hw4_001

# hw4_001 - right pixels with the following weights(7 16 3 16...

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ECE178 HW #4 DUE: Friday, October 23, 2009 (by 5PM in the HW box) Questions 0 to 4 are from the 3 rd chapter of Digital Image Processing book by Gonzalez and Woods ( 3 rd Edition). Q0 . Review textbook problems 3.16, 3.19, 3.24, 3.25, 3.28. No need to turn in solutions to these problems. Q1 . problem 3.13 Q2 . problem 3.14 Q3 . problem 3.17 Q4 . problem 3.23 Q4 . Write a MATLAB program to reduce the eﬀect of 1-bit quantization using “Floyd-Steinberg Dithering Algorithm”. Compare your results with uniform quantization without dithering. Comment on the diﬀerences. Use the “lena.gif” (See class website www.ece.ucsb.edu/ ~ manj/ ece178 ) to test your program. In the “Floyd-Steinberg Dithering Algorithm” quantization error introduced at each pixel is spread over the neighboring pixels as follows: Quantization error observed at pixel ( i,j ) is diﬀused to the right, lower left, below and lower

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Unformatted text preview: right pixels with the following weights (7 / 16 , 3 / 16 , 5 / 16 , 1 / 16). Here, note that the weights sum up to 1. Pseudo-code for the algorithm: 1 for i = 1 to height for j = 1 to width I2(i,j) = Q(I(i,j)); error = I(x,y)-I2(x,y); I(i,j+1) += 7 * error/16; I(i+1,j-1) += 3 * error/16; I(i+1,j) += 5 * error/16; I(i+1,j+1) += error/16; end for end for Here Q ( . ) represents inform quantization operator. In this homework, assuming that I ( i,j ) is uniformly distributed over [0 , 1], Q ( I ( i,j )) can be deﬁned as follows: Q ( I ( i,j )) = ± 1 I ( i,j ) ≥ . 5 else Things to turn in: (a) M-ﬁle (b) Output of uniform quantization (c) Output of “Floyd-Steinberg Dithering Algorithm” (d) Comments on the diﬀerences between results. 2...
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hw4_001 - right pixels with the following weights(7 16 3 16...

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