裁剪文件夹中的图像 - Matlab

Question

我正在尝试编写一个脚本来读取文件夹中的所有 JPG 图像并根据此脚本裁剪它们：

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

但我收到此错误：

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);

如果我在单个图像上应用循环内部，它可以正常工作。

知道我做错了什么吗？

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，如果有，请相应地调用rgb2gray。此外，rgb2gray 需要 图像，但您提供的是字符串：

grayImage = rgb2gray(fullFileName);

先用imread读入图片，再在这张图片上用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