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POHow to detect and remove guide lines from a scanned image/document efficiently?
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  1. POHow to detect and remove guide lines from a scanned image/document efficiently?
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    copied!<p>For my project i am writing an image pre processing library for scanned documents. As of now I am stuck with line removal feature. </p> <p>Problem Description: A sample scanned form:</p> <pre><code>Name* : ______________________________ Age* : ______________________________ Email-ID: |_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_| </code></pre> <p><b>Note:</b> Following are the further conditions:</p> <ul> <li>The scanned document may contain many more vertical and horizontal guiding lines. </li> <li>Thickness of the lines may exceed 1px</li> <li>The document itself is not printed properly and might have noise in the form of ink bloating or uneven thickness</li> <li>The document might have colored background or lines</li> </ul> <p>Now what I am trying to do is to detect these lines and remove them. And while doing so the hand written content should not be lost. </p> <p>Solution so for: The current solution is implemented in Java.</p> <p>Detected these lines by using a combination of canny/sobel edge detectors and a threshold filter(to make image bitonal). From the previous action I get a black and white array of pixels. Traverse the array and check whether lumanicity of that pixel falls below a specified bin value. And if I found 30 (minimum line length in pixels) such pixels, I remove them. I repeat the same for vertical lines but considering the fact there will be cuts due to horizontal line removal.</p> <p>Although the solution seems to work. But there are problems like,</p> <ul> <li>Removal of overlapping characters</li> <li>If characters in the image are not properly spaced then it is also considered as a line.</li> <li>The output image from edge detection is in black and white.</li> <li>A bit slow. Normally takes around 40 seconds for image of 2480*3508.</li> </ul> <p>Kindly guide how to do it properly and efficiently. And if there is an opensource library then please direct.</p> <p>Thanks</p>
 

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