Adding alpha channel to image in matlab .. important question

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I have this code to adding alpha channel to rgb image in matlab but i didnt understand it ,, can any one explain it to me please ? and how can i display the new image and save it for more use ?
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% This image is included with MATLAB
D = imread('C:\Users\Nawar\Desktop\lena.jpg');
image(D); title('RGB image without alpha layer.');
h = size(D,1);
w = size(D,2);
% Create a transparency mask
T = 128*ones(h,w,'uint8');
% The dimensions of our image are h x w x 3 (remember, it's RGB). If
% we wish to add an alpha component, we need to give the image data a 4th
% component.
rgbaData = cat(3,D,T);
% Let's create our new image.
t = Tiff('alpha2.tif','w');
% The photometric interpretation remains RGB, even though we will be
% adding an extra sample.
t.setTag('Photometric',Tiff.Photometric.RGB);
% These three tags define the dimensions of the image in the file.
t.setTag('ImageWidth',w);
t.setTag('ImageLength',h);
t.setTag('BitsPerSample',8);
t.setTag('SamplesPerPixel',4);
% We will make the image consist of 64x64 tiles.
t.setTag('TileWidth',64);
t.setTag('TileLength',64);
t.setTag('PlanarConfiguration',Tiff.PlanarConfiguration.Chunky);
% A photometric interpretation of RGB means that the TIFF file is expecting
% three components. We have to tell it that there will really be four
% components (the alpha layer is the 4th).=
t.setTag('ExtraSamples',Tiff.ExtraSamples.UnassociatedAlpha);
t.write(rgbaData);
t.close();
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Answers (1)

Nawar Alseelawi
Nawar Alseelawi on 6 Aug 2014
please answer me

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