labeling

I'm trying to do labeling after segmentation into four regions (white, light gray, dark gray and black) according to threshold method. This is the code:

clear all;

c = imread('image1_069.jpg'); 
a=double(c);
b = zeros(size(a));

b = uint8(a<90);
b(a >= 110) = 180;
b(a >= 150) = 200;
b(a >= 200) = 255;

figure(1);
imshow(b);

%Labeling
ImgLB=b;
ImgLB(1,:)=0; ImgLB(xsize,:)=0; ImgLB(:,1)=0;
ImgLB(:,ysize)=0; 
label=0;
for kx=2:xsize-1
    for ky=2:ysize-1
        W=zeros(3);
        W(1:3, 1:3)=ImgLB(kx-1:kx+1,ky-1:ky+1); 
        maxW=max(W(:));
        if ImgLB(kx, ky)==1 & ImgLB(kx,ky-1)==0 & maxW==1
            label=label+1;
            ImgLB(kx,ky)=label;
        end
        if ImgLB(kx,ky)==1 & maxW>=1
            ImgLB(kx,ky)=maxW;
        end
    end
end

figure(1)
subplot(1,3,1), imagesc(c),title ('Input')
subplot(1,3,2), imagesc(b), title('Threshold')
subplot(1,3,3), imagesc(unit8(ImgLB*255/max(max(ImgLB)))), title('Label')
colormap('gray');

loop=1;
while loop
    flag=0;
    for kx=2:xsize-1
        for ky=2:ysize-1
            if ImgLB(kx,ky)~=0 & ImgLB(kx+1,ky)~=0 & ImgLB(kx,ky)~=ImgLB(kx+1,ky)
              old=ImgLB(kx,ky);
              new=ImgLB(kx+1,ky);
              flag=1;
              break;
            end
        end
    end

if flag==0
    break;
end

for kx=2:xsize-1
    for ky=2:ysize-1
        if ImgLB(kx,ky)==old
            ImgLB(kx,ky)==new;
        end
    end
end
end

But, there is error at the line subplot(1,3,3), imagesc(unit8(ImgLB*255/max(max(ImgLB)))), title('Label')

I have no idea what's the mistake in that line. Is there any suggestion. This is the image I used: http://i41.tinypic.com/243glli.jpg

Answer 1

[Walter Roberson]

There is no MATLAB routine named "unit8". Perhaps you meant "uint8".

[Syahrul Niezam]

Thanks for your help.

However, there is error in line;

ImgLB(1,:)=0; ImgLB(xsize,:)=0; ImgLB(:,1)=0;

Is there anything mistake?

[Image Analyst]

Of course. You never defined xsize. Say, do you know how to use the debugger to set a breakpoint and hover the cursor over a variable to see its value, or look in the workspace to see its value? It's a crucial skill you must learn.

[Syahrul Niezam]

Thanks for your comment. I put this code into the 3rd line.

a=double(c(:,:,2))/255.0;

[xsize, ysize]=size(a);

Is there any mistake there? Where can I learn about the stuff that you mention above; set a breakpoint and hover the cursor over a varible?

Thanks in advance. :)

[Image Analyst]

There's a mistake there. You're confusing rows and columns with x and y. The size function gives rows and columns, in that order, which would be ysize and xsize. So the corrected code would be:

[ySize xSize numberOfColorChannels] = size(c);

if numberOfColorChannels > 1

a=double(c(:,:,2))/255.0;

else

a=double(c)/255.0;

end

You can learn about debugging in the help file somewhere, I'm sure.

[Syahrul Niezam]

I'm sorry, which line should i change the codes?

Answer 2

[Syahrul Niezam]

Thanks for your help. However, there is error in line;

ImgLB(1,:)=0; ImgLB(xsize,:)=0; ImgLB(:,1)=0;

Is there anything mistake?