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HW4, EECS 203A, Computer Problem (a).

By Nasser Abbasi.

Problem.. 1

Conclusion. 1

Solution. 1

Cat results. 1

Original image. 1

Laplace image before and after sharpeing. 2

Triangle results. 4

Original image. 4

Laplace image before and after sharpeing. 4

Source code. 5

Problem

Apply laplacian to image, scale, subtract from original image and display sharpened image.

Conclusion

Sharpened images using subtracting of Laplacian image from original are shown. Both images show the image sharper than original image.

Solution

Cat results

Original image

For the cat, this is the original image (480x640) gray level scale, 8 bits per pixel.

Laplace image before and after sharpeing

Sharp image

Triangle results

Original image

Laplace image before and after sharpeing

Sharp image

Source code

function EECS_203A_HW4_computer_prob_a

%

% Solve HW4, EECS 203A, computer problem a.

% Apply Laplace method of sharpeing.

% Filter image with laplace, then subtract from

% original image and scale.

%

% by Nasser Abbasi

% EECS 203A, UCI, Fall 2004.

%

A=[1 1 1; 1 -8 1; 1 1 1]; % laplace filter

nRow=480; % rows

nCol=640; % columns

fileName='triangle.raw';

fid=fopen(fileName,'r');

f=fread(fid,[nCol,nRow],'uint8');

fclose(fid);

f=f';

figure;

imagesc(f,[0 255]);

colormap gray;

colorbar;

title(sprintf('Original raster file %s',fileName));

% I could use the following matlab function called

% filter2 to do the job, but instruction said to

% use our code so I can have the new image smaller

%

% Y1=filter2(A,f);

% figure;

% imagesc(Y1,[0 255]);

% colormap gray;

% colorbar;

% title(sprintf('laplace filtering using matlab code'));

%

nRow2=nRow-2;

nCol2=nCol-2;

Y2=zeros(nRow2,nCol2);

for(i=1:nRow2)

for(j=1:nCol2)

ii=i+1;

jj=j+1;

Y2(i,j)=f(ii-1,jj-1)*A(1,1) + f(ii-1,jj)*A(1,2) + f(ii-1,jj+1)*A(1,3) ...

+f(ii,jj-1)*A(2,1) + f(ii,jj)*A(2,2) + f(ii,jj+1)*A(2,3) ...

+f(ii+1,jj-1)*A(3,1) + f(ii+1,jj)*A(3,2) + f(ii+1,jj+1)*A(3,3);

end

end

figure;

imagesc(Y2,[0 255]);

colormap gray;

colorbar;

title(sprintf('result of applying laplace filter, before scaling'));

s = min(min(Y2));

s = abs(s);

Y2 = Y2+s;

m = max(max(Y2));

delta = m/255;

Y2 = 1/delta .* Y2;

Y2 = round(Y2);

figure;

imagesc(Y2);

colormap gray;

colorbar;

title(sprintf('result of applying laplace filter after scaling'));

%scale the sharp image

f(2:end-1,2:end-1) = f(2:end-1,2:end-1) - Y2;

s = min(min(f));

s = abs(s);

f = f+s;

m = max(max(f));

delta = m/255;

f = 1/delta .* f;

f = round(f);

figure;

imagesc(f);

colormap gray;

colorbar;

title(sprintf('result of sharpining'));

fileName='triangle_scaled_laplace.raw';

fid=fopen(fileName,'wb');

count=fwrite(fid,Y2','uint8');

fclose(fid);

fprintf('written %d elements to file %s\n',count,fileName);

fileName='triangle_sharp.raw';

fid=fopen(fileName,'wb');

count=fwrite(fid,f','uint8');

fclose(fid);

fprintf('written %d elements to file %s\n',count,fileName);

end