摘要:
A system and method provides the necessary image information to enable tonal correction for independent regions of a compound document. A scanner scans an image and generates image data. A histogram circuit, connected to the scanner, generates histogram data from the image data for a predetermined number of regions corresponding to the image. A windowing circuit, operatively connected to the scanner and in parallel with the histogram circuit, generates a window corresponding to an independent area of the image that requires image enhancement and an association circuit associates corresponding histogram data with the generated window. The associated histogram data and window are used by an image enhancement process to modify the image data to provide a more desirable reproduction of the scanned image.
摘要:
A method and system implements a redistributive characteristic into an error diffusion process. A grey level value representing a pixel is received. A threshold circuit thresholds the received grey level value and generates an error value as a result of the threshold. A portion of the error value is diffused to adjacent pixels on a next scanline. All the error for a single pixel on the next scanline is accumulated. Since this accumulated error has a greater number of bits than can be stored in a buffer, a portion of the accumulated error is truncated and redistributed to a down stream pixel for inclusion in the downstream pixel's error accumulation process. The grey level value has a first resolution which corresponds to an original input resolution. In a high addressabilty environment, the received grey level value is interpolated to subpixel grey level values before thresholding.
摘要:
A method and system implements screening and a high addressability characteristic into an error diffusion process. A grey level value representing a pixel is received. The grey level value has a first resolution which corresponds to an original input resolution. The grey level value is then screened. A threshold circuit thresholds the grey level value and generates an error value as a result of the threshold. A portion of the error value is diffused to adjacent pixels on a next scanline. The screened grey level value can also be interpolated to generate subpixel grey level values which correspond to a second resolution. The second resolution is higher than the first resolution and corresponds to the high addressability characteristic. The threshold circuit would then threshold the grey level value and generate an error value having a resolution corresponding to the first resolution.
摘要:
A system and method classify a pixel of image data as one of a plurality of image types. A first image characteristic value for the pixel, a second image characteristic value for the pixel, a third image characteristic value for the pixel, and a fourth image characteristic for the pixel is determined. Some of these determinations may be resolution dependent. The values from these determination are utilized in assigning an image type classification to the pixel. Moreover, if at least one of the image characteristic values is greater than a predetermined threshold value the pixel is classified as a halftone peak value. The system includes a plurality of microclassifiers for determining a distinct image characteristic value of the pixel; a plurality of macroreduction circuits connected to the plurality of microclassifiers for performing further higher level operations upon the distinct image characteristic values of the pixel to produce reduced values; and a classification circuit to classify the pixel as an image type based on the reduced values from the macroreduction circuits. The system also includes a circuit to detect flat peaks without detecting multiple peaks and a rectangular blur filtering system.
摘要:
A process eliminates pattern shifting artifacts in a printed image rendered using a hybrid high addressable error diffusion process by perturbing a threshold/image signal value relationship when a multi-level grey level is binarized. The process utilizes a programmable multi-level grey signal modifying circuit for modifying the multi-level grey signal by a predetermined value according to its grey level. The modified multi-level grey signal is binarized to a binary pixel signal according to a relationship between the modified multi-level grey signal and a threshold value. The process further generates an error corresponding to the relationship and diffuses the error to neighboring pixels. The multi-level grey signal is modified with either random noise multiplied by a grey level dependent coefficient or by a predetermined value from a checkerboard or vertical line pattern. The value from the pattern is dependent upon the grey level and pixel location of the image data.
摘要:
A method and system implements a high addressability characteristic into an error diffusion process. A grey level value representing a pixel is received: The grey level value has a first resolution which corresponds to an original input resolution. The grey level value is interpolated to generate subpixel grey level values which correspond to a second resolution. The second resolution is higher than the first resolution and corresponds to the high addressability characteristic. A threshold circuit thresholds the interpolated grey level value and generates an error value as a result of the threshold. The error value has a resolution corresponding to the first resolution. A portion of the error value is diffused to adjacent pixels on a next scanline.
摘要:
A method and system implements a dynamic error diffusion process. A grey level value representing a pixel is received. An image segmentation circuit determines an image characteristic of the pixel being processed. A threshold circuit thresholds the grey level value (pixel) and generates an error value as a result of the threshold process. A portion of the error value is diffused to adjacent pixels on a next scanline. The distribution of this error value is dynamic in that different sets of weighting coefficients are used based the image characteristic of the processed pixel. One set of coefficients are utilized in processing a pixel having a first image characteristic, and a second set of coefficients are utilized in processing a pixel having a second image characteristic.
摘要:
A process eliminates pattern shifting artifacts in a printed image by perturbing a threshold/image signal value relationship when a multi-level grey level is binarized. The process utilizes a programmable multi-level grey signal modifying circuit for modifying the multi-level grey signal by a predetermined value according to its grey level. The modified multi-level grey signal is binarized to a binary pixel signal according to a relationship between the modified multi-level grey signal and a threshold value. The process further generates an error corresponding to the relationship and diffuses the error to neighboring pixels. The multi-level grey signal is modified with either random noise multiplied by a grey level dependent coefficient or by a predetermined value from a checkerboard or vertical line pattern. The value from the pattern is dependent upon the grey level and pixel location of the image data.
摘要:
A method and system implements a high addressability characteristic into an error diffusion process. A grey level value representing a pixel is received. The grey level value is interpolated to generate subpixel grey level values which correspond to a second resolution. A threshold circuit thresholds the interpolated grey level value. In parallel to the interpolation circuit and threshold circuit is an error circuit which generates a plurality of possible error values. One of the plurality of possible error values is selected based on the number of subpixels exceeding a threshold value. A portion of the selected error value is then diffused to adjacent pixels on a next scanline.
摘要:
A method and system implements a dynamic error diffusion process. A grey level value representing a pixel is received. An image segmentation circuit determines an image characteristic of the pixel being processed. A threshold circuit thresholds the grey level value (pixel) and generates an error value as a result of the threshold process. A portion of the error value is diffused to adjacent pixels on a next scanline. The distribution of this error value is dynamic in that different sets of weighting coefficients are used based the image characteristic of the processed pixel. One set of coefficients are utilized in processing a pixel having a first image characteristic, and a second set of coefficients are utilized in processing a pixel having a second image characteristic.