how to give color for same pixel values?

i need to assign color for pixels having same value.. can anyone help me?

Answer 1

[Walter Roberson]

cmap = copper(22);     %some color map
outimg = ind2rgb( uint8(locatn), cmap);
image(outimg);

[sheno39]

sir this coding works for simple 5x5 matrix. but it is not working for image..

[sheno39]

sir can u help me to give different colors for different regions

Answer 2

[Image Analyst]

What do you mean by "pixels having the same value"? Do you mean, say, pixels having red color? And so you want to assign a green color to all pixels having "red" values? Meanwhile, why don't you look at my color segmentation demos in Image Analyst's awesome File Exchange?

[sheno39]

my input :

I=[...
2 3 10 4 6; 
1 4  7 5 3; 
5 2  8 4 3;
8 2  1 7 3;
1 9  8 3 4];
% Location of max pixel around each pixel is given as
locatn =[...
7  11  12  11  17;
3  11  11  11  21;
4  4  12  13  19;
10  10  10  13  19;
10  4  10  15  19;]

now i have to given same color for same values in 'locatn' matrix.

[Image Analyst]

I don't understand what it means when you say the location is 17 or 19 or 21. In a 2D image, there are immediate 8 neighbors. So I could possibly see a 1-8 if you define where they are located (like 1 is the upper left neighbor and you go around clockwise so that 8 is the left neighbor), but you have at least 21 locations. Where are they?

[sheno39]

I=[2 3 10 4 6; 1 4 7 5 3; 5 2 8 4 3;8 2 1 7 3;1 9 8 3 4;];
D = padarray(I,[1 1],0,'both');
s = size(I);
N = padarray(reshape(1:numel(I),s),[1 1],0,'both');
pt = [1 1 1;1 0 1;1 1 1] > 0;
s1 = s+2;
out = zeros(s);
for ii=2:s1(1)-1
    for jj=2:s1(2)-1
        D1 = D(ii-1:ii+1,jj-1:jj+1);
  K = N(ii-1:ii+1,jj-1:jj+1);
  K = K(pt);
        [~,i0] = max(D1(pt));
  out(ii-1,jj-1) = K(i0);
    end
end
s=[5,5];
[R C]=ind2sub(s,out);

Sir i have attached the coding here.

The values in 'out' have the locations i have mentioned above.

[Image Analyst]

But I still don't know what this uncommented code does. Can you tell me what a location of 21 means? Is it the linear index or something?

[sheno39]

yes sir it is linear indexing

[Image Analyst]

colormaps can only go up to 256 while linear indexes can far exceed that so you can't use a colormap. You'd have to create an RGB image from the linear index but I don't see how that would be meaningful. What you'll see is a gradient from upper left to lower right in color because, overall, that's how the linear indexes will go. How does that help?

[sheno39]

sir can u help me convert RGB image from linear index.

[sheno39]

 I used ind2rgb function. but i didn't get the correct output