MATLAB: Imshow not working when going from unit8 to double

Question

I converted an image from uint8 to double but when I use imshow on the matrix type double, it shows a white box. Why does that happen ?

Answer 1

Most likely because you did not scale the image when you converted the type.

• uint8 images are treated as having values from 0 to 255.
• floating point images are treated as having values from 0 to 1.

So if you convert to double you will need to divide by 255:

Im_double = double(Im_uint8) / 255

or just use im2double, which does this conversion:

Im_double = im2double(Im_uint8)