How to generate a bitmap image without using function...Please help

How can i generate bitmap representation of an image using thresholding?? below code didn't work....

 for i=1:r
    for j=1:s
         thresh=C(i,j)+Di;    
         if(imean(i,j)>=thresh)
            bm(i,j)=1;
         else
            bm(i,j)=0;
         end
     end
 end
 figure
 imshow(bm);

[Sreeda M A]

I am getting an error like this :

Attempted to access C(2,1); index out of bounds because size(C)=[1,256].

Error in content (line 51)
       thresh=C(i,j)+Di;

[Geoff Hayes]

Sreeda - how are r and s initialized? You are trying to iterate over C which is a 1x256 matrix yet r is at least two. Please clarify where these values have come from and how they relate to C.

[Sreeda M A]

r and s are size of image....256*256 respectively

[Stephen23]

@Sreeda M A: Don't waste your time writing loops. MATLAB is a high-level language, so you don't need to mess around with ugly loops. See Walter Roberson's answer for the simplest and fastest solution.

[Walter Roberson]

If r and s are the size of your image, then your image is stored in some variable other than C.

[Sreeda M A]

I changed the code as shown below

imean=padarray(imean,[3,3],0);
for i=1:256
    for j=1:256
        m1=imean(i:i+2,j:j+2);
        thresh=n1(i,j)+sod;    
if(m1(i,j)>=thresh)
    bm(i,j)=1;
else
    bm(i,j)=0;
end
    end
end

Here imean is an interband average image,n1 is the minimum of that image and sod is scaled version of dither array......

[Image Analyst]

I fixed your formatting for you, but please read this.

Also to do a locally adaptive threshold like you did, you can do it vectorized if you just create an m1 (or n1) image with conv2() or imfilter(), then use >=. Let me know if you can't figure it out.

bm =

[Sreeda M A]

Sorry sir ,but I can't figure it out .

Answer 1

[Walter Roberson]

thresh = C + Di;
bm = imean >= thresh;

No loop required.