| 摘要 |
A line image or a line signature is optically scanned to generate digital signals for storage in an image matrix. These digital signals represent black and white cells defining the line signature or line image and are initially processed by tracing the image boundary. During the tracing a "thinning" or "peeling off" operation is performed that evaluates black cells in the image matrix for conversion into white cell digital signals. This thinning or peeling off process, also identified as data compression, continues until the line signature or line image is composed of a single cell thickness. The final phase of the data compression operation includes another boundary tracing of the one cell thick image, and connecting a sequence of boundary points defining each black cell to form a string of vectors which represent the signature. The resulting vector catalog comprises a composition of data including a vector starting point and vector directions which are encoded and stored for future retrieval. When a stored line signature or line image is to be retrieved for display, the encoded vector data is recalled from storage to generate on a cathode ray tube the original vector data. This operation is known as data decompression and produces on the cathode ray tube a synthesis of the original line image or line signature. The compression and decompression operations, except thinning or peeling off, are also applicable to textured images or images having grayscale and thickness. Such textured images are first subdivided into binary images, each representing one bit of the grayscale, then the vector boundary encoding process is completed without thinning. The encoded vectors are stored for subsequent retrieval and display.
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