Digital Image Processing Halftoning Lab Title: Binary Image Rendering using Half
ID: 3749482 • Letter: D
Question
Digital Image Processing
Halftoning Lab
Title: Binary Image Rendering using Halftoning. Halftoning is a technique that uses patterns of black and white dots to simulate a grayscale image. It is useful when an output device can only print or display black or white. The figure below shows 3x3 patterns of black and white dots that you will use to represent blocks of 3x3 pixels in grayscale images. That is, the input will be a grayscale image whose pixels have values from 0 to 255 and the output will be an image that only contains two values, one corresponding to black and the other to white 0 2 4 (Ignore the fact that the dots above are circular. They should really be square.) Your assignment In MATLAB, write the function halftone that takes a grayscale image with values 0-255 as its input (this input should be a matrix, not a filename) and returns a binary (two-valued) image (again a matrix) as its output. The input and output should be of type uint8. Your function should use the 10 dot patterns above to transform the grayscale image to the binary image. You will have to decide on this transformation. Importantly, your input and output images should have the same size (number of pixels). Include the code for this function in your lab report Write a test script that generates a test pattern image consisting of a gray scale "wedge" of size 256x256, whose first row is all 0, the next row is all 1, and so on, with the last row being 255. a) b)Explanation / Answer
a)
Code:
clc;clear all; close all;
%inImage = (imread('image.jpg'));
inImage =uint8([255,255,255,255,255,255,255,243,210,156,121,111,110,111,122,157,209,244,254,255,255,255,255,255,255,255,255,255,255,255,254,243,210,155,122,111,110,111,111,112,122,156,210,243,254,255,255,255,255,255;255,255,255,255,255,255,253,240,194,123,76,62,61,62,77,122,195,239,253,255,255,255,254,255,255,255,255,255,255,255,253,240,193,123,77,62,61,61,61,62,76,122,194,240,254,255,255,255,255,255;255,255,255,255,255,255,253,238,190,111,62,48,47,48,62,112,189,239,254,255,255,255,255,255,255,255,255,255,255,255,253,238,190,112,62,48,46,46,46,48,62,111,190,238,252,254,255,255,255,255;255,255,255,255,255,255,253,238,189,111,62,46,44,47,61,111,189,239,253,255,255,255,255,255,255,255,255,255,255,255,253,238,189,110,61,47,44,44,45,47,61,110,189,238,253,255,255,255,255,255;255,255,255,255,255,255,253,239,189,111,61,47,45,46,61,110,189,238,253,255,255,255,255,255,255,255,255,255,255,255,253,238,189,110,61,46,44,44,45,46,61,110,189,238,253,255,255,255,255,255;255,255,255,255,254,255,253,238,189,111,61,46,44,46,61,110,189,239,253,255,255,255,255,255,255,255,255,255,255,255,253,238,189,110,61,46,45,45,44,46,61,110,189,238,253,255,255,255,255,255;255,255,255,255,255,255,253,238,189,111,61,46,44,46,61,110,189,239,253,255,255,255,255,255,255,255,255,255,255,255,253,238,189,110,61,47,45,44,44,47,61,110,189,238,253,255,255,255,255,255;254,253,253,253,253,253,251,237,188,109,61,47,45,46,61,110,188