151 results about "Tone reproduction" patented technology

An image desired to be reproduced is scanned to determine its video pixel grey values. A histogram generator generates a histogram distribution representing a frequency of the grey values. The histogram distribution is analyzed to determine a minimum and maximum input grey values which define input boundaries. A segment point is computed between the input boundaries based on the histogram data. The segment point defines a plurality of input segments between the input boundaries. A dynamic output range is selected. Each input segment is mapped to an output segment based on a linear transformation for the corresponding segment. In this manner, a tone reproduction curve map having a piecewise linear transformation is automatically generated from the image histogram data.

Defects in an image forming system may give rise to visible streaks, or one-dimensional defects in an image that run parallel to the process direction. One known method for compensating for streaks introduces a separate tone reproduction curve for each pixel column in the process direction. A compensation pattern according to this invention has a plurality of halftone regions that are lead by, trained by, and separated by rows of fiducial marks. The fiducial marks allow the printer pixel grid and a scanning pixel grid to be correlated. The gray level in each pixel column of each gray level portion is measured and analyzed to produce a local tone reproduction curve for each pixel column and associated line width. The local tone reproduction curves are then used to compensate for the streak defect when printing.

A method of automatic mapping of image data includes representing image data for an image as luminance values, determining a key value as a function of an average luminance value of the image and of minimum and maximum luminance values of the image, generating offset-adjusted luminance values including applying an offset to each of the luminance values, the offset being a function of the determined key value, and computing a tone reproduction curve for at least a region of the image which includes applying a mapping function to the offset-adjusted luminance values.

Features, such as finely controlling toner response curves and properly orienting documents, provided by imaging capturing devices are accessed through a complicated graphical user interface that includes a number of tabs and large number of dropdown boxes, pop-up boxes, drop-down menus, and the like. Various displayable portions of a scanner control graphical user interface include a task-specific user instruction access button. Selecting the task-specific user instruction access button causes a pop-up menu to be displayed listing tasks that can be accomplished using, at least in part, various ones of the control elements displayed in the currently displayed portion of the scanner control graphical user interface. Upon selecting a selectable task item in the pop-up menu, a task-specific user instruction graphical user interface is displayed. A task instruction portion of the task-specific user instruction graphical user interface, provides the user with detailed instructions for accomplishing the selected task. A related tasks portion provides the user with a list of selectable tasks related to the selected task. The task description in the task instruction portion includes selectable terms used in the task description. Selecting a selectable term allows the user to either access the help entries on the selected term and / or causes a new list of selectable tasks to be displayed in the related tasks portion.

Compensation for rendering device non-uniformities is provided for halftoned images. A spatially dependent tone reproduction curve (TRC) provides compensation values. Pixel location information is used to access TRC values. For example, the values are modification values. The modification values are added to the pixel values to generate combined values. Quantization is applied to the combined values to prepare compensated image data for rendering. For example, Rank Ordered Error Diffusion is applied to the combined values. The combined values may include diffused error from previously processed pixels. Gray values may be estimated for the respective pixels. The estimated gray values may be used to access compensation information from a TRC that is both spatially and gray value dependent. Mathematical basis decomposition is used to reduce TRC memory requirements. For example, Discrete Cosine Transformation, Singular Value Decomposition or Principal Component Analysis is used to determine a compact form for the TRC.

The method and system for printer color calibration use a combination of a full-width array (FWA) or similar page-scanning mechanism in conjunction with an spectrophotometer color measurement system in the output path of a color printer for measuring colors (e.g., on printed test sheets, banner / separation pages, etc.) with or without requiring any manual operations or operator involvement. The automatic color balance control system produces spatial tonal reproduction values for all four of the primary colors by printing patches, measuring colors using the sensor combination and automatically readjusting the spatial tone reproduction curves until a satisfactory level of printed color accuracy and uniformity are obtained. While producing color balanced TRCs, the system will automatically lock the printer output to some predetermined color patch targets. In one particular preferred embodiment, this output is locked to neutral gray when target colors are set to neutral gray inside the digital front end (DFE). After converging to the targets, the control system returns full TRCs for use inside the normal print path.

