how to convert tiff image into gray image?
59 views (last 30 days)
Show older comments
how to convert tiff image into gray image? I tried rgb2gray but it show me an error about "RGB must be a m x n x 3 array" my tiff image is (m x n x 4)
1 Comment
Svetlana Zeveleva
on 22 Mar 2018
I'm having the same issue. But how did you find out the array size of your image?
Accepted Answer
Guillaume
on 20 Sep 2014
Your image has a transparency channel in addition to the three colour channels. If you don't want to do anything with the transparency information, just discard it:
img(:,:,4) = [];
%proceed with rgb2gray
4 Comments
Guillaume
on 20 Sep 2014
You can just save the grayscale image as tiff. If you wanted to convert it to rgb, it simply would be:
rgbimg = repmat(img, [1 1 3]);
And if you wanted a non-transparent transparency channel
rgbaimg = [repamt(img, [1 1 3]) zeros(size(img))];
There wouldn't be much point in either though.
Image Analyst
on 20 Sep 2014
What do you mean "again"? Once it's in memory, it's just a 2D array of numbers. You can save the gray image out to a grayscale tiff image with imwrite:
filename = fullfile(folder, 'mygrayScaleTiff.tif');
imwrite(grayImage, filename);
If you want to save your RGB image, without the 4th channel which you removed and before you converted to grayscale and did other stuff, as an RGB image, you can (using Guillaume's code) save it with imwrite() like this:
filename = fullfile(folder, 'myRGBTiff.tif');
imwrite(img, filename);
More Answers (0)
See Also
Categories
Find more on Image Processing Toolbox in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!