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I have questions in the ‘Noise region definition’ and ‘Noise generation process’ of the paper “A character degradation model for grayscale ancient document images”.

  1. In Noise region definition, g controls the flatness of the regions. What does it exactly mean? How can we say that a noise region is flatter compared to another noise region?

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Below is the illustration of the ellipse noise region within the document image. The green ellipse shape is defined to be the noise region.

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  1. According to paragraph below, the average value bj of its 8-neighbours (in the initial grayscale image) is used for calculating values of all pixels in the line CiBj.

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Does the average value of bj calculated by averaging the greyscale value of the adjacent pixels in north, northeast, east, south east, south, south west, west and north west?

  1. Does the formula for getting Pk is below.

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Please refer to the paragraph below:

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I just want to assess , if my comprehension in reading the article is right. Thanks.

alyssaeliyah
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    The question is lengthy and detailed. Maybe it's a good idea to consider a bounty for it.This helps your question to get more attention by other users too. – MeiH May 25 '20 at 08:44

1 Answers1

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  1. "Flattening" Refers to the effect of g on flatting the ellipse. If alpha is small b, the minor axis of the ellipse, is almost equal to a, the major axis, which will make the ellipse look like a circle. If g is almost 1 the minor axis will be so small that it will look like a line, very "flat".

  2. Yes i think you are correct. Pixel Connectivity

  3. Yes i think you are correct. Each pixel along the line between ci and bj will be a random sample from a normal distribution. The mean of the distribution is a linear interpolation of the expected gray scale.

Amitay Nachmani
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