A method of automatic mapping of image data includes representing image data for an image as luminance values, determining a key value as a function of an average luminance value of the image and of minimum and maximum luminance values of the image, generating offset-adjusted luminance values including applying an offset to each of the luminance values, the offset being a function of the determined key value, and computing a tone reproduction curve for at least a region of the image which includes applying a mapping function to the offset-adjusted luminance values.

A method and system updates individualized calibrated tone-reproduction curves. A plurality of predetermined stored calibrated tone-reproduction curves are used, each predetermined stored calibrated tone-reproduction curve corresponding to a distinct media type and halftone type combination along with a plurality of predetermined relationships between each stored calibrated tone-reproduction curve and a reference media type and reference halftone type combination. A new tone-reproduction curve corresponding to a reference media type and reference halftone type combination calibration operation is generated, and each predetermined stored calibrated tone-reproduction curves based on the newly generated tone-reproduction curve corresponding to the reference media type and reference halftone type combination and the plurality of predetermined relationships between each stored calibrated tone-reproduction curve and the reference media type and reference halftone type combination is updated. The TRCs can be applied upon a page basis. Moreover, generated TRCs can be mapped to existing TRCs to save memory.

The tone reproduction characteristics of a color monitor are determined at high precision by visual recognition. A pattern display means (230) displays a test pattern, comprising circular patterns (50) and a background (60), on the screen of the monitor (100) to be measured. In the background (60), a reference pattern, which is generated by a reference pattern generating means (220), is formed of a black-and-white pattern, and has a prescribed reference luminance, is displayed, and in each circular pattern (50), an even pattern with RGB tone values designated by a tone value designating means (210) is displayed. The tone of the even pattern is varied so as to vary in brightness and color by a tone value varying means (240). When the circular patterns (50) become the same in brightness and color as the background (60), an operator provides a coincidence signal to a coincidence signal input means (250). A characteristics computing means (260) computes curves, indicating the tone reproduction characteristics according to the respective colors of R, G, and B, based on the reference luminance and the corresponding tone values at this point. The circular patterns (50) are positioned at a pitch that is in accordance with the spatial frequency sensitivity of human eyes.

Multiple input patches are received on an output media, which patches are characterized by print density representing a document processing system's response to different input grayscale values over a potential response space. Values associated with the print density of each input grayscale value are measured. Reference Engine Response Curves are determined from the measured print density values and input gray scale values. A variance data representative of a difference between each measured print density value and a respective reference Engine Response Curve is determined. The variance data is transformed into individual components. Based at least on one selected individual component, a set of calibration compensating Tone Reproduction Curves is determined. The determined calibration compensating Tone Reproduction Curves are applied to input grayscale values.

The present invention relates to a processing device and a method of providing privacy for a display device comprising a display panel arranged to display a first image signal (405), the display panel having an off-axis tonal reproduction curve that is different from the on-axis tonal reproduction curve of the display panel, and the display panel comprising a group of adjacent subpixels, wherein subpixels of the group of adjacent subpixels contribute at least a common primary color component, and wherein the group of adjacent subpixels associated with at least one pixel; the method comprising modulating control signals of individual subpixels of the group of adjacent subpixels, using a second image signal (425), the control signals arranged to generate tonal values for at least two of the individual subpixels of the group of adjacent subpixels that are at least in part decorrelated from the first image signal when viewed off-axis, and to generate tonal values for the group of adjacent subpixels that on average correspond to the first image signal when viewed on-axis.

A method of adjusting a TRC of an image is provided. The method involves receiving an image at an input resolution, resampling the image to a processing resolution if the imput resolution and the processing resolution are not same, processing the image using rank-ordered error diffusion, and resampling the processed image to a desired output resolution for the image if the processing resolution and the output resolution are not same.

A Gamut Enhance Module (GME) is disclosed for applying 3 independent Tone Reproduction Curves (TRC) to each of the color components of an input image. The implementation is done via three independent and fully programmable 1D lookup tables. The input to the Gamut Enhance Module is the output DSS from a Scaling Module (SCL), representing a scaled and de-screened version of the source image. The output is a gamut-mapped signal GME. The GME unit includes special logic to neutralize (set to gray) or preserve input colors.

