METHOD AND APPARATUS FOR INDENTIFYING AND FIXING HORIZONTAL AND VERTICAL LINES IN DIGITIZED IMAGES

Apparatuses and methods are provided for locating and straightening horizontal and vertical lines in digitized documents by first identifying horizontal or vertical elements, each of which may represent part of a longer line, according to several adjustable criteria. This approach confines use of precise, computationally intensive line-fixing routines to image regions likely to contain a line. In one aspect, the invention performs pixel-by-pixel scanning only in those regions likely to contain a line segment. Given a threshold number of pixels defining the smallest possible line segment, the invention begins with an initial pixel and tests the pixel linearly displaced therefrom by a distance equal to the threshold. If the displaced pixel is uncolored, a consecutive threshold-length run of colored pixels cannot exist between the initial and displaced pixels, so all of these pixels are considered evaluated and the displaced pixel becomes a new initial pixel. If both the initial and displaced pixels are colored, the invention examines a series of pixels progressively closer to the initial pixel; if any of these is found to be uncolored, it is defined as a new initial pixel, once again skipping over intervening pixels.