Hi Balkar Singh,
Alpha blending method is used to watermark an image here
Watermarked_Image = Original_Image *alpha + (1-alpha)*watermark
Where alpha is the transparency parameter.
The following code demostrates this,
watermark = imread('saturn.png');
%Resize the watermark according to the area
modified = imresize(watermark,[64,64],'bilinear');
disp(size(modified));
original_image = imread('Marksheet1.png');
temp = zeros(size(original_image),'uint8');
[rows, cols, depth] = size(modified);
%Co-ordinnates to place the watermark
X = 21;
Y = 441;
temp(X:X+rows-1,Y:Y+cols-1,:) = modified;
temp(301:364,101:164,:) = modified;
temp(301:364,401:464,:) = modified;
alpha = 0.8;
watermarked_image = alpha * original_image + (1-alpha)*temp;
imshow(watermarked_image);
