Polytechnic University, Dept. Electrical and Computer Engineering

EE3414 Multimedia Communication System I

Spring 2006, Yao Wang

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Homework 7 (Image Processing: noise-removal and sharpening)

Reading assignment:

·  Gonzalez and Woods, Digital image processing, 2nd edition, Prentice Hall, 2002. Sec. 4.3, 4.4, 5.1 – 5.3

(copies provided)

1.  Assume the image in Fig. 1(a) is the original, and that in Fig. 1(b) is with noise. For the image block in Fig.1(b), determine the image obtained after a) an averaging filter with 3x3 pixel window, b) a median filter with 3x3 pixel window. In both cases, you only need to determine the filtered values for pixels inside the one-pixel-width boundary (i.e. you don’t need to perform filtering for pixels in the top row, bottom row, leftist and rightist columns). Also, you should round the filtered value to integer values. By comparing your results with the original image, comment on the capability of each filter in removing noise while preserving edges.

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Fig. 1(a)

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Fig. 1(b)

2.  For the image given in Fig. 1(a), apply the following filter

Determine the filtered image. Comment on the function of the filter, both based on the filter function itself as well as the filtered image.

3.  For the image given in Fig. 1(a), apply the following filter

Determine the filtered image. Comment on the function of the filter, both based on the filter function itself as well as the filtered image.