how can save gray scale image without loss information ?

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K. Taieb
K. Taieb 2020-5-20
回答： Image Analyst 2020-5-21
Hello,
I converted a matrix to a grayscale image.
I saved the image with imwrite
I read the image with imread
The data obtained (uint8) between 0 and 255. in order to convert them to double (0,1) I used im2double.
The result obtained (I3) is a little different to the initial data (I). Is it possible to avoid this error and obtain the same result (I3 = I)?
Thank you
A =[0 200 400 600; 800 1000 1200 1400;1600 1800 2000 2200];
Amin=min(min(A));
Amax=max(max(A));
I=mat2gray(A,[Amin Amax]);
imwrite(I,'NewFile.png')
I2=imread('NewFile.png');
I3= im2double(I2);
isequal(I,I3)

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darova
darova 2020-5-20
Try this
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Image Analyst
Image Analyst 2020-5-21
I never use im2double(). If it's double, just use it as double. If it's integer and you want double, just use double(). If you want to store as double, use save() and save it to a .mat file. If you want an integer file so you have nice little icons in File Explorer, cast to uint16 or uint8. If the number is beyond those ranges, you can use rescale() or mat2gray() to scale the data before casting to integer.

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