how to convert the pixel values of the image in the range of (0-255) into (0-1)?

Hi i have to convert the image pixel values in the range of (0-255) into (0-1) Is there any function or program available?

Answer 1

[Azzi Abdelmalek]

im1=imread('yourfile');
b=linspace(0,1,255);
im2=arrayfun(@(x) b(x+1),im1)

[Jan]

Again I would definitely avoid the slow array fun, because a lookup table method can be solved directly much faster:

im2 = b(im1 + 1);

[Azzi Abdelmalek]

I've tried this, it works only for mxn array, for jpg (mxnx3) array, it does not work.

[Jan]

Surprising. Then I'd suggest:

im2 = reshape(b(im1(:) + 1), size(im1));

But this looks less attractive, of course. Anyway, it is still faster.

[Azzi Abdelmalek]

Surprising. You are right, I messed up, in fact I've tried b(im) instead of b(im+1), did not even read the error message, thinking it was caused by the matrix dimension. im contains 0 that causes the error. b(im1) worked for a tif image that does not contains a 0

Answer 2

[Jan]

imageUINT8  = randi([0, 255], 640, 480);
imageDOUBLE = image / 255;

See also im2double.

Answer 3

[Image Analyst]

Yes, there is a built-in function. It is called mat2gray().

normalizedImage = mat2gray(grayLevelImage);