Rescale a grayscale image

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Ana Gabriela Guedes
Ana Gabriela Guedes on 1 Nov 2021
Hi!
I have this input image: CT-MONO2-16-ankle.dcm and I need to read this dicom file and rescale the grayscale image by mapping the full range of its content intensity to the scale of the corresponding image data type (this is what is written in the assignment I have to do).
Can someone please help me? I don't understand what am I supposed to do in here or how since the image is already in grayscale.
Thank you!

Accepted Answer

DGM
DGM on 1 Nov 2021
Consider the following image. The image content does not span the extent of the allowable range.
A = dicomread('CT-MONO2-16-ankle.dcm');
getrangefromclass(A) % standard data range for the class of A
ans = 1×2
-32768 32767
[min(A(:)) max(A(:))] % show the actual range of the data
ans = 1×2
32 4080
Normalize it and then scale/cast it to whatever the intended working image class is supposed to be. If you assume that it should remain int16:
B = im2int16(mat2gray(A)); % normalize, cast and scale
[min(B(:)) max(B(:))] % show the actual data range
ans = 1×2
-32768 32767
Or if you want uint8:
C = im2uint8(mat2gray(A)); % normalize, cast and scale
[min(C(:)) max(C(:))] % show the actual data range
ans = 1×2
0 255
Or if you just want double:
D = mat2gray(A); % normalize
[min(D(:)) max(D(:))] % show the actual data range
ans = 1×2
0 1
  1 Comment
Ana Gabriela Guedes
Ana Gabriela Guedes on 1 Nov 2021
Thank you so much!! It worked for what I needed

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