--- a/scripts/image/rgb2hsv.m	Tue Apr 23 03:40:25 2002 +0000
+++ b/scripts/image/rgb2hsv.m	Wed Apr 24 04:56:11 2002 +0000
@@ -43,48 +43,40 @@
     error ("rgb2hsv: argument must be a matrix of size n x 3");
   endif
 
-  # get saturation and value
-  v = max (rgb');
-  s = (v' > 0) .* (1 .- min (rgb') ./ v)';
-
-  # if v==0 set s to 0 too
-  s(isnan (s)) = 0;
+  ## get the max and min
+  s = min (rgb')';
+  v = max (rgb')';
 
-  # subtract minimum and divide trough maximum
-  # to get the bright and saturated colors
-  sc = (rgb - kron ([1, 1, 1], min (rgb')'));
-  sv = sc ./ kron([1, 1, 1], max (sc')');
-
-  # if r=g=b (gray value) set hue to 0
-  sv(isnan (sv)) = 0;
-
-  # hue=f(color) must be splitted into 6 parts 
-  # 2 for each color
+  ## set hue to zero for undefined values (gray has no hue)
+  h = zeros (size (v));
+  notgray = (s != v);
+    
+  ## blue hue
+  idx = (v == rgb(:,3) & notgray);
+  if (any (idx))
+    h(idx) = 2/3 + 1/6 * (rgb(idx,1) - rgb(idx,2)) ./ (v(idx) - s(idx));
+  endif
 
-  # h1(green)
-  tmp = (sv(:, 1) == 1 & sv(:,3) == 0) .* (1/6 * sv(:,2) + eps);
-  # avoid problems with h2(red) since hue(0)==hue(1)
-  h = (tmp < 1/6) .* tmp; 
-  # h2(green)
-  h = h + ((h == 0) & sv(:,1) == 0 & sv(:,3) == 1) \
-      .* (-1/6 * sv(:,2) + 2/3 + eps);
-
-  # h1(red)
-  h = h + ((h == 0) & sv(:,2) == 1 & sv(:,3) == 0) \
-      .* (-1/6 * sv(:,1) + 1/3 + eps);
+  ## green hue
+  idx = (v == rgb(:,2) & notgray);
+  if (any (idx))
+    h(idx) = 1/3 + 1/6 * (rgb(idx,3) - rgb(idx,1)) ./ (v(idx) - s(idx));
+  endif
 
-  # h2(red)
-  h = h + ((h == 0) & sv(:,2) == 0 & sv(:,3) == 1) \
-      .* (1/6 * sv(:,1) + 2/3 + eps);
+  ## red hue
+  idx = (v == rgb(:,1) & notgray);
+  if (any (idx))
+    h(idx) =       1/6 * (rgb(idx,2) - rgb(idx,3)) ./ (v(idx) - s(idx));
+  endif
 
-  # h1(blue)
-  h = h + ((h == 0) & sv(:,1) == 1 & sv(:,2) == 0) \
-      .* (-1/6 * sv(:,3) + 1 + eps);
+  ## correct for negative red
+  idx = (h < 0);
+  h(idx) = 1+h(idx);
 
-  # h2(blue)
-  h = h + ((h == 0) & sv(:,1) == 0 & sv(:,2) == 1) \
-      .* (1/6 * sv(:,3) + 1/3);
+  ## set the saturation
+  s(! notgray) = 0;
+  s(notgray) = 1 - s(notgray) ./ v(notgray);
 
-  hsval = [h, s, v'];
+  hsval = [h, s, v];
 
 endfunction