%Function Name: colorScreen % Inputs (3): - (char) a filename of a foreground im

Question

%Function Name: colorScreen

% Inputs (3): - (char) a filename of a foreground image

%              - (char) a filename of a background image

%              - (double) a vector of length three of RGB values to replace

% Outputs (1): - (uint8) a uint8 array with the colorScreen effect applied

%

% Function Description:

%   Given two images, write a function called "colorScreen" that will

%   replace all pixels in the first image that match a given RGB value with

%   the corresponding pixels in the second image. For example, if the

%   following is called:

%

%             colorScreen('img1.bmp','img2.bmp', [0 255 0]);

%

%   A uint8 array should be returned that should look like 'img1.bmp', but

%   with all of the pure green pixels replaced with the corresponding pixel

%   in 'img2.bmp'.

%

% Notes:

%   - You do not have to use a for loop in this problem. For loops are a

%     very slow and inefficent due to the size of the images that must be

%     looped though. Consider logical indexing instead.

%   - The two input images will always be the same size.

%

% Test Cases:

%   im1 = colorScreen('trex.bmp','ttower.bmp',[0 255 0]);

%   imshow(im1)

%       => should look like soln1.bmp

%   im2 = colorScreen('lookit.bmp','pic.bmp',[237 28 36]);

%   imshow(im2)

%       => should look like soln2.bmp

Explanation / Answer

Save the following as colorScreen.m

function y = colorScreen(img1,img2,inp)

B(:,:,1)=(img2(:,:,1)==inp(1));

B(:,:,2)=(img2(:,:,2)==inp(2));

B(:,:,3)=(img2(:,:,3)==inp(3));

img1(~B)=0;

img2(B)=0;

y=img1+img2;

end

Also save the two images in the present working directory as im1.png and im2.png

Then run the following in the comand window

img1=imread('im1.png');

img2=imread('im2.png');

inp=[0,255,0];

imgo = colorScreen(img1,img2,inp);

imshow(imgo)

Be careful while loading images, load correct images in correct sequence

You can change the input value as you wish to.

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