Apply a function to each block of an image

Question

NC 2018-6-28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/407843-apply-a-function-to-each-block-of-an-image

I divide the input image into blocks of 57*57 and then apply the function "emresample" to each block and draw the probability map and periodicity map. For that I used the following functions. Then I got the error Undefined function or variable 'pmap'.Error in blockofImageNew (line 11)pmap2 = pmap;. How to solve it ?

.m

     function [Pmap,cen,RN,RS,Y,varargout] = emresample(img,N,varargin)
     RN = 0;
     RS = 0; 
     MAXITER = 100;
     EPSILON = 1e-3;
     MAXBLOCKS = 3.5e3;
     p0 = 1/256;
    if(size(img,3)~=1)
      error('Image must be grayscale.')
    end
    if(nargin>2)
    verbose = (varargin{1}=='verbose');
    else
      verbose = 0;
    end
     wlen = 2*N+1; % window length
     cen = floor(wlen^2/2) + 1;  % center element
     [height width] = size(img);
    imcol = im2col(img,[wlen wlen]);
    [~,nblocks] = size(imcol);
    Y = imcol';
    Y(:,cen) = []; % delete center element
    fprintf('imcol :');
    % initialize parameters
    alpha = rand(1,wlen^2-1)';
    alpha = alpha./sum(alpha(:)); % normalize weights
    sigma = 0.75;
     y = img(N+1:end-N,N+1:end-N);
     y = y(:);
    idx_rand = randperm(nblocks);
    idx = idx_rand(1:min(MAXBLOCKS,nblocks));
    Yt = Y(idx,:);
    yt = y(idx,:);
    if(verbose==1)
       fprintf('Current EM Iteration\n')
    end
    for iter = 1:MAXITER    
      prev = alpha;
    if(verbose==1)
        disp(iter)
    end
     % E-step
     R = yt - Yt*alpha;  % find residuals
     P = 1/(sigma*sqrt(2*pi)) * exp(-R.^2/(2*sigma.^2)); 
     w = P./(P+p0);                                       
     RN = (RN+R(MAXITER))/length(R);
     RS= RS+R(MAXITER);
     % M-step                   
     sigma = sqrt( sum(w.*R.^2)/sum(w) );     
     alpha = (Yt'*diag(w)*Yt) \ Yt'*diag(w)*yt;    %new alpha
     if(max(abs(prev-alpha))<EPSILON)
        break;
     end
     end
     if(verbose==1)    
     fprintf('Number of iterations = %i\n',iter);
     fprintf('sigma = %.5f\n',sigma);
     end
     Pmap = 1/(sigma*sqrt(2*pi)) * exp(-(y-Y*alpha).^2/(2*sigma.^2)); 
     Ndecimals = 2 ;
     f = 10.^Ndecimals ; 
     Pmap= round(f*Pmap)/f ;
    Pmap = reshape(Pmap,[height-2*N width-2*N]);
    fprintf('Pmap Value : ');
    disp(Pmap);
    % optional outputs
    if(nargout==1)
     varargout{1} = alpha;
    elseif(nargout==2)
    varargout{1} = alpha;
    varargout{2} = sigma;
    elseif(nargout==3)
    varargout{1} = alpha;
    varargout{2} = sigma;
    varargout{3} = iter;
    end
   %%YourFunction2.m
    function [result,pmap,fmap] = YourFunction(block_of_image)
    N=2
    [Pmap,fmap] = emresampleN(block_of_image,N,'verbose');                  
    fmap = fft2c(Pmap);
    result = fft2c(Pmap);
    %%script.m
    clc;
    clear all;
    close all;
    img = imread('Original\ucid\ImageDataSet\ucid00320sp.tif');
    img = rgb2gray(img);
    img= double(img);
    aux_fun = @(block_info) YourFunction2(block_info.data);
     result = blockproc(img,[57 57], aux_fun, 'TrimBorder', false)
     pmap2 = Pmap;
     fmap2 = fmap;
    subplot(2, 3, 3);
    imshow(img);
    figure;
    subplot(131)
     imshow(img,[])
     subplot(132)
     imshow(pmap2,[])
     subplot(133)