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US5467410A Identification of a blank page in an image processing system 失效
识别图像处理系统中的空白页

Identification of a blank page in an image processing system
摘要:
The present invention provides a robust technique for quickly determining whether a binary input image originated as a blank page. The technique provides reliable sensing in the presence of various image and scanner noise in the input image. In broad terms, the invention contemplates reducing the input image with a low threshold, labeling (by size) connected components (8-connected or 4-connected), and performing a threshold analysis. The threshold analysis typically entails size and numerical thresholds, taking into account the characteristic dimensions of expected types of noise. In specific embodiments, the reduction is performed as a textured reduction wherein the image is divided into tiles, and a single row of pixels in each tile is checked to see whether there are any ON pixels. If there are, the corresponding pixel in the reduced image is ON, otherwise it is OFF. Optional morphological operations are performed to remove expected sources of noise (e.g., pepper noise and thin horizontal lines). The invention further recognizes that a faxed page may contain vertical streaks that are not part of the original paper document. Thus, the threshold analysis typically allows a certain number of such streaks to be present without concluding that the page is not blank. A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.
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