--- a/NEWS	Tue Jan 16 21:14:22 2018 -0800
+++ b/NEWS	Tue Jan 16 21:23:51 2018 -0800
@@ -212,6 +212,12 @@
       z_test.m
       z_test_2.m
 
+ ** The following image functions have been moved from core Octave to
+    the image package available from Octave Forge.
+
+    ntsc2rgb
+    rgb2ntsc
+
  ** Other new functions added in 4.4:
 
       bounds

--- a/doc/interpreter/image.txi	Tue Jan 16 21:14:22 2018 -0800
+++ b/doc/interpreter/image.txi	Tue Jan 16 21:23:51 2018 -0800
@@ -251,15 +251,12 @@
 @node Color Conversion
 @section Color Conversion
 
-Octave supports conversion from the RGB color system to NTSC and HSV
-and vice versa.
+Octave supports conversion from the RGB color system to the HSV color system
+and vice versa.  It is also possible to convert from a color RGB image to a
+grayscale image. 
 
 @DOCSTRING(rgb2hsv)
 
 @DOCSTRING(hsv2rgb)
 
 @DOCSTRING(rgb2gray)
-
-@DOCSTRING(rgb2ntsc)
-
-@DOCSTRING(ntsc2rgb)

--- a/scripts/image/hsv2rgb.m	Tue Jan 16 21:14:22 2018 -0800
+++ b/scripts/image/hsv2rgb.m	Tue Jan 16 21:23:51 2018 -0800
@@ -48,7 +48,7 @@
 ##
 ## Output class and size will be the same as input.
 ##
-## @seealso{rgb2hsv, ind2rgb, ntsc2rgb}
+## @seealso{rgb2hsv, ind2rgb}
 ## @end deftypefn
 
 ## Author: Kai Habel <kai.habel@gmx.de>

--- a/scripts/image/ind2rgb.m	Tue Jan 16 21:14:22 2018 -0800
+++ b/scripts/image/ind2rgb.m	Tue Jan 16 21:23:51 2018 -0800
@@ -34,7 +34,7 @@
 ## Multi-dimensional indexed images (of size @nospell{MxNx1xK}) are also
 ## supported.
 ##
-## @seealso{rgb2ind, ind2gray, hsv2rgb, ntsc2rgb}
+## @seealso{rgb2ind, ind2gray, hsv2rgb}
 ## @end deftypefn
 
 ## Author: Tony Richardson <arichard@stark.cc.oh.us>

--- a/scripts/image/module.mk	Tue Jan 16 21:14:22 2018 -0800
+++ b/scripts/image/module.mk	Tue Jan 16 21:23:51 2018 -0800
@@ -46,14 +46,12 @@
   %reldir%/iscolormap.m \
   %reldir%/jet.m \
   %reldir%/lines.m \
-  %reldir%/ntsc2rgb.m \
   %reldir%/ocean.m \
   %reldir%/pink.m \
   %reldir%/prism.m \
   %reldir%/rainbow.m \
   %reldir%/rgb2hsv.m \
   %reldir%/rgb2ind.m \
-  %reldir%/rgb2ntsc.m \
   %reldir%/rgb2gray.m \
   %reldir%/rgbplot.m \
   %reldir%/spinmap.m \

