Abstract: A component of a color printing system, such as lookup tables for converting requested marking-agent coverages to corresponding half-tone screen sizes, is calibrated. The calibration can be effected off an arbitrary image and involves making reflectance spectrum measures of the printed image at multiple locations. Expected reflectance measures for each measurement location are computed based on the requested coverage value for each of the marking agents printed there. The computed measures may be dependent on a parameter. A value of the parameter is determined that minimizes the aggregate differences between the sensed and expected reflectance-spectrum measures, and this value is then used in calibrating the component.

Abstract: A method for compressing a plurality of coordinates includes obtaining a plurality of approximately-zero polynomials of dimension dim for a plurality of coordinate parameters. The method further includes selecting dim+1 non-approximately-zero polynomials, and providing a compressed data set that includes the approximately-zero polynomials, the dim+1 non-approximately-zero polynomials, and evaluations of the selected dim+1 non-approximately-zero polynomials based on the coordinates.

Abstract: Modification of a digital image includes determining a likelihood of a pixel belonging to a memory color region (110). The memory color region has a preferred color. The modification further includes shifting original color of the pixel toward the preferred color (120). The original color is shifted by an amount that is a function of the likelihood and that is generally less than the difference between the original and preferred colors.

Abstract: A method for compressing a plurality of coordinates includes obtaining a plurality of approximately-zero polynomials of dimension dim for a plurality of coordinate parameters. The method further includes selecting dim+1 non-approximately-zero polynomials, and providing a compressed data set that includes the approximately-zero polynomials, the dim+1 non-approximately-zero polynomials, and evaluations of the selected dim+1 non-approximately-zero polynomials based on the coordinates.

Abstract: An apparatus and method detect defects in a captured image of output from a printing device. The captured image is filtered using a source image for the output, wherein specific defects of interest are detected using the filtered image.

Abstract: A method includes obtaining, by executing a module stored on a non-transitory computer-readable storage device, approximately-zero polynomials for each of multiple classes. The method further includes evaluating the approximately-zero polynomials for each class on a plurality of points to compute distances from each point to each of the classes. The method also includes scaling the approximately-zero polynomials based on the distances and classifying the points based on the scaled approximately-zero polynomials.

Abstract: A malfunction diagnosis system of a printer is provided. A printer controller receives malfunction-related input by the user from an input device, which user input specifies a print defect perceptible to the user. It generates image data representing a test print job in response to the user input specifying the perceptible print defect, and forwards the test print job image data to the printing unit to produce a corresponding test printout. Measurement data output from a sensing device as measured on the test printout is received and analyzed, and information indicative of a cause for the print defect based on the analyzed measurement data output from the sensing device is output.

Abstract: Methods, machines, and computer-readable media for processing an input image with a bi-selective filter in a transform domain are described. In one aspect, a forward transform of an input image is computed. A bi-selective filter smoothes image regions with low magnitude coefficients and sharpens image regions with high magnitude coefficients. An output image is generated from the filtered forward transform.

Abstract: A method, diagnostic tool and system are provided for evaluating printing defects. A captured image of a printed sheet is received and a profile generated of the printed sheet, this profile being representative of tonal variations in the printed sheet. The profile is analyzed in a plurality of different scales and an assessment made of the significance of one or more features of a printing defect throughout the plurality of different scales. From the assessed significance of the one or more features, an evaluation is carried out, in each of the plurality of different scales, of the severity of the printing defect.

Abstract: In at least some examples, a system comprises a processor and a memory coupled to the processor. The memory stores an image defect visibility predictor that, when executed by the processor, compares an original image with a defect image and outputs a predicted defect visibility image (PDVI) that accounts for defect masking by the original image.

Abstract: Noise level estimation includes examining color correlation in a digital image.

Abstract: An apparatus and method detect defects in a captured image of output from a printing device. The captured image is filtered using a source image for the output, wherein specific defects of interest are detected using the filtered image.