A system for compensating for a calibration drift in an image output device includes a user input means for specifying an output medium. An image output device controller converts original image data to final image data used by the image output device. The image output device produces a calibration image, as a function of an output medium, for a plurality of halftone screens capable of being produced by the image output device. A processor communicates with the controller. The processor calculates a plurality of candidate tone reproduction curve sets for the specified output medium. Each of the sets corresponds to one of the plurality of halftone screens. The candidate tone reproduction curve sets are accepted for compensating for a calibration drift in the image output device.

A color correction device for correcting colors in a color image comprises:coordinates for registering points in a first color space of at least one standard point, the first color space having axes for specifying colors;a second set of coordinates for registering points in a second color space of at least one standard point, the second color space having coordinates that include at least one coordinate for specifying color hue;a translator to convert image data of at least one point in the first color space to coordinates in the second color space;a modifier for modifying at least hue within image data in the second color space to form corrected image data in the second color space; anda translator for transferring corrected image data in the second color space to corrected image data in the first color space.The color correction device may include a means for creating a tone reproduction curve based on conceptually moving one or other limit of a range of image color values in order to provide a tone reproduction curve with improved rendering of the color correction.

The method and system for printer color calibration use a combination of a full-width array (FWA) or similar page-scanning mechanism in conjunction with a spectrophotometer color measurement system in the output path of a color printer for measuring colors with or without requiring any manual operations or operator involvement. The automatic color balance control system produces spatial tonal reproduction values for the primary colors by printing patches, measuring colors using the sensor combination and automatically readjusting the spatial tone reproduction curves until a satisfactory level of printed color accuracy and uniformity are obtained.

Color measurements are generated from transform-based device profiles for use in a measurement-based color management system. The color measurements is generated by providing device-dependent color samples to a transform-based color management module and converting them to the profile connection space with the device's transform-based profile. Color measurements are then generated from the transform-based color management module by applying an identity profile in place of a destination device profile. In addition, measurement data can be extracted directly from either the tone reproduction curve / matrix or n-dimensional lookup table transforms contained within a transform-based device profile.

A method of adjusting a TRC of an image is provided. The method involves receiving an image at an input resolution, resampling the image to a processing resolution if the imput resolution and the processing resolution are not same, processing the image using rank-ordered error diffusion, and resampling the processed image to a desired output resolution for the image if the processing resolution and the output resolution are not same.

A method permitting an end user to recalibrate a color reproduction device. The color reproduction device includes a device for converting the native color values of the scanner into a device independent color space, a test target, and the desired values of each patch of the test target. The method includes printing the test target and scanning it with a scanner that forms a part of the color reproduction device. The device compares the desired values with the values obtained from scanning the printed test target to obtain a set of adjustment values to compensate for drift in the output of the color reproduction device. The compensation emphasizes restoration of the overall gray balance of the color reproduction device and can be implemented by modifying the tone reproduction curves or the halftone process used in the color reproduction device.

A xerographic apparatus, a printer, a printer server, and the like processes wavelet domain image data and includes means for receiving the wavelet domain image data representative of an input digital image. The wavelet domain image data may be formatted as a JPEG 2000 compressed file or other wavelet domain file including N levels of wavelet decompositions. An M-level extractor extracts an Mth level wavelet decomposition from the wavelet domain image data where M is <N. The extracted Mth level wavelet decomposition is a low resolution representation of the input digital image. An image enhancement system receives the extracted Mth level wavelet decomposition and derives an enhancement process such as a tone reproduction curve, a sharpness filter, and the like from the extracted Mth level wavelet decomposition. The enhancement process is used to enhance a higher resolution representation of the digital input image.

Watermark information indicative of content of music piece performance data to be reproduced in synchronism with a first audio signal is embedded into the first audio signal, and the resultant signal is acquired as a second audio signal. In parallel to the above-mentioned processing, the watermark information is decoded from the second audio signal, the content of music piece performance data to be reproduced is identified on the basis of the decoded watermark information, and then a tone signal based on the music piece performance data is reproduced in accordance with the identified content.