how to solve the problem of matrices dimension must agree

Hello, i need an assistance on how to add two variables/matrices in my code below. one is w_LL(256x256x3 double) and the other is Ir_LL(256x256 double).Attached is the code.Thank you.

CODE------------------

t=0.10;

newhost_LLr =Ir_LL+(t*w_LL);

r2=idwt2(newhost_LLr,Ir_LH,Ir_HL,Ir_HH,'haar');

figure(2);imshow(uint8(r2));title('Watermarked image of r component');

newhost_LLg =Ig_LL+(t*w_LL);

g2=idwt2(newhost_LLg,Ig_LH,Ig_HL,Ig_HH,'haar');

figure(2);imshow(uint8(g2));title('Watermarked image of g component');

newhost_LLb =Ib_LL+(t*w_LL);

b2=idwt2(newhost_LLb,Ib_LH,Ib_HL,Ib_HH,'haar');

figure(2);imshow(uint8(r2));title('Watermarked image of g component');

%imwrite(uint8(rgb2),'images/Watermarked33.jpg');

Answer 1

[Image Analyst]

Make it an RGB image also

rgbImage = cat(3, Ir_LL, Ir_LL, Ir_LL);
newhost_LLr = rgbImage + (t * w_LL);

[OLUFEMI SONEYE]

Image Analyst, thanks for your response but error still comes up at the point of finding the idwt. Please, assist me on this.Thanks.

[OLUFEMI SONEYE]

This is the modified version of the code after your contribution---------------------

t=0.10;

R = cat(3, Ir_LL, Ir_LL, Ir_LL);

newhost_LLr = R + (t * w_LL);

%newhost_LLr =Ir_LL+(t*w_LL);

r2=idwt2(newhost_LLr,Ir_LH,Ir_HL,Ir_HH,'haar');

figure(2);imshow(uint8(r2));title('Watermarked image of r component');

G = cat(3, Ig_LL, Ig_LL, Ig_LL);

newhost_LLr = G + (t * w_LL);

%newhost_LLg =Ig_LL+(t*w_LL);

g2=idwt2(newhost_LLg,Ig_LH,Ig_HL,Ig_HH,'haar');

figure(2);imshow(uint8(g2));title('Watermarked image of g component');

B = cat(3, Ib_LL, Ib_LL, Ib_LL);

newhost_LLr = B + (t * w_LL);

%newhost_LLb =Ib_LL+(t*w_LL);

b2=idwt2(newhost_LLb,Ib_LH,Ib_HL,Ib_HH,'haar');

figure(2);imshow(uint8(b2));title('Watermarked image of g component');

%imwrite(uint8(rgb2),'images/Watermarked33.jpg');

It popped error on line 4 at the point of finding the idwt. I will appreciate your more contributions. Thank you.

[Image Analyst]

Sorry - I don't have the Wavelets toolbox so I can't help you on the idwt2() function. Make sure what kind of image (color or gray scale) you're supposed to pass it.