Change color of a specific region in eye image [Matlab]

Question

I am trying to change the pupil of the following image:

This is not a featur

Answer 1

Here is a solution for manual selection of the pupil. Basically you select a color with which to want to fill the pupil, then trace a region of interest by hand and the region gets filled. In the example I selected a ridiculously large region but you see the point :)

Here is the code:

clear
clc
close all

A = imread('pupil.jpg');

imshow(A)

%// Create dialog box to choose color to fill.
ListColors = {'red' 'green' 'blue' 'magenta' 'white' 'yellow' 'cyan' 'random'};
[Selection,ok] = listdlg('ListString',ListColors,'PromptString','Choose color','SelectionMode','single');

%//Freehand tool
hHand = imfreehand(gca,'Closed',true);

%// createMask is a method from imfreehand. Image processing toolbox required.
mask = createMask(hHand);

%// Create color mask. You can create your own mask with any 3-element vector.

switch ListColors{Selection}

        case 'red'
            colormask = 255*[1, 0, 0];

        case 'green'
            colormask = 255*[0, 1, 0];

        case 'blue'
            colormask = 255*[0, 0, 1];

        case 'white'
            colormask = 255*[1, 1, 1];

        case 'yellow'
            colormask = 255*[1, 1, 0];

        case 'magenta'
            colormask = 255*[1, 0, 1];

        case 'cyan'
            colormask = 255*[0, 1, 1];

        case 'random'
            colormask = 255*[rand(1), rand(1), rand(1)];
end

% Extract the individual channels.
redChannel = A(:, :, 1);
greenChannel = A(:, :, 2);
blueChannel = A(:, :, 3);

%// Apply mask to the ROI
redChannel(mask) = colormask(1);
greenChannel(mask) =  colormask(2);
blueChannel(mask) = colormask(3);

%// Generate 3 channels final image
A = cat(3, redChannel, greenChannel, blueChannel);

imshow(A)

A few screenshots to show you the output:

1) Select the color (here random)

2) Trace the region

3) Output:

That was fun haha hope that helps!