提取边界内的图像区域

我必须使用 2D CT 图像做一个项目，并使用 Matlab（仅）对其中的肝脏和肿瘤进行分割。最初我必须单独分割肝脏区域。我使用区域生长进行肝脏分割。它获取种子点作为输入。

输出是具有肝脏区域边界的图像。现在我需要仅由边界包围的区域。

我的程序有一个主程序和一个regionGrowing.m函数。因为我是新用户，所以不允许发布图片。如果你确实需要图片我会发邮件给你。请帮助我。

  % mainreg.m

  IR=imread('nfliver5.jpg');
  figure, imshow(IR), hold all
  poly = regionGrowing(IR,[],15,1200); % click somewhere inside the liver
  plot(poly(:,1), poly(:,2), 'LineWidth', 2, 'Color', [1 1 1])

%regionGrowing.m

function [P, J] = regionGrowing(cIM, initPos, thresVal, maxDist, tfMean, tfFillHoles, tfSimplify)
% REGIONGROWING Region growing algorithm for 2D/3D grayscale images
%
% Syntax:
%   P = regionGrowing();
%   P = regionGrowing(cIM);
%   P = regionGrowing(cIM, initPos)
%   P = regionGrowing(..., thresVal, maxDist, tfMean, tfFillHoles, tfSimpl)
%   [P, J] = regionGrowing(...);
%
% Inputs:
%          cIM: 2D/3D grayscale matrix                      {current image}
%      initPos: Coordinates for initial seed position     {ginput position}
%     thresVal: Absolute threshold level to be included     {5% of max-min}
%      maxDist: Maximum distance to the initial position in [px]      {Inf}
%       tfMean: Updates the initial value to the region mean (slow) {false}
%  tfFillHoles: Fills enclosed holes in the binary mask              {true}
%   tfSimplify: Reduces the number of vertices {true, if dpsimplify exists}
%
% Outputs:
%   P: VxN array (with V number of vertices, N number of dimensions)
%      P is the enclosing polygon for all associated pixel/voxel
%   J: Binary mask (with the same size as the input image) indicating
%      1 (true) for associated pixel/voxel and 0 (false) for outside
%   
% Examples:
%   % 2D Example
%   load example
%   figure, imshow(cIM, [0 1500]), hold all
%   poly = regionGrowing(cIM, [], 300); % click somewhere inside the lungs
%   plot(poly(:,1), poly(:,2), 'LineWidth', 2)
%   
%   % 3D Example
%   load mri
%   poly = regionGrowing(squeeze(D), [66,55,13], 60, Inf, [], true, false);
%   plot3(poly(:,1), poly(:,2), poly(:,3), 'x', 'LineWidth', 2)
%
% Requirements:
%   TheMathWorks Image Processing Toolbox for bwboundaries() and axes2pix()
%   Optional: Line Simplification by Wolfgang Schwanghart to reduce the 
%             number of polygon vertices (see the MATLAB FileExchange)
%
% Remarks:
%   The queue is not preallocated and the region mean computation is slow.
%   I haven't implemented a preallocation nor a queue counter yet for the
%   sake of clarity, however this would be of course more efficient.
%
% Author:
%   Daniel Kellner, 2011, braggpeaks{}googlemail.com
%   History: v1.00: 2011/08/14


% error checking on input arguments
if nargin > 7
    error('Wrong number of input arguments!')
end

if ~exist('cIM', 'var')
    himage = findobj('Type', 'image');
    if isempty(himage) || length(himage) > 1
        error('Please define one of the current images!')
    end

    cIM = get(himage, 'CData');
end

if ~exist('initPos', 'var') || isempty(initPos)
    himage = findobj('Type', 'image');
    if isempty(himage)
        himage = imshow(cIM, []);
    end

    % graphical user input for the initial position
    p = ginput(1);

    % get the pixel position concerning to the current axes coordinates
    initPos(1) = round(axes2pix(size(cIM, 2), get(himage, 'XData'), p(2)));
    initPos(2) = round(axes2pix(size(cIM, 1), get(himage, 'YData'), p(1)));
end

if ~exist('thresVal', 'var') || isempty(thresVal)
    thresVal = double((max(cIM(:)) - min(cIM(:)))) * 0.05;
end

if ~exist('maxDist', 'var') || isempty(maxDist)
    maxDist = Inf;
end

if ~exist('tfMean', 'var') || isempty(tfMean)
    tfMean = false;
end

if ~exist('tfFillHoles', 'var')
    tfFillHoles = true;
end

if isequal(ndims(cIM), 2)
    initPos(3) = 1;
elseif isequal(ndims(cIM),1) || ndims(cIM) > 3
    error('There are only 2D images and 3D image sets allowed!')
end

[nRow, nCol, nSli] = size(cIM);

if initPos(1) < 1 || initPos(2) < 1 ||...
   initPos(1) > nRow || initPos(2) > nCol
    error('Initial position out of bounds, please try again!')
end

if thresVal < 0 || maxDist < 0
    error('Threshold and maximum distance values must be positive!')
end

if ~isempty(which('dpsimplify.m'))
    if ~exist('tfSimplify', 'var')
        tfSimplify = true;
    end
    simplifyTolerance = 1;
else
    tfSimplify = false;
end


% initial pixel value
regVal = double(cIM(initPos(1), initPos(2), initPos(3)));

% text output with initial parameters
disp(['RegionGrowing Opening: Initial position (' num2str(initPos(1))...
      '|' num2str(initPos(2)) '|' num2str(initPos(3)) ') with '...
      num2str(regVal) ' as initial pixel value!'])