,236,251,253,253,253,253,253,253,253,253,253,253,253,251,237,188,110,61,46,44,45,45,47,61,110,188,237,252,253,253,253,253,254;243,241,238,239,238,238,236,223,178,105,60,46,44,46,60,105,177,224,236,238,239,238,239,238,238,238,238,238,238,238,236,223,178,105,61,46,45,45,45,47,60,105,178,223,236,238,239,238,240,243;211,195,190,189,188,189,187,178,143,90,56,45,44,45,56,90,144,178,187,189,189,189,189,189,189,189,189,189,189,189,187,178,143,90,56,45,45,44,44,46,56,90,143,177,187,189,189,189,195,210;157,123,113,112,111,112,111,106,91,66,50,46,45,45,50,66,90,107,112,112,112,112,111,112,112,112,112,111,112,112,111,106,91,66,49,45,45,44,44,45,49,65,91,107,112,112,112,113,123,157;133,91,79,78,77,77,77,75,67,55,47,45,44,45,47,55,67,75,77,77,77,77,77,77,77,77,77,77,78,77,77,75,67,55,48,45,45,44,44,44,48,55,67,75,76,77,77,79,92,132;156,123,113,112,112,112,112,107,91,66,50,45,44,45,49,66,91,107,111,112,112,112,112,112,112,112,112,112,112,112,112,107,91,65,49,45,44,45,44,45,49,65,90,107,111,112,112,113,122,157;210,194,189,189,189,189,188,178,144,91,56,45,44,45,56,90,144,177,187,189,189,189,189,189,189,189,189,189,189,189,187,178,144,90,56,46,44,45,44,46,56,90,143,178,188,189,189,190,195,210;244,240,238,238,238,238,236,223,178,105,60,47,45,46,60,105,178,223,237,239,238,238,238,238,238,238,238,239,239,239,236,223,177,105,59,46,45,45,45,46,60,105,178,223,237,238,238,239,241,243;254,254,252,253,253,253,250,237,188,109,61,46,44,47,61,110,188,237,251,253,253,253,253,253,253,253,252,253,253,253,252,237,188,109,61,47,44,44,45,46,61,109,188,236,251,253,253,253,253,254;255,255,255,255,255,255,253,238,189,110,61,46,44,46,61,110,189,238,253,255,255,255,255,254,255,255,255,255,255,255,253,238,188,110,61,46,44,44,44,46,61,110,189,238,253,255,255,255,255,255;255,255,255,255,255,255,253,238,190,111,61,46,44,46,61,110,189,238,253,255,255,255,255,255,255,255,255,255,255,255,253,239,189,110,61,46,44,44,45,47,62,110,189,238,253,255,255,255,255,255;255,255,255,255,255,255,253,238,189,110,61,47,44,46,61,111,189,238,253,255,255,255,255,255,255,255,255,255,255,255,253,239,189,110,61,46,44,45,44,46,61,110,189,238,253,255,255,255,255,255;255,255,255,255,255,255,253,238,189,111,61,47,44,46,61,111,189,238,253,255,255,255,255,255,255,255,255,255,255,255,253,238,189,111,61,46,44,45,44,46,61,110,189,239,253,255,255,255,255,255;255,255,255,255,255,255,253,238,188,110,61,47,45,46,61,110,190,239,253,255,255,255,255,255,255,255,255,255,255,255,253,239,189,111,61,47,44,44,44,46,61,110,189,238,253,255,255,255,255,255;255,255,255,255,255,255,253,238,189,110,61,47,45,47,61,110,189,238,254,255,255,255,255,255,255,255,255,255,255,255,253,239,189,110,61,47,45,44,44,47,61,110,189,238,253,255,255,255,255,255;254,253,252,253,253,253,251,237,187,110,61,46,44,47,61,110,188,237,251,253,253,253,253,253,253,253,253,253,253,253,251,237,187,110,61,46,44,44,44,46,61,110,188,237,251,253,253,253,253,254;243,240,238,238,238,238,236,223,178,105,60,47,44,47,60,106,178,224,236,238,239,238,238,238,238,238,238,238,239,239,236,222,178,105,60,47,44,45,45,46,60,105,178,223,236,238,238,238,240,