Convolution giving decimal point in the result

Hi,

Im trying to learn to look on the result from the kernel after convolution. Even i followed youtube for the double on the data but yet has a problem with the result.

Here is the code and the result, i don't know what else i had to change..

I = imread('C:\\MEKH\\LENA.jpg');
figure, imshow(I);
J=rgb2gray(I);
figure, imshow(J)
J=double(J)

A = [1,1,1;1,1,1;1,1,1]/9;

B = conv2(J,A,'same')
B=double(B)
figure, imshow(B)

Result:

Input
J =

   222   208   255   255   253
   105   141    82   108   169
   121   252     4     1   124
    89   124    79   195   227
   253   252   196   221   250


B =

   75.1111  112.5556  116.5556  124.6667   87.2222
  116.5556  154.4444  145.1111  139.0000  101.1111
   92.4444  110.7778  109.5556  109.8889   91.5556
  121.2222  152.2222  147.1111  144.1111  113.1111
   79.7778  110.3333  118.5556  129.7778   99.2222

Answer 1

[Ameer Hamza]

the output of conv2() is expected to be a fractional number. To use imshow, first convert it to uint8(). There are two alternatives

Convert the output of conv to uint8

I = imread('C:\\MEKH\\LENA.jpg');
figure, imshow(I);
J = rgb2gray(I);
figure, imshow(J)
J = double(J)
A = [1,1,1;1,1,1;1,1,1]/9;
B = conv2(J,A,'same')
B = uint8(B)
figure, imshow(B)

Or, use im2double() to convert the original image to double datatype

I = im2double(imread('C:\\MEKH\\LENA.jpg'));
figure, imshow(I);
J=rgb2gray(I);
figure, imshow(J)
A = [1,1,1;1,1,1;1,1,1]/9;
B = conv2(J,A,'same')
figure, imshow(B)

[Zamani Md Sani]

thanks for sharing your knowledge to me.. just a month learning matlab .. thanks

[Ameer Hamza]

I am glad to be of help!