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diff scripts/image/rgb2ntsc.m @ 20579:131ce8cfaa80

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Relax input in functions that convert between colorspaces (bug #45456) * scripts/image/hsv2rgb.m, scripts/image/ntsc2rgb.m, scripts/image/rgb2hsv.m, scripts/image/rgb2ntsc.m: remove all input check and leave it up to new private functions handled by all. This adds support for ND images, drops check for values in the [0 1] range, allows integer images, and allows sparse matrices. Also adjust tests and add extra ones. * scripts/image/private/colorspace_conversion_input_check.m, scripts/image/private/colorspace_conversion_revert.m: all of this functions handle input check in the same way. In the same way, they need to prepare the output in the same way based on what preparation was done during input check (transforming image into colormap). So we create two new private functions to avoid repeated code. All code was adapted from hsv2rgb.
author Carnë Draug <carandraug@octave.org>
date Sun, 19 Jul 2015 17:41:21 +0100
parents 7503499a252b
children
line wrap: on
line diff
--- a/scripts/image/rgb2ntsc.m
+++ b/scripts/image/rgb2ntsc.m
@@ -51,33 +51,8 @@
     print_usage ();
   endif
 
-  cls = class (rgb);
-  if (! any (strcmp (cls, {"uint8", "uint16", "single", "double"})))
-    error ("rgb2ntsc: invalid data type '%s'", cls);
-  elseif (isfloat (rgb) && (any (rgb(:) < 0) || any (rgb(:) > 1)))
-    error ("rgb2ntsc: floating point images may only contain values between 0 and 1");
-  endif
-
-  ## If we have an image convert it into a color map.
-  if (isreal (rgb) && ndims (rgb) == 3)
-    is_image = true;
-    sz = size (rgb);
-    rgb = [rgb(:,:,1)(:), rgb(:,:,2)(:), rgb(:,:,3)(:)];
-    ## Convert to a double image.
-    if (isinteger (rgb))
-      low = double (intmin (cls));
-      high = double (intmax (cls));
-      rgb = (double (rgb) - low) / (high - low);
-    elseif (isa (rgb, "single"))
-      rgb = double (rgb);
-    endif
-  else
-    is_image = false;
-  endif
-
-  if (! isreal (rgb) || columns (rgb) != 3 || issparse (rgb))
-    error ("rgb2ntsc: input must be a matrix of size Nx3 or NxMx3");
-  endif
+  [rgb, cls, sz, is_im, is_nd, is_int] ...
+    = colorspace_conversion_input_check ("rgb2ntsc", "RGB", rgb);
 
   ## Reference matrix for transformation from http://en.wikipedia.org/wiki/YIQ
   ## and truncated to 3 significant figures.  Matlab uses this matrix for their
@@ -85,18 +60,11 @@
   trans = [ 0.299,  0.596,  0.211;
             0.587, -0.274, -0.523;
             0.114, -0.322,  0.312 ];
-
-  ## Convert data.
   yiq = rgb * trans;
 
-  ## If input was an image, convert it back into one.
-  if (is_image)
-    yiq = reshape (yiq, sz);
-  endif
-
+  yiq = colorspace_conversion_revert (yiq, cls, sz, is_im, is_nd, is_int);
 endfunction
 
-
 ## Test pure RED, GREEN, BLUE colors
 %!assert (rgb2ntsc ([1 0 0]), [.299  .596  .211])
 %!assert (rgb2ntsc ([0 1 0]), [.587 -.274 -.523])
@@ -114,5 +82,13 @@
 %!error rgb2ntsc ()
 %!error rgb2ntsc (1,2)
 %!error <invalid data type 'cell'> rgb2ntsc ({1})
-%!error <must be a matrix of size Nx3 or NxMx3> rgb2ntsc (ones (2,2))
+%!error <RGB must be a colormap or RGB image> rgb2ntsc (ones (2,2))
 
+## Test ND input
+%!test
+%! rgb = rand (16, 16, 3, 5);
+%! yiq = zeros (size (rgb));
+%! for i = 1:5
+%!   yiq(:,:,:,i) = rgb2ntsc (rgb(:,:,:,i));
+%! endfor
+%! assert (rgb2ntsc (rgb), yiq)