243;209,195,190,189,189,189,188,178,143,90,56,46,45,45,56,89,144,178,188,188,189,189,189,189,189,189,189,189,189,189,188,178,143,90,56,46,44,45,44,45,56,91,144,177,188,189,189,190,195,210;156,122,112,111,110,110,110,105,90,65,50,45,45,45,49,66,89,105,110,111,111,110,111,111,110,111,111,110,110,110,110,105,90,64,50,46,44,44,45,45,49,65,90,105,110,110,110,111,121,156;123,76,63,61,61,62,61,59,55,49,46,44,44,45,46,49,56,59,61,61,61,62,61,61,61,61,61,61,61,61,61,60,55,49,45,44,44,44,45,44,45,49,55,59,61,62,61,62,76,122;111,63,48,46,46,47,47,46,46,45,44,44,44,44,45,45,45,46,47,46,46,47,46,47,47,46,46,46,47,46,46,46,46,46,44,44,45,44,45,45,44,45,46,46,47,47,46,47,62,111;111,62,46,45,45,44,44,44,44,45,45,45,45,44,45,44,45,45,45,45,44,44,44,45,45,44,44,44,44,44,44,44,44,44,44,45,45,44,44,45,44,45,44,44,44,44,45,47,61,111;111,61,47,45,45,45,44,44,44,44,45,44,44,45,45,45,44,44,44,45,45,45,45,44,45,45,44,45,44,44,44,44,45,44,44,45,44,45,44,45,44,44,44,44,44,44,45,46,61,110;110,61,47,44,44,45,45,44,45,44,44,45,45,45,44,44,44,44,45,44,44,45,45,44,44,45,44,45,44,44,44,45,44,44,45,45,44,44,44,45,45,44,44,45,44,45,45,47,61,110;110,61,46,44,45,44,44,45,45,45,44,44,44,44,45,45,44,44,45,44,45,44,44,45,44,45,44,44,45,44,44,44,44,44,44,45,44,45,44,44,45,44,44,44,44,45,44,47,61,110;110,61,46,45,44,44,44,45,44,44,44,44,44,44,45,44,45,45,44,44,44,44,44,44,45,44,44,44,44,44,44,44,45,44,45,44,44,45,44,45,44,44,44,44,44,44,44,47,61,111;110,61,46,44,44,45,44,44,44,44,45,44,45,45,45,44,44,44,44,44,44,44,44,44,44,44,44,44,44,45,45,45,45,44,44,45,45,44,44,45,45,45,45,44,44,44,44,46,61,111;111,61,46,44,44,44,44,44,45,44,44,45,45,44,44,44,44,44,45,45,45,45,44,44,44,44,45,44,44,45,45,45,45,45,44,44,44,45,45,44,45,44,44,44,44,44,45,46,61,111;111,61,46,45,44,44,45,45,45,45,44,44,44,45,45,44,44,44,44,44,44,44,45,45,44,44,44,44,45,45,44,44,44,45,45,45,45,45,44,45,45,45,45,44,45,45,45,46,61,111;110,61,47,45,44,44,45,44,44,45,44,45,45,44,45,44,45,44,45,45,44,44,44,44,44,44,44,45,45,45,45,45,45,45,44,44,44,44,44,45,44,45,45,44,44,44,44,46,61,110;112,62,47,47,47,46,47,46,46,45,45,45,45,44,45,45,46,46,46,47,47,46,46,46,46,46,46,47,46,46,47,46,45,45,45,44,44,45,44,44,45,45,45,46,47,47,46,47,62,112;122,77,62,62,62,61,61,59,55,49,46,45,44,45,45,49,55,60,61,61,61,61,61,61,61,61,61,62,61,61,61,59,56,49,46,45,44,45,45,45,46,50,56,59,60,61,62,62,76,123;156,121,112,110,110,110,110,105,90,65,49,45,45,45,49,65,90,104,110,110,111,110,111,110,111,111,111,111,110,111,110,105,89,65,49,45,44,45,44,46,49,66,89,105,110,110,111,112,121,156;209,196,189,189,189,189,188,178,143,90,56,45,44,45,56,90,143,179,187,189,189,189,189,189,189,189,189,189,189,189,188,178,144,89,56,45,44,45,45,46,56,90,145,177,187,189,189,190,195,210;244,240,239,238,238,239,237,223,178,106,60,46,45,47,60,106,179,223,236,239,238,238,238,238,238,238,238,238,239,238,236,224,177,106,60,46,45,44,44,47,60,106,177,223,237,238,238,238,240,244;253,253,253,253,253,253,251,236,188,109,61,46,45,48,61,110,187,236,252,253,253,253,253,253,253,253,253,253,253,254,251,236,188,110,60,46,44,44,44,46,61,110,188,236,250,252,253