Prerequisite: Read EdgeDetection fundamentals
For Xdirection,
For Ydirection,
By substituting, Equations in Fig.B and Fig.C in Fig.A, we
obtain the following equation
The equation represented in terms of Mask:
0

1

0

1

4

1

0

1

0

When the diagonals also considered then the equation
becomes,
The Mask representation of the above equation,
1

1

1

1

8

1

1

1

1

Now let’s discuss further how image
sharpening is done using Laplacian.
Equation:
Where f(x,y) is the input image
g(x,y) is the sharpened image and
c= 1 for the above mentioned
filter masks.(fig.D and fig.E)
MATLAB CODE:
%Input Image
A=imread('coins.png');
figure,imshow(A);
%Preallocate the matrices
with zeros
I1=A;
I=zeros(size(A));
I2=zeros(size(A));
%Filter Masks
F1=[0 1 0;1 4 1; 0 1 0];
F2=[1 1 1;1 8 1; 1 1 1];
%Padarray with zeros
A=padarray(A,[1,1]);
A=double(A);
%Implementation of the
equation in Fig.D
for i=1:size(A,1)2
for j=1:size(A,2)2
I(i,j)=sum(sum(F1.*A(i:i+2,j:j+2)));
end
end
I=uint8(I);
figure,imshow(I);title('Filtered
Image');
The Laplacian derivative equation has produced
grayish edge lines and other areas are made dark(background)
%Sharpenend Image
%Refer Equation in Fig.F
B=I1I;
figure,imshow(B);title('Sharpened
Image');
The
Filter Image is combined with the Original input image thus the background is
preserved and the sharpened image is obtained .
For a Filter Mask that includes Diagonal,
1

1

1

1

8

1

1

1

1

4 comments:
i dnt have computer vision toolbox in my matlab,without that vision cascade object detector is not possible,what can i do?
what about
I(i,j)=sum(sum(F1.*A(i:i+2,j:j+2)));
hey i want php code for Image Sharpening using second order derivative Laplacian transform...
I have a project on image mining..to detect the difference between two images, i ant to use the edge detection technique...so i want php code fot this image sharpening...
kindly help me
Hello.
Can you tell me why I get this error every time I run this.
Subscript indices must either be real positive integers or logicals.
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