How can I change the background color of the image?

Question

I want to remove/change the background color of an image in Matlab.

Anyone know how to do this?

Here is an example image, I want to remove the green background color.

_{(source: frip.in)}

Answer 1

Simplest answer would be,

c = [70 100 70];
thresh = 50;
A = imread('image.jpg');
B = zeros(size(A));
Ar = A(:,:,1);
Ag = A(:,:,2);
Ab = A(:,:,3);
Br = B(:,:,1);
Bg = B(:,:,2);
Bb = B(:,:,3);
logmap = (Ar > (c(1) - thresh)).*(Ar < (c(1) + thresh)).*...
         (Ag > (c(2) - thresh)).*(Ag < (c(2) + thresh)).*...
         (Ab > (c(3) - thresh)).*(Ab < (c(3) + thresh));
Ar(logmap == 1) = Br(logmap == 1);
Ag(logmap == 1) = Bg(logmap == 1); 
Ab(logmap == 1) = Bb(logmap == 1);
A = cat(3 ,Ar,Ag,Ab);
imshow(A);

You should change c (background color) and thresh (threshold for c) and find the best that fits your background.

You can define B as your new background image. Fr example adding Bb(:,:) = 255;will give you a blue background.

You can even define B as an image.

In order to detect background you could find the color that is most used in the image, but that is not necessarily background I think.