Why my input image is displayed as blank image by using the following code?

I got a blank image as both input and output images when i process the matlab codes in the attached file. And there is no error shown in the command window. What is the reason for this and How can i solve this?

Answer 1

[Spencer Chen]

The problem is that your converted your image to a double then applied rgb2gray. When the input is double, rgb2gray is expecting image values between 0 and 1, but your original image has values between 0 to 255 (uint8).

This conversion (to double) step is not necessary to execute rgb2gray.

[sam CP]

When i remove the convert to double(IM=double(IM);) . I got following error

   Error using  .* 
Integers can only be combined with integers of the same class, or scalar doubles.
Error in Untitled2 (line 44)
ccc1=sum(sum(u1.*u1.*IM))/sum(sum(u1.*u1));