converting tiff file to grey scale using im2gray error at position 1

I try to convert my tiff files to grey scale images. I read that I should use im2grey. But I get an error that there is an invaling argument at position 1 and that the value must be numeric. What does this mean?

Answer 1

[Walter Roberson]

You have to read the data in first; you cannot pass in a file name

img = imread('flamingos.jpg');
grimg = im2gray(img);

imshow(grimg)

[Lotte van Dijk]

I thought that the problem was that i could not read the image first since the left side was x by x and the right side x by x by 3 which meant that i should convert it first to a gray image. this is the initial problem do you know how i could solve this.

[Walter Roberson]

Example:

for K = 1 : 5
   filename = sprintf('img%05d.tiff', K);
   outputs(:,:,K) = im2gray(imread(filename));
end

[Lotte van Dijk]

That worked thank you!