如何在Matlab中獲取一組x和y坐標的灰度值？

Question

使用此代碼：

gray = rgb2gray(I5);
imtool(gray)
graydata = 0;
graydata = gray(sub2ind(size(gray)),(y(:)),(x(:)));

我收到以下錯誤：

Error in fourierdescriptorscode (line 18)

這是第18行：

graydata = gray(sub2ind(size(gray)),(y(:)),(x(:))); 

Answer 1

要獲取特定x和y坐標的值，只需將其作為指標即可。 例如，您要像素第2行，第3列

pixel_of_interest = gray(2,3);

如果您有索引並想要獲取對應的行列val

[row_of_interest, col_of_interest] = ind2sub(size(gray),INDEX_OF_INTEREST); 

Answer 2

看來您放錯了括號。 sub2ind至少需要3個參數：

graydata = gray(sub2ind(size(gray)),(y(:)),(x(:)));
                        move this ^             ^ after this...
graydata = gray(sub2ind(size(gray),(y(:)),(x(:))));