在Matlab中计算图像段之间的接触长度

Question

我有四种颜色的图像。每种颜色代表一个特定的物质阶段。我可以根据颜色分割图像并计算分割图像的周长。现在，我需要计算不同相之间的接触长度。 An example of the image is shown here。例如，蓝相和黄相之间的接触长度很小，而蓝相和灰相有明显的接触。

% aa is the image  
oil = (aa(:,:,3)==255);
rock =(aa(:,:,2)==179);
gas =(aa(:,:,2)==255);
water =(aa(:,:,2)==0 && aa(:,:,3)==0);

O = bwboundaries(oil);
R = bwboundaries(rock);
G = bwboundaries(gas);
W = bwboundaries(water);

Answer 1

一种蛮力方法是遍历图像中的每个像素，并根据该像素值及其右侧像素的值，递增一个表示该相变接触长度计数的变量（如果存在）相变。然后对像素下方的值执行相同的操作。对图像中的每个像素执行此操作，边缘条件除外。

一种更有效的方法是一次执行行和列，并在执行此操作时递增计数器。

或者您可以制作图像的多个矩阵，移动一个像素，然后进行比较以查找最终得到二进制矩阵结果的相变，然后简单地将这些结果二进制矩阵相加

Answer 2

这是我最终编写的最终代码。结果看起来是正确的。

    % aa is the image  
oil = (aa(:,:,3)==255);
rock =(aa(:,:,2)==179);
gas =(aa(:,:,2)==255);
water =(aa(:,:,2)==0 && aa(:,:,3)==0);

phases(1,:,:)=RockBW;
phases(2,:,:)=WaterBW;
phases(3,:,:)=OilBW;
phases(4,:,:)=GasBW;

outMat = ContactMatrix(phases);

ContactMatrix函数如下所示：

function [ContactMat] = ContactMatrix(phases)
%CONTACTMATRIX measure the contact area between diferent phases

% The output is a 2D matrix which shows the lengths

%         Phase1, Phase2, Phase 3 
%phase1     L1      L2      L4
%Phase2     L2      L3      L5
%Phase3     L4      L5      L6

% L1 is zero
% L2 is the contact area of Phase1 and Phase2

nph = size(phases,1);

imSize = size(phases(1,:,:));
xmax =imSize(2);
ymax = imSize(3);
% Idealy we need a check for all sizes :) 
ContactMat = zeros(nph);

for i=1:1:nph
   counts = zeros(1,nph);
   dd2=bwmorph(squeeze(phases(i,:,:)),'dilate',1);
   B = bwboundaries(dd2);
   nB = size(B,1);
   coefs=1:1:nph;
   coefs(i)=[];
   for j=1:1:nB
        fd = B{j};
        % Ignore the points at boundary of image
        fd(fd(:,1)==1 | fd(:,1)==xmax | fd(:,2)==1 | fd(:,2)==ymax,:)=[];
        nL = size(fd,1);

        for k=1:1:nL(1)
            %bufCheck=false(nph-1,1);
               mat=fd(k,1) + (fd(k,2)-1)*xmax;
               bufCheck = phases(coefs,mat);
               counts(coefs)=counts(coefs)+bufCheck';
        end
   end 
   ContactMat(i,coefs)=counts(coefs);
end
ContactMat = 0.5*(ContactMat+ContactMat');
end