How do I invert a grayscale image and convert it to a binary image?

Question

I want to create an image like this: From an image like this:

Answer 1

It depends on what type your input matrix is.

If it is a logical matrix you can simply use

invImg = ~img;

If you have scalar values in the range of 0 to n use

invImg = n - img;

Edit:

If you want a black and white image try the following (perhaps you need to play with the level paramter):

invImg = ~im2bw(img, 0.5);