CODEWITHSUNDEEP
matlabimage-processing
HIM
HIM

Reputation: 17

Matlab change a set of images to 2D grayscale but error occur

I was trying to turn a set of images to 2D grayscale image in order to do Surf feature extraction. In the set, some of the images are already in 2D scale so when I tried to run a loop. This error message happens: MAP must be a m x 3 array.

Here is my code:

for ii=1:numImages
   
   img = readimage(imdsTrain,ii);
   RGB = rgb2gray(img)

   points = detectSURFFeatures(RGB);
   [surf1, valid_points] = extractFeatures(RGB, points);
   figure; imshow(RGB); hold on;
   plot(valid_points.selectStrongest(10),'showOrientation',true);
   title ('Ct-scan image with Surf feature')
 
end;

Is there any solution that can solve this problem?

Upvotes: 0

Views: 85

Answers (1)

paisanco
paisanco

Reputation: 4164

Matlab's rgb2gray will fail if you give it a grayscale image (an image with only one color channel).

If you are sure that your images are either m x n X 3 or m x n x 1, you could check for the m x n x 3 case before attempting to do the rgb2gray. If your image is already a grayscale image no conversion is needed or can be done via rgb2gray.

Something like this:

img = readimage(imdsTrain,ii);
[rows, columns, colors]  = size(img)
if colors > 1
   RGB = rgb2gray(img)
end

Now getting the error MAP must be a m x 3 array suggests that whatever you supplied rgb2gray got interpreted as a colormap. So I would check if all your images are indeed three dimensions, as you are assumimg.

Upvotes: 1

Related Questions