Programmable apparatus for determining document background level
First Claim
1. In an image processing system suitable for processing an image represented by a plurality of video signals, said video signals representing both the content regions of the image and the background regions of the image, an apparatus for determining the background level of the image comprising:
- sampling means for sampling a selected portion of the video signals in the image;
means, coupled to said sampling means, for identifying sampled video signals which are non-representative of the background regions of the image, said identifying means eliminating the non-representative video signals from the selected portion of the video signals; and
means, coupled to said identifying means, for calculating a background level as a function of the level of the non-eliminated sampled video signals.
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Abstract
An apparatus for efficiently determining the background level of an image, based upon a sampling of the image, during processing of the image signals and without the need for a prior scan operation. The apparatus includes programmable sampling counters, to indicate when image signals for background determination are present on the video path, and an image signal verification device for excluding signals which are not representative of background regions of the image. The background determination apparatus also includes arithmetic circuitry for calculating a background level based upon the sampled image signals and for determining additional threshold levels based upon the background level.
56 Citations
29 Claims
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1. In an image processing system suitable for processing an image represented by a plurality of video signals, said video signals representing both the content regions of the image and the background regions of the image, an apparatus for determining the background level of the image comprising:
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sampling means for sampling a selected portion of the video signals in the image; means, coupled to said sampling means, for identifying sampled video signals which are non-representative of the background regions of the image, said identifying means eliminating the non-representative video signals from the selected portion of the video signals; and means, coupled to said identifying means, for calculating a background level as a function of the level of the non-eliminated sampled video signals. - View Dependent Claims (2, 3)
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4. In an image processing system suitable for processing an image represented by a plurality of video signals, said video signals representing both the content regions of the image and the background regions of the image, an apparatus for determining the background level of the image comprising:
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sampling means for sampling a selected portion of the video signals in the image; means, coupled to said sampling means, for identifying sampled video signals which are non-representative of the background regions of the image, including memory means for receiving and storing a background threshold, means, in communication with said memory means, for comparing the level of the sampled video signal against the stored background threshold and providing a signal indicating when the sampled video signal is below the background threshold, means, responsive to the signal produced by said comparing means, for eliminating the non-representative video signal, said eliminating means eliminating the non-representative video signals from the selected portion of the video signals; means, coupled to said identifying means, for calculating a background level as a function of the level of the remaining sampled video signals; and means for substituting an alternate video signal for each non-representative signal eliminated. - View Dependent Claims (5)
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6. In an image processing system suitable for processing an image represented by a plurality of video signals, said video signals representing both the content regions of the image and the background regions of the image, an apparatus for determining the background level of the image comprising:
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sampling means for sampling a selected portion of the video signals in the image; means, coupled to said sampling means, for identifying sampled video signals which are non-representative of the background regions of the image, said identifying means eliminating the non-representative video signals from the selected portion of the video signals; means, coupled to said identifying means, for calculating a first background level as a function of the level of the non-eliminated sampled video signals; and means for computing a second background level for use by the image processing system, with the second background level being a fractional portion of the first background level. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. An apparatus for determining the magnitude of the background in an image represented by a plurality of video signals, wherein said video signals represent both the content and the background regions of the image, including:
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windowing means for identifying a selected portion of the video signals in the image; means, coupled to said windowing means, for identifying those selected video signals which represent the content regions, said identifying means eliminating the content region video signals, thereby leaving video signals representative of the background region; and arithmetic means, coupled to said qualification means, for calculating a background magnitude as a function of the magnitude of the background region video signals.
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14. An apparatus for determining the magnitude of the background in an image represented by a plurality of video signals, wherein said video signals represent both the content and the background regions of the image, including:
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windowing means for identifying a selected portion of the video signals in the image, wherein said windowing means includes means for storing coordinates, of a window region, and means responsive to the stored window coordinates for generating a window signal associated with the video signal, with the level of the window signal being indicative of whether the video signal is within the window region; means, coupled to said windowing means, for eliminating the selected video signals which are representative of the content regions, thereby leaving video signals representative of the background region; and arithmetic means, coupled to said qualification means, for calculating a background magnitude as a function of the magnitude of the background region video signals. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. The method of determining the level of the background region of an image represented by a plurality of video signals, during the processing of the video signals, comprising the steps of:
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receiving the video signals as a stream of sequential signals; sampling a selected portion of the video signals received; eliminating sampled video signals that are non-representative of the level of the background region; and calculating a background level as a function of the non-eliminated sampled video signals. - View Dependent Claims (23)
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24. The method of determining the level of the background region of an image represented by a plurality of video signals, during the processing of the video signals, comprising the steps of:
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receiving the video signals as a stream of sequential signals; sampling a selected portion of the video signals received, said sampling step including, identifying the boundaries of a window encompassing the selected portion of the image by initializing at least one slow-scan counter with a coordinate value representing a boundary of the window, initializing at least one fast-scan counter with a coordinate value representing a boundary of the window, and using the coordinate values stored in said fast-scan and slow-scan counters to represent the window boundaries, and generating a sample signal indicating when a received video signal is within said window; eliminating sampled video signals that are non-representative of the level of the background region; and calculating a background level as a function of the non-eliminated sampled video signals. - View Dependent Claims (25)
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26. The method of determining the level of the background region of an image represented by a plurality of video signals, during the processing of the video signals, comprising the steps of:
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receiving the video signals as a stream of sequential signals; sampling a selected portion of the video signals received; eliminating sampled video signals that are non-representative of the level of the background region, said eliminating step including storing a background threshold value, comparing the magnitude of the sampled video signal against the stored background threshold value, and bypassing the sampled video signal at any time the magnitude of the sampled video signal is less than the stored background threshold value; calculating a background level as a function of the non-eliminated sampled video signals. - View Dependent Claims (27)
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28. The method of determining the level of the background region of an image represented by a plurality of video signals, during the processing of the video signals, comprising the steps of:
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receiving the video signals as a stream of sequential signals; sampling a selected portion of the video signals received; eliminating sampled video signals that are non-representative of the level of the background region; and calculating a background level as a function of the non-eliminated sampled video signals, including calculating a weighted running average of the magnitudes of the non-eliminated sampled video signals. - View Dependent Claims (29)
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Specification