How can I invert a binary image in MATLAB?

Question

I have a binary image and need to convert all of the black pixels to white pixels and vice versa. Then I need to save the new image to a file. Is there a way to do this without simply looping over every pixel and flipping its value?

Answer 1

If you have a binary image binImage with just zeroes and ones, there are a number of simple ways to invert it:

binImage = ~binImage;
binImage = 1-binImage;
binImage = (binImage == 0);

Then just save the inverted image using the function IMWRITE.

Answer 2

You can use imcomplement matlab function. Say you have a binary image b then,

bc = imcomplement(b); % gives you the inverted version of b
b = imcomplement(bc); % returns it to the original b
imwrite(bc,'c:\...'); % to save the file in disk