Extract all red pixels from image to binary image

Does anybody know of a way to extract all 'red' values [255 0 0] from an image to make a binary image where 1's indicate the locations of red pixels?

I have done this with a loop, but I'm sure there is a much quicker way to do it...

Here's my loop, in case it clears up the objective:

for m = 1:size(img,1)
      for n = 1:size(img,2)
          if img(m,n,1) == 255 && img(m,n,2) == 0 && img(m,n,3) == 0
              HaloRegion_Map(m,n) = 1;
          end
      end
  end

Thanks for your help

Answer 1

[Walter Roberson]

HaloRegion_Map = img(:,:,1) == 255 & img(:,:,2) == 0 && img(:,:,3) == 0;

Answer 2

[Sean de Wolski]

X = uint8(rand(100,100,3)>.5)*255; %sample image with some red
red = all(bsxfun(@eq,X,reshape([255 0 0],[1 1 3])),3); %logical image of red parts

And, for fun, a speed comparison:

X = uint8(rand(500,500,3)>.5)*255;
img = X;
t1 = 0;
t2 = t1;
for ii = 1:100
  tic
  red = all(bsxfun(@eq,X,reshape([255 0 0],[1 1 3])),3);
  t1 = t1+toc;
  tic
  HaloRegion_Map = (img(:,:,1) == 255) & ~img(:,:,2) & ~img(:,:,3);
  t2 = t2+toc;
end
[t1 t2]

ans = 0.3921 0.6233