To Place An Image One Above The Other With The Transparency Provided

Hi,

I have a problem in the following code:

% Frequency Of The First Row
fx1=3.5;fy1=2;
fx2=7;fy2=2;
fx3=10.5;fy3=2;
fx4=14;fy4=2;

% Frequency Of The Second Row
fx5=17.5;fy5=2;
fx6=21;fy6=2;
fx7=24.5;fy7=2;
fx8=28;fy8=2;

% Frequency Of The Third Row
fx9=31.5;fy9=2;
fx10=35;fy10=2;
fx11=38.5;fy11=2;
fx12=42;fy12=2;

% Frequency Of The Fourth Row
fx13=45.5;fy13=2;
fx14=49;fy14=2;
fx15=52.5;fy15=2;
fx16=56;fy16=2;

% Background
[x1,y1]=meshgrid(-1:2/511:1, -1:2/511:1);
z4=sqrt(3).*(2.*(x1.^2+y1.^2)-1); % Defocous

% Aberrations
% z4=sqrt(3).*(2.*(x1.^2+y1.^2)-1); % Defocous
% z5=2.*sqrt(6).*x1.*y1; % Astigmatism at +/-45
% z6=sqrt(6).*(x1.^2-y1.^2); % Astigmatism at 0 or 90
% z7=sqrt(8).*(3.*(x1.^2+y1.^2)-2).*y1; % Primary Y Coma
% z8=sqrt(8).*(3.*(x1.^2+y1.^2)-2).*x1; % Primary X Coma
% z11=sqrt(5).*(6.*(x1.^2+y1.^2).^2-6.*(x1.^2+y1.^2)+1); % Primary Spherical Aberration

% Holograms
a=128;
b=128;

[x,y]=meshgrid(-1:2/127:+1, -1:2/127:+1);
circ=sqrt(x.^2+y.^2)<1;

% Generation Of Holograms
h1=circ.*(cos((x*pi*fx1)+(y*pi*fy1)))>0;
h2=circ.*(cos((x*pi*fx2)+(y*pi*fy2)))>0;
h3=circ.*(cos((x*pi*fx3)+(y*pi*fy3)))>0;
h4=circ.*(cos((x*pi*fx4)+(y*pi*fy4)))>0;

h5=circ.*(cos((x*pi*fx5)+(y*pi*fy5)))>0;
h6=circ.*(cos((x*pi*fx6)+(y*pi*fy6)))>0;
h7=circ.*(cos((x*pi*fx7)+(y*pi*fy7)))>0;
h8=circ.*(cos((x*pi*fx8)+(y*pi*fy8)))>0;

h9=circ.*(cos((x*pi*fx9)+(y*pi*fy9)))>0;
h10=circ.*(cos((x*pi*fx10)+(y*pi*fy10)))>0;
h11=circ.*(cos((x*pi*fx11)+(y*pi*fy11)))>0;
h12=circ.*(cos((x*pi*fx12)+(y*pi*fy12)))>0;

h13=circ.*(cos((x*pi*fx13)+(y*pi*fy13)))>0;
h14=circ.*(cos((x*pi*fx14)+(y*pi*fy14)))>0;
h15=circ.*(cos((x*pi*fx15)+(y*pi*fy15)))>0;
h16=circ.*(cos((x*pi*fx16)+(y*pi*fy16)))>0;

% An Array Of 4x4 Holograms(Concatenation)

%First Row Of Holograms

M(1:a, 1:b) = h1; %M(1, 1)
M(1:a, b+1:b*2) = h2; %M(2, 1)
M(1:a, 2*b+1:b*3) = h3; %M(3, 1) 
M(1:a, 3*b+1:b*4) = h4; %M(4, 1)

% Second Row Of Holograms
M(a+1:a*2, 1:b) = h5;%M(1, 2) 
M(a+1:a*2, b+1:b*2) = h6; %M(2, 2) 
M(a+1:a*2, 2*b+1:b*3) = h7; %M(3, 2) 
M(a+1:a*2, 3*b+1:b*4) = h8; %M(4, 2)

% Third Row Of Holograms
M(2*a+1:a*3, 1:b) = h9; %M(1, 3)
M(2*a+1:a*3, b+1:b*2) = h10; %M(2, 3)
M(2*a+1:a*3, 2*b+1:b*3) = h11; %M(3, 3) 
M(2*a+1:a*3, 3*b+1:b*4) = h12; %M(4, 3) 

% Fourth Row Of Holograms
M(3*a+1:a*4, 1:b) = h13; %M(1, 4)
M(3*a+1:a*4, b+1:b*2) = h14; %M(2, 4)
M(3*a+1:a*4, 2*b+1:b*3) = h15; %M(3, 4)
M(3*a+1:a*4, 3*b+1:b*4) = h16; %M(4, 4)

figure(1)
imagesc(z4); colormap gray; axis image; axis off
title('Background');

figure(2) 
imagesc(M); colormap gray; axis image; axis off
title('Array Of 4x4 Holograms');

************

My problem is that, I want to place figure(2) above figure(1)(i.e. considering it to be the background) in such a way that transparency is allowed. Can anyone please help me out in this regard?

Thanking You!

[Ryan]

I think you need to set the 'AlphaData', here is an example that shows how to set the property.

imagesc should be able to replace imread and I think from the reference page that 'AlphaData' can handle non-binary masks if needed, this example should also help.