如何区分黑白棋盘广场

Question

我想自动化将棋盘图像的方块分类为黑色或白色方块的过程。进一步的步骤是区分它是否为空方格或方块是否包含一块。到目前为止，我接近使用平方中心的平均强度将每个方块分类为白​​色或黑色，但设置阈值很困难。对于更进一步的步骤（空方格或一块），我尝试std2，但也很难。

这是我的原始图像，以及到目前为止我接近的内容

这是我的剧本：

image = imerode(original,strel('disk',3));
image = imadjust(image,[],[],2);
figure,imshow(image),hold on;
for i = 1:length(cells)
  TL = cells(i).TL; %Cell's corner top left
  TR = cells(i).TR; %Cell's corner top right
  BL = cells(i).BL; %Cell's corner bottom left
  BR = cells(i).BR; %Cell's corner bottom right
  x = [TL(1) TR(1) BR(1) BL(1)];
  y = [TL(2) TR(2) BR(2) BL(2)];
  bw = poly2mask(x,y,size(image,1),size(image,2));
  measurements = regionprops(bw,'BoundingBox');
  cropped = imcrop(image, measurements.BoundingBox);
  m = regionprops(bw,'Centroid');
  x = m.Centroid(1);
  y = m.Centroid(2);
  w = 25; %width
  h = 25; %height
  tl = [round(x-w/2) round(y-h/2)];
  center = image(tl(1):tl(1)+w,tl(2):tl(2)+h,:);
  %stds(i) = std2(center);
  avgs(i) = mean2(center);
  if(avgs(i) > 55)
      str = "W";
  else
      str = "B";
  end
  text(x,y,str,'Color','red','FontSize',16);
end

编辑：以下图片是

之后的新结果

image = imerode(image,strel('disk',4));
image = image>160;

Answer 1

您可以在棋盘方法detectCheckerboardPoints和checkerboard中使用Matlabs构建来查找棋盘格的大小并构建一个合适大小的棋盘格。由于只能存在两个可能的棋盘格，因此构造两个并检查哪一个与最佳匹配。

img = imread('PNWSv.jpg'); %Load image

%Prepare image
I = rgb2gray(img);
I2 = imerode(I,strel('square',10));
bw = imbinarize(I2,'adaptive');

%Find checkerboard points
[imagePoints,boardSize] = detectCheckerboardPoints(bw);

%Find the size of the checkerboard fields
x = boardSize(2)-1;
y = boardSize(1)-1;
fields = cell(y,x);
for k = 1:length(imagePoints)
    [i,j] = ind2sub([y,x],k);
    fields{i,j} = imagePoints(k,:);
end
avgDx = mean(mean(diff(cellfun(@(x) x(1),fields),1,2)));
avgDy = mean(mean(diff(cellfun(@(x) x(2),fields),1,1)));

%Construct the two possibilities
ref1 = imresize(imbinarize(checkerboard),[avgDx,avgDy]*8);
ref2 = imcomplement(ref1);

%Check which ones fits the better
c1 = normxcorr2(ref1,I);
c2 = normxcorr2(ref2,I);

if max(c2(:))<max(c1(:))
    ref=ref1;
    c = c1;
else 
    ref=ref2;
    c = c2;
end

%Plot the checkerboard bounding box on top of the original image
[ypeak, xpeak] = find(c==max(c(:)));
yoffSet = ypeak-size(ref,1);
xoffSet = xpeak-size(ref,2);

imshow(img);
imrect(gca, [xoffSet+1, yoffSet+1, size(ref1,2), size(ref1,1)]); 

Answer 2

侵蚀然后二值化将帮助您找到空的白色方块。

通过这些，您可以更轻松地重建整个棋盘网格并估计占用的正方形。