147 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.

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.

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 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; and
  • a 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.

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 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.