how to subtract a dynamic mask from an image

how to subtract a dynamic mask from an image. i m using the following code but its only working on static mask.

f=[12 30 120 220 120 130 140 150 120 220 120 120 90 80 70 80]
[r c]=size(f);
m=f(3:5)
f1 =[];
for i=1:r
for j=1:c
sub_result=abs(f(i,j)-m);
f1(i,j)=sum(sub_result(:));
end
end

[Image Analyst]

I don't understand. How is the mask dynamic, that is, how are the numbers in the 1-by-2 window changing with position of the mask? Is it [5,8] when the mask is over the [12,30], then when the mask has moved over one location the mask is now [8,3] while it's over [30, 120], and then (moving over another element) the mask is now [3,4] when it's over [120, 220]? Is that what you mean?

Or is the mask just [3,4] no matter where it's positioned over your "f" vector? If so, then what is that [5,8,3,4,6,7,9,3] vector and how does it relate to the "f" vector?

[Hanif Ullah]

dynamic mean that mask size is changing. like [3 4] is one mask and another mask size is [3 4 5] or may be bigger but less than original matric size.

[Image Analyst]

I think you're going to have to do that manually. There is no built-in function that will scan a mask over a vector when the size and values of the mask change from element to elment as it moves over the vector to be filtered.

Answer 1

[KSSV]

Are you looking for something like this?

I = [5 8 3 4 6 7 9 3] ; 
M = [3 4] ; 
M = repmat(M,1,length(I)/length(M)) ;
iwant = I-M

[Hanif Ullah]

No sir I dont want to use repmat function. i want to apply loops and subtraction

[KSSV]

Why loop when you can achieve this?

[Hanif Ullah]

actually repmat subtracting block by block. I want that mask subtract shift/move pixel by pixel using loop