隔离矩形物体的最佳方法

Question

我有以下图像，我想在中间分割矩形对象。我实现了以下代码来分段，但我无法隔离对象。我可以采取哪些功能或方法来隔离图像中的矩形对象？

im = imread('image.jpg');

% convert image to grayscale,
imHSV = rgb2hsv(im);
imGray = rgb2gray(im);
imSat = imHSV(:,:,2);
imHue = imHSV(:,:,1);
imVal = imHSV(:,:,3);

background = imopen(im,strel('disk',15));

I2 = im - background;

% detect edge using sobel algorithm
[~, threshold] = edge(imGray, 'sobel');
fudgeFactor = .5;
imEdge = edge(imGray,'sobel', threshold * fudgeFactor);
%figure, imshow(imEdge);

% split image into colour channels
redIM   = im(:,:,1);
greenIM = im(:,:,2);
blueIM  = im(:,:,3);

% convert image to binary image (using thresholding)
imBlobs = and((imSat < 0.6),(imHue < 0.6));
imBlobs = and(imBlobs, ((redIM + greenIM + blueIM) > 150));
imBlobs = imfill(~imBlobs,4);
imBlobs = bwareaopen(imBlobs,50);

figure,imshow(imBlobs);

Answer 1

在这个例子中，您可以利用矩形在其所有角落中都包含蓝色的事实，以便构建一个良好的初始蒙版。

1. 使用阈值来定位图像中的蓝色位置并创建初始遮罩。
2. 鉴于此初始遮罩，使用最小和最大操作找到它的角落。
3. 在角落之间用线条连接以接收矩形。
4. 使用imfill填充矩形。

代码示例：

% convert image to binary image (using thresholding)
redIM   = im(:,:,1);
greenIM = im(:,:,2);
blueIM  = im(:,:,3);
mask = blueIM > redIM*2 & blueIM > greenIM*2; 
%noise cleaning
mask = imopen(mask,strel('disk',3));

%find the corners of the rectangle
[Y, X] = ind2sub(size(mask),find(mask));
minYCoords = find(Y==min(Y));
maxYCoords = find(Y==max(Y));
minXCoords = find(X==min(X)); 
maxXCoords = find(X==max(X));
%top corners
topRightInd = find(X(minYCoords)==max(X(minYCoords)),1,'last');
topLeftInd = find(Y(minXCoords)==min(Y(minXCoords)),1,'last');
p1 = [Y(minYCoords(topRightInd)) X((minYCoords(topRightInd)))];
p2 = [Y(minXCoords(topLeftInd)) X((minXCoords(topLeftInd)))];
%bottom corners
bottomRightInd = find(Y(maxXCoords)==max(Y(maxXCoords)),1,'last'); 
bottomLeftInd = find(X(minYCoords)==min(X(minYCoords)),1,'last');
p3 = [Y(maxXCoords(bottomRightInd)) X((maxXCoords(bottomRightInd)))];
p4 = [Y(maxYCoords(bottomLeftInd)) X((maxYCoords(bottomLeftInd)))]; 

%connect between the corners with lines
l1Inds = drawline(p1,p2,size(mask));
l2Inds = drawline(p3,p4,size(mask));
maskOut = mask;
maskOut([l1Inds,l2Inds]) = 1;

%fill the rectangle which was created
midP = ceil((p1+p2+p3+p4)./4);
maskOut = imfill(maskOut,midP);

%present the final result
figure,imshow(maskOut);

最终结果：

中间结果（阈值取1次后，加入线后2次）：

* drawline函数取自drawline webpage