Embedding watermark in the color image.

I am trying to embed a watermark image into the cover image, but during the reconstructing time the image is not visible.Code is given below and images are attached in the attachment.

RGB1=imread('Marksheet1.png');

RGB1=double(imresize(RGB1, [256 256]));

RGB2=imread('logo1.png');

RGB2=double(imresize(RGB2, [256 256]));

R1 = RGB1(:,:,1);

G1 = RGB1(:,:,2);

B1 = RGB1(:,:,3);

Y1 = 0.299 * R1 + 0.587 * G1 + 0.114 * B1;

U1 = -0.147 * R1 - 0.289 * G1 + 0.437 * B1;

V1 = 0.615 * R1 - 0.515 * G1 - 0.100 * B1;

YUV1=cat(3,Y1,U1,V1);

R2 = RGB2(:,:,1);

G2 = RGB2(:,:,2);

B2 = RGB2(:,:,3);

Y2 = 0.299 * R2 + 0.587 * G2 + 0.114 * B2;

U2 = -0.147 * R2 - 0.289 * G2 + 0.437 * B2;

V2 = 0.615 * R2 - 0.515 * G2 - 0.100 * B2;

YUV2=cat(3,Y2,U2,V2);

imshow(YUV2);

Factor = 8;

Q = zeros(8,8);

for i = 1:8

for j = 1:8

Q(i,j) = 1+(i+j)*Factor;

end

end

Y1_new=f1(Y1,Y2,Q);

U1_new=f1(U1,U2,Q);

V1_new=f1(V1,V2,Q);

R1 = Y1_new + 1.140 * V1_new;

G1 = Y1_new -0.394 * U1_new -0.581 * V1_new;

B1 = Y1_new + 2.028 * U1_new;

RGB_wat = cat(3,R1,G1,B1);

imwrite(uint8(RGB_wat),'RGB_watermarked.png');

a=imread('RGB_watermarked.png');

imshow(uint8(a))

Function f1 is given below

function [output]=f1(data,watermark,Q)

blksize=[8,8];

blk1 = our_blkproc(data,blksize);

blk2 = our_blkproc(watermark,blksize);

dct_img = zeros(8,8,size(blk1,3));

for i=1:size(blk1,3)

dct_img(:,:,i) = dct2(blk1(:,:,i));

end

dct_wat = zeros(8,8,size(blk2,3));

for j=1:size(blk2,3)

dct_wat(:,:,j) = dct2(blk2(:,:,j));

end

img_mat = zeros(8,8,size(blk1,3));

for j=1:size(blk1,3)

img_mat(:,:,j) = blk1(:,:,j)/Q;

end

wat_mat = zeros(8,8,size(blk2,3));

for k=1:size(blk2,3)

wat_mat(:,:,k) = blk2(:,:,k)/Q;

end

t = 0.98;

image_wat = (1-t)*wat_mat + t*img_mat;

image_old = zeros(8,8,size(image_wat,3));

for j=1:size(image_wat,3)

image_old(:,:,j) = (image_wat(:,:,j)*Q);

end

dct_inv = zeros(8,8,size(image_old,3));

for i=1:size(image_old,3)

dct_inv(:,:,i) = idct2(image_old(:,:,i));

end

output = our_blkproc_rev(dct_inv);

[Balkar Singh]

Please guide me. Thanks