How to solve error A filename must be supplied in imwrite?

I have multiple rgb images in a folder and i want to convert them into gray scale and the save them into another folder

code

ImageFolder = "D:\sys2\New folder\8PSK\8PSK"
imds = imageDatastore('D:\sys2\New folder\8PSK\*.png')  % Whatever...
numberOfImages = length(imds.Files)
for k = 1 : numberOfImages    
  % Get the input filename.  It already has the folder prepended so we don't need to worry about that.
    inputFileName = imds.Files{k};
    fprintf('Checking %s\n', inputFileName);
    rgbImage = imread(inputFileName);
    grayImage = rgb2gray(rgbImage);
    imshow(grayImage);
    file_name = sprintf('Image%d.png', k)% name Image with a sequence of number, ex Image1.png , Image2.png....
    fullFileName = fullfile(ImageFolder, file_name);
    imgName = [ImageFolder,'\Image_',num2str(k),'.png'] ;
    imwrite(grayImage,imgName) ; 

    axis('on', 'image');
    drawnow;
    pause(0.1); % Short delay so we can see the image a little bit.
end
msgbox('Done!');

error

Error using imwrite>parse_inputs (line 610)
A filename must be supplied.

Error in imwrite (line 440)
[data, map, filename, format, paramPairs] = parse_inputs(varargin{:});

Please help

[KSSV]

Check what does imgName give?

[john karli]

1x4 string

"D:\sys2\New folder\8PSK\8PSK" "\Image_" " 1 " " .png"

[Stephen23]

@john karli: what MATLAB version are you using?

[john karli]

MATLAB R2021a

[DGM]

You're giving imwrite a vector of multiple strings. Unless behavior has changed since the version I'm using, that's not a valid input.

Answer 1

[yanqi liu]

sir，please check the follow code to get some information

for more information,you can read the book 《计算机视觉与深度学习实战》，Thank you！

ImageFolder = "D:\sys2\New folder\8PSK\8PSK"
imds = imageDatastore('D:\sys2\New folder\8PSK\*.png')  % Whatever...
numberOfImages = length(imds.Files)
for k = 1 : numberOfImages    
  % Get the input filename.  It already has the folder prepended so we don't need to worry about that.
    inputFileName = imds.Files{k};
    fprintf('Checking %s\n', inputFileName);
    rgbImage = imread(inputFileName);
    grayImage = rgb2gray(rgbImage);
    imshow(grayImage);
    file_name = sprintf('Image%d.png', k)% name Image with a sequence of number, ex Image1.png , Image2.png....
    fullFileName = fullfile(ImageFolder, file_name);
    
    imgName = fullfile(ImageFolder,['Image_',num2str(k),'.png']);
    disp(imgName);
    [fd,~,~] = fileparts(imgName);
    if ~exist(fd)
        mkdir(fd);
    end
    
    imwrite(grayImage,imgName) ; 

    axis('on', 'image');
    drawnow;
    pause(0.1); % Short delay so we can see the image a little bit.
end
msgbox('Done!');

[john karli]

it works

what was the problem?

[yanqi liu]

sir，i think may be the character not satisfied

[john karli]

OK