How to create a checker box image of white and black pixels without using inbuilt function?

Hello All,

I would like to create an image, that has checker box pattern of black and white pixels.

For ex, How do I create an image of dimensions 1280x960, black and white pixels 16x16 each. Please help.

[Walter Roberson]

duplicated by later http://www.mathworks.com/matlabcentral/answers/288038-how-to-create-a-checkerboard-image-without-using-the-inbuilt-function

Answer 1

[John BG]

Deep

this works

sx=1280;sy=960;
bas=16     % length base square side
% assume sx and sy are multiples of base
Lx=(-1).^[1:1:sx/bas];
Ly=(-1).^[1:1:sy/bas];
A=ones(sx,sy);

[Ai Aj]=ind2sub([sx sy],[1:1:sx*sy]);

Ai2=reshape(Ai,[sx sy]);
Aj2=reshape(Aj,[sx sy]);

linex=[1:bas:sx];linex=[linex sx];
liney=[1:bas:sy];liney=[liney sy];

setx=zeros(1,bas);
for k=2:1:(length(linex)-1)
  L1=[linex(k-1):1:(linex(k)-1)]
       setx=[setx;L1];  
end

setx(1,:)=[];
sety=zeros(1,bas);
for k=2:1:length(liney)-1 
  L2=[liney(k-1):1:liney(k)-1];
  sety=[sety;L2];  
end

sety(1,:)=[];
blk=ones(bas,bas);

for k=1:1:sx/bas-1
  for s=1:1:sy/bas-1
          Lx1=blk*Lx(k);
            Ly1=blk*Ly(s);
            L12=Lx1.*Ly1;
          A(setx(k,:),sety(s,:))=A(setx(k,:),sety(s,:)).*L12;
%             A(sety(s,:),setx(k,:))=A(sety(s,:),setx(k,:)).*L12;
  end;  
end;

check you get a chequered boar with

imshow(A)

every 16x16 block has either +1 or -1

Would you please be so kind to mark my answer as accepted answer

thanks in advance

John BG

<mailto:[e-mail] [e-mail]>

Answer 2

[TastyPastry]

myIm = uint8(zeros(rows,cols));
myIm = cat(3,myIm+255,myIm,myIm);
imshow(myIm);

[DGM]

That doesn't actually answer the question. That just creates a solid red image.