Help how to convert -ve image to +ve image using MATLAB

[susannit]

sir,
I am doing project in NDT. I am inneed of separting the image send me some valuable suggestions I will be very thankful to you.
with thanks
sudharsan.T

 

[medra]

could u explain more what is -ve ,positive image so that i could help u???

 

[Robinenemy]

You can take the absolute value

using I = abs(I);
where I is the image matrix

Regards

Robin

 

[lena]

F(x,y) input image
g(x,y) negative of f(x,y)
g(x,y) = 255- f(x,y);