Thread Subject: vectorization help please...

B is a two dimensional array (image). A is a cell array. Each cell of
A is a 5x5 array (a neigborhood). R and C contains row and column
indices of the centers of the neighborhoods. I want to assign (now
edited) neighborhoods back on to B:

for i=1:numel(R)
   B(R(i)-2:R(i)+2,C(i)-2:C(i)+2)= A{i};
end

can I get rid of 'for' loop? thx in advance.

ozizus <oguz@ce.yildiz.edu.tr> wrote in message <0d01631a-
f719-4396-95fa-4e5dfeec1cb3@u10g2000prn.googlegroups.com>...
> B is a two dimensional array (image). A is a cell array.
Each cell of
> A is a 5x5 array (a neigborhood). R and C contains row and
column
> indices of the centers of the neighborhoods. I want to
assign (now
> edited) neighborhoods back on to B:
>
> for i=1:numel(R)
> B(R(i)-2:R(i)+2,C(i)-2:C(i)+2)= A{i};
> end
>
> can I get rid of 'for' loop? thx in advance.

Here is an example with image Cameraman.tif.
   - Blocksize d = 20
   - Number of blocks: nblks = 4
   -

%% read image and initialize data
im = im2double(imread('cameraman.tif'));
nblks = 4;
% A = rand(d,d,nblks );
d = 15; %
A = squeeze(mat2cell(rand(d,d,nblks),d,d,ones(1,nblks)));
r = [30 20 50 150];
c = [20 50 30 200];

%% generate one reference block d x d

[cc,rr] = meshgrid(1:d);
cc = cc(:);
rr = rr(:);

dataf = cell2mat(A); % convert

%% generate locations of pixels in all blocks

x = rr(:,ones(1,nblks)) + r(ones(d^2,1),:)-(d+1)/2;
y = cc(:,ones(1,nblks)) + c(ones(d^2,1),:)-(d+1)/2;

%% fill data into image
imf = im;
imf(sub2ind(size(imf),x,y)) = dataf;

figure
imshow(imf)

By the way, you can use repmat, bsxfun, ...


HTH

Anh Huy Phan
RIKEN - BSI

ozizus <oguz@ce.yildiz.edu.tr> wrote in message <0d01631a-
f719-4396-95fa-4e5dfeec1cb3@u10g2000prn.googlegroups.com>...
> B is a two dimensional array (image). A is a cell array.
Each cell of
> A is a 5x5 array (a neigborhood). R and C contains row and
column
> indices of the centers of the neighborhoods. I want to
assign (now
> edited) neighborhoods back on to B:
>
> for i=1:numel(R)
> B(R(i)-2:R(i)+2,C(i)-2:C(i)+2)= A{i};
> end
>
> can I get rid of 'for' loop? thx in advance.

Here is an example with image Cameraman.tif.
   - Blocksize d = 20
   - Number of blocks: nblks = 4
   -

%% read image and initialize data
im = im2double(imread('cameraman.tif'));
nblks = 4;
% A = rand(d,d,nblks );
d = 15; %
A = squeeze(mat2cell(rand(d,d,nblks),d,d,ones(1,nblks)));
r = [30 20 50 150];
c = [20 50 30 200];

%% generate one reference block d x d

[cc,rr] = meshgrid(1:d);
cc = cc(:);
rr = rr(:);

dataf = cell2mat(A); % convert

%% generate locations of pixels in all blocks

x = rr(:,ones(1,nblks)) + r(ones(d^2,1),:)-(d+1)/2;
y = cc(:,ones(1,nblks)) + c(ones(d^2,1),:)-(d+1)/2;

%% fill data into image
imf = im;
imf(sub2ind(size(imf),x,y)) = dataf;

figure
imshow(imf)

By the way, you can use repmat, bsxfun, ...


HTH

Anh Huy Phan
RIKEN - BSI