How can i normalize a greyscale image?

Hello ,

I've seen many similar questions but i am still confused . I have a grayscale image and i want to normalize it.How can i do that ? I have seen that grey2mat() does the job but i am not sure .

Thank you.

Answer 1

[Image Analyst]

What's your definition of normalize? You can use mat2gray(), rescale(), or simply divide by the actual max and multiply by the desired max. It just depends on how you define it. What's your definition? How do you plan on using it?

[Gn Gnk]

I have an assignment that is devided in steps . In the first step i applied top-hat transformation on an image . In the 2nd step i was asked to normalize the top-hat transformed image (just that nothing more ) . And then , in the 3rd step to apply the otsu's method .Just that .That's why i am so confused .

[Gn Gnk]

4th step :Binarize(im2bw) the normalized image with the threshold found in 3rd step . Hope it helps.

[Image Analyst]

The second step is not necessary. Not sure why they wanted you to do it. Otsu's method can work with the original range. Rescaling the image does nothing to help it. It just finds the threshold at a different (higher) threshold than it would have with the original, unscaled image. But anyway, you can scale it like this:

imshow(topHatImage, []);
normalizedImage = mat2gray(topHatImage); % Rescale to 0-1 range.
imshow(normalizedImage, []); % Will look the same since I used [].
threshold = graythresh(normalizedImage)
mask = imbinarize(normalizedImage, threshold); % Apply Otsu method.
imshow(mask); % Display thresholded image.

[Saud Alfalasi]

Hi Image Analyst

May you please look at my questions

https://uk.mathworks.com/matlabcentral/answers/656073-split-rgb-image-into-blocks-24-bit?s_tid=srchtitle