Displaying a png image without the background

debugcn Published at Dev

user3531992

http://sweetclipart.com/multisite/sweetclipart/files/sunglasses_black.png

I have read the png image in MATLAB using [X,map,alpha]=imread('...','png'). Now I want to place this png image on another image. But I want the background color of the read png not to be shown. In the link I want the sunglasses alone to be shown without the 'white' background (Background is another image).

Rafael Monteiro

You can do it like this:

% Image with alpha channel
[glasses, ~, alpha] = imread('http://sweetclipart.com/multisite/sweetclipart/files/sunglasses_black.png');

% OPTIONAL: Let's rescale it (it's very big!)
glasses = imresize(glasses, 0.1);
alpha = imresize(alpha, 0.1);

% An image of a person (let's put the glasses on the person).
person = imread('http://cinemacao.com/wp-content/uploads/2013/12/Scarlett-CAPA-2.jpg');

% Lets make the alpha MxNx3 (so we can combine it with the RGB channels).
alpha = repmat(alpha, [1 1 3]);

% And convert everything from uint8 to double (to avoid precision issues).
glasses = im2double(glasses);
alpha = im2double(alpha);
person = im2double(person);

% Final image

% Let x,y be the top-left coordinates where we'll put the glasses.
x = 440;
y = 450;

% Let's combine the images.
img3 = person;
img3(y:y+size(glasses,1)-1, x:x+size(glasses,2)-1, :) = ...
    glasses .* alpha + ...
    person(y:y+size(glasses,1)-1, x:x+size(glasses,2)-1, :) .* (1 - alpha);

% An display the result.
imshow(img3);

Result: enter image description here