how draw in surf in color blue

i want draw in blue not black in surf and i have this code

rgbPic = im2uint8(rgbPic);
axis([-500 500 -500 500 -500 500]);
xlabel('x');
ylabel('y');
zlabel('z');
xImage = [-300 300; -300 300];   
yImage = [0 0; 0 0];             
zImage = [300 300; -300 -300];

h=surf(xImage,yImage,zImage,...    
  'CData',rgbPic,...
    'FaceColor','texturemap','EdgeColor','none','LineStyle','none','AlphaData',gradient(z));

[Walter Roberson]

What is size(rgbPic), and what does imshow(rgbPic) look like?

[Star Strider]

See also: http://www.mathworks.com/matlabcentral/answers/260779-color-for-surf-3d

[samer mahmoud]

foreground = imfill(foreground,'holes');

bwPicSize = size(foreground);
rgbPic = zeros(bwPicSize(1),bwPicSize(2),3);
rgbPic(foreground==0)=255;
rgbPic(:,:,2) = rgbPic(:,:,1);
rgbPic(:,:,3) = rgbPic(:,:,1);

[samer mahmoud]

walter this the code define all

[Walter Roberson]

Change it to

tmp = zeros(bwPicSize(1),bwPicSize(2));
tmp(foreground==0)=255;
rgbPic = zeros(bwPicSize(1),bwPicSize(2),3);
rgbPic(:,:,3) = tmp;