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US 2002/0158192 A1Published application
Method for compensation for dust for an image scanner with a moving document
AssigneeHewlett-Packard Development Company, L.P.
InventorRobert G. Gann
Life of this patent
Estimating the term…
Abstract
Image data in an image scanner is examined to determine whether lines (light or dark) are present in the image data. By examining whether the lines are present in image data for multiple colors, and whether calibration gains for corresponding photosensors are normal, it can be determined whether the lines are likely caused by a surface defect, on a calibration target, or on a platen, or on an image being scanned.
Claims18
A method, in an image scanner, for detecting a defect, comprising:
- determining whether lines are present in image data for multiple color channels;
- and
- determining whether calibration gains for photosensors corresponding to the lines are normal.
A method for detecting a defect on a calibration target for an image scanner, comprising:
- determining that a gain associated with a particular photosensor, in a particular line-array of photosensors, in a photosensor assembly, exceeds a predetermined gain threshold, the gain having been calibrated using the calibration target;
- determining that an image intensity measurement for the particular photosensor exceeds a predetermined intensity threshold;
- and
- determining that an image intensity measurement for each photosensor, physically corresponding to the particular photosensor, in all line-arrays in the photosensor assembly other then the particular line-array of photosensors, does not exceed the predetermined intensity threshold.
1 more element
A method for detecting a defect in image data, comprising:
- determining that intensity data, from a particular photosensor, in a particular line-array of photosensors, in a photosensor assembly, is less than a predetermined intensity threshold;
- and
- determining that intensity data, for each photosensor, physically corresponding to the particular photosensor, in all line-arrays in the photosensor assembly other then the particular line-array of photosensors, is not less than the predetermined intensity threshold.
A method, in an image scanner, for detecting a defect, comprising:
- determining whether a line is present in image data for a first color channel;
- and determining whether the line is not present in image data for a second color channel, where the spectral bandwidths of light received by photosensors for the first and second color channels are identical or nearly identical.
A scanner, comprising:
- a first line-array of photosensors;
- a second line-array of photosensors;
- a processor;
- and
- the processor determining that a defect exists when lines are present in image data from only one of the first and second line-arrays of photosensors and when calibration gains, associated with photosensors corresponding to the lines, are normal.
2 more elements
A scanner, comprising:
- a calibration target;
- a photosensor assembly comprising a plurality of line-arrays of photosensors;
- a processor;
- a particular photosensor, in a particular line-array of photosensors, in the photosensor assembly, having an associated gain that exceeds a predetermined gain threshold, the gain having been calibrated using the calibration target;
- the particular photosensor having an associated image intensity measurement that exceeds a predetermined intensity threshold;
- and
- the processor determining that a defect exists when an image intensity measurement for each photosensor physically corresponding to the particular photosensor, in all line-arrays in the photosensor assembly other then the particular line-array of photosensors, does not exceed the predetermined intensity threshold.
4 more elements
A scanner, comprising:
- a calibration target;
- a photosensor assembly comprising a plurality of line-arrays of photosensors;
- a processor;
- a particular photosensor, in a particular line-array of photosensors, in a photosensor assembly, having an associated image intensity measurement that is less than a predetermined intensity threshold;
- and
- the processor determining that a defect exists when an intensity output, for each photosensor physically corresponding to the particular photosensor, in all line-arrays in the photosensor assembly other then the particular line-array of photosensors, is not less than the predetermined intensity threshold.
3 more elements
A scanner, comprising:
- a first line-array of photosensors;
- a second line-array of photosensors, where the first and second line-arrays of photosensors receive spectral bandwidths of light that are substantially the same;
- a processor;
- and
- the processor determining that a defect exists when a line is present in image data for only one of the first and second line-arrays of photosensors.
2 more elements
Dependencies are inferred from the claim text.