% preallocate array
J = false(nRow, nCol, nSli);

% add the initial pixel to the queue
queue = [initPos(1), initPos(2), initPos(3)];


%%% START OF REGION GROWING ALGORITHM
while size(queue, 1)
  % the first queue position determines the new values
  xv = queue(1,1);
  yv = queue(1,2);
  zv = queue(1,3);

  % .. and delete the first queue position
  queue(1,:) = [];

  % check the neighbors for the current position
  for i = -1:1
    for j = -1:1
      for k = -1:1

        if xv+i > 0  &&  xv+i <= nRow &&...          % within the x-bounds?
           yv+j > 0  &&  yv+j <= nCol &&...          % within the y-bounds?          
           zv+k > 0  &&  zv+k <= nSli &&...          % within the z-bounds?
           any([i, j, k])       &&...      % i/j/k of (0/0/0) is redundant!
           ~J(xv+i, yv+j, zv+k) &&...          % pixelposition already set?
           sqrt( (xv+i-initPos(1))^2 +...
                 (yv+j-initPos(2))^2 +...
                 (zv+k-initPos(3))^2 ) < maxDist &&...   % within distance?
           cIM(xv+i, yv+j, zv+k) <= (regVal + thresVal) &&...% within range
           cIM(xv+i, yv+j, zv+k) >= (regVal - thresVal) % of the threshold?

           % current pixel is true, if all properties are fullfilled
           J(xv+i, yv+j, zv+k) = true; 

           % add the current pixel to the computation queue (recursive)
           queue(end+1,:) = [xv+i, yv+j, zv+k];

           if tfMean
               regVal = mean(mean(cIM(J > 0))); % --> slow!
           end

        end        
      end
    end  
  end
end
%%% END OF REGION GROWING ALGORITHM


% loop through each slice, fill holes and extract the polygon vertices
P = [];
for cSli = 1:nSli
    if ~any(J(:,:,cSli))
        continue
    end

    % use bwboundaries() to extract the enclosing polygon
    if tfFillHoles
        % fill the holes inside the mask
        J(:,:,cSli) = imfill(J(:,:,cSli), 'holes');    
        B = bwboundaries(J(:,:,cSli), 8, 'noholes');
    else
        B = bwboundaries(J(:,:,cSli));
    end

    newVertices = [B{1}(:,2), B{1}(:,1)];

    % simplify the polygon via Line Simplification
    if tfSimplify
        newVertices = dpsimplify(newVertices, simplifyTolerance);        
    end

    % number of new vertices to be added
    nNew = size(newVertices, 1);

    % append the new vertices to the existing polygon matrix
    if isequal(nSli, 1) % 2D
        P(end+1:end+nNew, :) = newVertices;
    else                % 3D
        P(end+1:end+nNew, :) = [newVertices, repmat(cSli, nNew, 1)];
    end
end

% text output with final number of vertices
disp(['RegionGrowing Ending: Found ' num2str(length(find(J)))...
      ' pixels within the threshold range (' num2str(size(P, 1))...
      ' polygon vertices)!'])

如果我理解正确的话，您有一个肾脏边界的二值图像，现在需要将边界内部设置为 1 秒。为此，您可以使用imfill() http://www.mathworks.com/help/toolbox/images/ref/imfill.html功能与“孔”设置打开。

BW2 = imfill(BW,'holes');

编辑：看看代码，它似乎已经满足了您的要求。

% Outputs:
%   J: Binary mask (with the same size as the input image) indicating
%      1 (true) for associated pixel/voxel and 0 (false) for outside

所以你只需要得到第二个输出：

  IR=imread('nfliver5.jpg');
  figure, imshow(IR), hold all
  [poly im] = regionGrowing(IR,[],15,1200); % click somewhere inside the liver
  imshow(im,[])

Now im是带有分割区域的二值图像。

EDIT2:

一旦你有了二值图像im，您可以简单地使用逐元素乘法来删除分割区域之外的原始图像的所有部分。

SEG = IR.*im;
imshow(SEG,[]) 

EDIT3:

对于 3D 图像，您需要手动指定坐标，而不是使用鼠标。这是因为鼠标只给我们 2 个坐标（x 和 y），而您需要 3 个坐标（x、y 和 z）。因此，只需通过查看图像找到所需的坐标，然后选择合适的 z 坐标即可。

%Example coordinates, 
coordinates = [100 100 5] 
poly = regionGrowing(squeeze(IR), coordinates, 60, Inf, [], true, false);