Abstract: A component of a color printing system, such as lookup tables for converting requested marking-agent coverages to corresponding half-tone screen sizes, is calibrated. The calibration can be effected off an arbitrary image and involves making reflectance spectrum measures of the printed image at multiple locations. Expected reflectance measures for each measurement location are computed based on the requested coverage value for each of the marking agents printed there. The computed measures may be dependent on a parameter. A value of the parameter is determined that minimizes the aggregate differences between the sensed and expected reflectance-spectrum measures, and this value is then used in calibrating the component.

Abstract: A method and apparatus are provided for evaluating the severity in a printed image of a repeating band print artifact. After electronically capturing the printed image, each of a plurality of patches taken from captured image is analysed to produce an artifact severity measure for the patch; an overall artifact severity value is then determined for the printed image from the patch severity measures. The analysis of each patch involves producing a spatial intensity profile across the patch substantially at right angles to an expected direction of extent of any repeating band print artifact present; a Fourier-related transform is then applied to the spatial intensity profile and the patch artifact severity measure generated by summing the resultant spatial frequency coefficients in a limited range about a frequency of interest.

Abstract: Method and system embodiments of the present invention are directed to automated identification of regions within digitally-encoded images that correspond to objects and features of scenes captured in the digitally-encoded images, a process referred to as ‘perceptual segmentation’ of an image. Regions or segments within an image are first identified by any of various region-identifying or segmentation methods. For each region or segment, features of pixels within the region or segment are employed to compute one or more segment features. The segment features are used, in turn, to identify the region or segment as belonging to a particular type of region or segment, and the region is then accordingly labeled or tagged as a region or segment of the determined type.

Abstract: A method and apparatus are provided for evaluating the severity in a printed image of a repeating band print artifact. After electronically capturing the printed image, each of a plurality of patches taken from captured image is analysed to produce an artifact severity measure for the patch; an overall artifact severity value is then determined for the printed image from the patch severity measures. The analysis of each patch involves producing a spatial intensity profile across the patch substantially at right angles to an expected direction of extent of any repeating band print artifact present; a Fourier-related transform is then applied to the spatial intensity profile and the patch artifact severity measure generated by summing the resultant spatial frequency coefficients in a limited range about a frequency of interest.

Abstract: Systems and methods of face and skin sensitive image enhancement are disclosed. In one aspect, a face map that includes for each pixel of an input image a respective face probability value indicating a degree to which the pixel corresponds to a human face is calculated. A skin map that includes for each pixel of the input image a respective skin probability value indicating a degree to which the pixel corresponds to human skin is ascertained. The input image is enhanced with an enhancement level that varies pixel-by-pixel in accordance with the respective face probability values and the respective skin probability values. In another aspect, a facial content measurement value indicating a degree to which an input image contains human face content is ascertained. A tone-correction process is tuned in accordance with the facial content measurement value. The input image is enhanced in accordance with the tuned tone-correction process.

Abstract: In a method of processing an image containing undesirable pixels, a coarse identification of a location of the undesirable pixels is received. The coarse identification includes identification of at least one undesirable pixel and at least one desirable pixel in the image. An area in the image to be analyzed for undesirable pixel values is automatically determined according to the coarse identification received. In addition, in the area determined to be analyzed, the pixels are automatically classified as one of undesirable and desirable and the classifications of the pixels are stored.

Abstract: Modification of a digital image includes determining a likelihood of a pixel belonging to a memory color region (110). The memory color region has a preferred color. The modification further includes shifting original color of the pixel toward the preferred color (120). The original color is shifted by an amount that is a function of the likelihood and that is generally less than the difference between the original and preferred colors.

Abstract: In a method of automatically replacing undesirable pixels in an image, a local neighborhood of pixels is identified around an undesirable pixel. In addition, secondary neighborhoods of pixels are identified and feature values of the pixels contained in the local neighborhood and each of the secondary neighborhoods are calculated. The secondary neighborhoods having feature values within a predetermined range of the local neighborhood feature value are classified as candidates for pixel value replacement. Moreover, a replacement pixel value from at least one of the secondary neighborhoods classified as a candidate for pixel value replacement is determined and the undesirable pixel value is replaced with the replacement pixel value.