied to specific parts of a foreground image, thus minimizing visible noise in the backing area, while preserving fine detail information of foreground objects. The method and apparatus identify three areas within the foreground, namely unobscured backing (screen) area, screen to foreground subject transition area, foreground subject area. The area where full amount of filtering is desired is the backing area, including shadows. This is the area where the background image will be added, and if noise is present in this area, it will be added to the background image. The transition area from the screen to the foreground object requires variable amounts of filtering, depending on the width of the transition. For sharply focused edges and very fine detail, the transition width is very small, and any filtering applied there will cause blurring and softening of these edges and details. Therefore, no filtering is applied to those areas.