,253,253,254;255,255,255,255,255,255,252,239,189,111,62,46,44,46,61,111,189,239,253,254,255,255,255,255,255,255,255,255,255,255,253,238,188,110,61,47,44,45,45,46,61,111,189,239,253,255,255,255,254,255;254,255,255,255,255,255,253,238,189,111,61,47,45,46,61,110,189,238,253,255,255,255,255,255,255,255,255,255,255,255,253,239,189,110,61,46,44,45,45,47,61,111,189,238,253,255,255,255,255,255;255,255,255,255,254,255,253,238,189,111,61,46,44,47,61,110,189,238,253,255,255,254,255,255,255,255,255,255,255,255,253,238,189,110,61,46,45,45,44,46,61,111,189,239,253,255,255,255,255,255;255,255,255,255,255,255,253,238,189,110,61,46,44,46,61,111,189,238,253,255,255,255,255,255,255,255,255,255,255,255,253,238,189,111,61,46,44,45,45,46,61,111,189,238,253,255,255,255,255,255;255,255,255,255,255,255,253,239,190,111,62,48,46,48,62,111,189,238,253,255,255,255,255,255,255,255,255,255,255,255,254,239,190,112,62,47,46,46,46,48,63,111,189,238,253,255,255,255,255,255;255,255,255,255,255,255,253,240,194,122,76,62,61,62,76,122,194,240,253,255,255,255,255,255,255,255,255,255,255,255,253,240,194,123,76,62,61,61,61,62,76,122,194,240,253,255,255,255,255,255;255,255,255,255,255,255,254,243,210,156,121,111,111,112,122,156,209,243,254,255,255,255,255,255,255,255,255,255,255,255,254,243,210,156,122,112,110,110,111,111,121,156,210,243,254,255,255,255,255,255]);
outImage = halftone(inImage);
subplot(121)
imshow(inImage)
subplot(122)
imshow(outImage)
Function:
function outImage = halftone(inImage)
[m,n] = size(inImage);
% for making image size multiple of 3
mp = ceil(m/3)*3;
np = ceil(n/3)*3;
% inImage = [inImage; zeros()]
Image = 255*ones(mp,np);
Image(1:m,1:n) = inImage;
%% Pattern blocks
s =3; % block size
pattern = zeros(s,s,s*s+1); % Note: pattern numbers are from 1 to 10
pattern(:,:,1) = zeros(3);
pattern(:,:,2) = [0 255 0;0 0 0; 0 0 0];
pattern(:,:,3) = [0 255 0;0 0 0; 0 0 255];
pattern(:,:,4) = [255 255 0;0 0 0; 0 0 255];
pattern(:,:,5) = [255 255 0;0 0 0; 255 0 255];
pattern(:,:,6) = [255 255 255;0 0 0; 255 0 255];
pattern(:,:,7) = [255 255 255;0 0 255; 255 0 255];
pattern(:,:,8) = [255 255 255;0 0 255; 255 255 255];
pattern(:,:,9) = [255 255 255;255 0 255; 255 255 255];
pattern(:,:,10)= [255 255 255;255 255 255; 255 255 255];
%% Processing
upImage = zeros(m,n); % image under processing
% idea Halftonig :
% First divide the grayscale to 's' regions
% then then assign the each region to corresponding block
% example: lower region assgn to first block
% upper region to last block
pnm = zeros(m,n);
for i=1:mp/3
for j=1:np/3
avgInImage = mean(mean(Image((i*3-2):(i*3),(j*3-2):(j*3))));
pn = ceil(avgInImage/(256/(s*s+1))); % pattern number corresponding to pixel
upImage((i*3-2):(i*3),(j*3-2):(j*3)) = pattern(:,:,pn);
end
end
upImage = uint8(upImage);
outImage = upImage(1:m,1:n);
end
b)
clc;
A=zeros(256,256); % initializing matrix A of size 256*256 with zero
% creating the test pattern image of grayscale wedge
for i=1:256
for j=1:256
A(j,i)=i-1;
end
end
imshow(A,[]); % showing the wedge image
title('Grayscale wedge');
c) More Information Needed: Figures.