在文件夹中裁剪图像-Matlab

Question

我正在尝试编写一个脚本，该脚本读取文件夹中的所有JPG图像并根据此脚本进行裁剪：

myFolder = 'D:/Temp/';
filePattern = fullfile(myFolder, '*.jpg');
jpegFiles = dir(filePattern);

for k = 1:length(jpegFiles)
    baseFileName = jpegFiles(k).name;
    fullFileName = fullfile(myFolder, baseFileName); 
    %// show image   
    imshow(fullFileName)
    %// Make a binary image
    grayImage = rgb2gray(fullFileName);
    binaryImage = grayImage < 250;

    [y,x] = find(binaryImage);  %// Find row and column locations that are non-zero
    %// Find top left corner
    xmin = min(x(:));
    ymin = min(y(:));
    %// Find bottom right corner
    xmax = max(x(:));
    ymax = max(y(:));
    %// Find width and height
    width = xmax - xmin + 1;
    height = ymax - ymin + 1;
    %// Crop image
    outputImage = imcrop(fullFileName, [xmin ymin width height]);
    imshow(outputImage);
end

但是我得到这个错误：

Warning: Image is too big to fit on screen; displaying at 67% 
> In images.internal.initSize (line 71)
  In imshow (line 305)
  In Untitled2 (line 9) 
Error using rgb2gray>parse_inputs (line 82)
MAP must be a m x 3 array.

Error in rgb2gray (line 37)
X        = parse_inputs(X);

Error in Untitled2 (line 11)
grayImage = rgb2gray(fullFileName);

如果我将循环的内部应用于单个图像，则效果很好。

知道我在做什么错吗？

Answer 1

这可能意味着您的某些图像不是 RGB，而是灰度/单通道。 您可以通过添加检查以查看读入的图像是否具有三个通道来解决此问题，如果存在，请相应地调用rgb2gray 。 另外， rgb2gray需要一个image ，但是您正在提供一个字符串：

grayImage = rgb2gray(fullFileName);

首先使用imread读取图像，然后在此图像上使用rgb2gray ：

for k = 1:length(jpegFiles)
    baseFileName = jpegFiles(k).name;
    fullFileName = fullfile(myFolder, baseFileName); 
    %// show image   
    imshow(fullFileName)

    %// Read in image first
    img = imread(fullFileName);

    %// Make a binary image
    if size(img,3) == 3
        grayImage = rgb2gray(img);
    else
        grayImage = img;
    end

    %//....
    %//rest of your code here

end