--- a/scripts/image/ntsc2rgb.m	Tue Jan 16 21:14:22 2018 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,188 +0,0 @@
-## Copyright (C) 1994-2017 John W. Eaton
-##
-## This file is part of Octave.
-##
-## Octave is free software: you can redistribute it and/or modify it
-## under the terms of the GNU General Public License as published by
-## the Free Software Foundation, either version 3 of the License, or
-## (at your option) any later version.
-##
-## Octave is distributed in the hope that it will be useful, but
-## WITHOUT ANY WARRANTY; without even the implied warranty of
-## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-## GNU General Public License for more details.
-##
-## You should have received a copy of the GNU General Public License
-## along with Octave; see the file COPYING.  If not, see
-## <https://www.gnu.org/licenses/>.
-
-## -*- texinfo -*-
-## @deftypefn  {} {@var{rgb_map} =} ntsc2rgb (@var{yiq_map})
-## @deftypefnx {} {@var{rgb_img} =} ntsc2rgb (@var{yiq_img})
-## Transform a colormap or image from luminance-chrominance (NTSC) space to
-## red-green-blue (RGB) color space.
-##
-## Implementation Note:
-## The conversion matrix is chosen to be the inverse of the matrix used for
-## rgb2ntsc such that
-##
-## @example
-## x == ntsc2rgb (rgb2ntsc (x))
-## @end example
-##
-## @sc{matlab} uses a slightly different matrix where rounding means the
-## equality above does not hold.
-## @seealso{rgb2ntsc, hsv2rgb, ind2rgb}
-## @end deftypefn
-
-## Author: Tony Richardson <arichard@stark.cc.oh.us>
-## Created: July 1994
-## Adapted-By: jwe
-
-function rgb = ntsc2rgb (yiq)
-
-  if (nargin != 1)
-    print_usage ();
-  endif
-
-  ## Unlike other colorspace conversion functions, we do not accept
-  ## integers as valid input.  We check this before
-  ## colorspace_conversion_input_check() which is general and would
-  ## convert integers to double assuming a [0 1] interval range.
-  ## The reason for not supporting integers here is that there's no
-  ## common such conversion.  If we were to support a conversion
-  ## the most reasonable definition would be to convert the YIQ
-  ## from their integer range into the ranges:
-  ##    Y = [ 0      1.106]
-  ##    I = [-0.797  0.587]
-  ##    Q = [-0.322  0.426]
-  ## See https://savannah.gnu.org/patch/?8709#comment11
-  if (! isfloat (yiq))
-    error ("ntsc2rgb: YIQ must be of floating point class");
-  endif
-  [yiq, sz, is_im, is_nd] ...
-    = colorspace_conversion_input_check ("ntsc2rgb", "YIQ", yiq);
-
-  ## Conversion matrix constructed from 'inv (rgb2ntsc matrix)'.
-  ## See programming notes in rgb2ntsc.m.  Note: Matlab matrix for inverse
-  ## is slightly different.  We prefer this matrix so that
-  ## x == ntsc2rgb (rgb2ntsc (x)) rather than maintaining strict compatibility
-  ## with Matlab.
-  trans = [ 1.0,      1.0,      1.0;
-            0.95617, -0.27269, -1.10374;
-            0.62143, -0.64681,  1.70062 ];
-  rgb = yiq * trans;
-  ## Note that if the input is of class single, we also return an image
-  ## of class single.  This is Matlab incompatible by design, since
-  ## Matlab always returning class double, is a Matlab bug (see patch #8709)
-
-  ## truncating / scaling of double rgb values for Matlab compatibility
-  rgb = max (0, rgb);
-  idx = any (rgb > 1, 2);
-  rgb(idx,:) = rgb(idx,:) ./ max (rgb(idx,:), [], 2);
-
-  rgb = colorspace_conversion_revert (rgb, sz, is_im, is_nd);
-
-endfunction
-
-
-%!shared trans
-%! trans = [ 1.0,      1.0,      1.0;
-%!          0.95617, -0.27269, -1.10374;
-%!          0.62143, -0.64681,  1.70062 ];
-
-## Test pure R, G, B colors
-%!assert (ntsc2rgb ([.299  .596  .211]), [1 0 0], 1e-5)
-%!assert (ntsc2rgb ([.587 -.274 -.523]), [0 1 0], 1e-5)
-%!assert (ntsc2rgb ([.114 -.322  .312]), [0 0 1], 1e-5)
-
-%!test
-%! rgb_map = rand (64, 3);
-%! assert (ntsc2rgb (rgb2ntsc (rgb_map)), rgb_map, 1e-3);
-
-%!test
-%! rgb_img = rand (64, 64, 3);
-%! assert (ntsc2rgb (rgb2ntsc (rgb_img)), rgb_img, 1e-3);
-
-## test cropping of rgb output
-%!assert (ntsc2rgb ([1.5 0 0]), [1   1   1])
-
-## Test scaling of output.  After conversion, cut of negative values
-## and scaling of all the others relative to the maximum above 1.
-%!test
-%! ntsc = [0.4229  0.0336  0.7184];
-%! rgb = ntsc * trans;    # [0.9014  -0.0509  1.6075]
-%! rgb(1) /= rgb(3); # scaled based on the maximum
-%! rgb(2) = 0; # cut to 0
-%! rgb(3) = 1; # cut to 1
-%! assert (ntsc2rgb (ntsc), rgb);
-
-## test scaling when conversion has more than one value above 1
-## (check that it does pick the maximum)
-%!test
-%! ntsc = [0.8229  0.3336  0.7184];
-%! rgb = ntsc * trans;    # [1.58831   0.26726   1.67642]
-%! rgb /= rgb(3);
-%! assert (ntsc2rgb (ntsc), rgb);
-
-## check scaling for more than 1 row
-%!test
-%! ntsc = [0.4229  0.0336  0.7184
-%!         0.8229  0.3336  0.7184];
-%! rgb = ntsc * trans;  # [0.9014  -0.0509  1.6075;  1.58831  0.26726  1.67642]
-%! rgb(1,1) /= rgb(1,3);
-%! rgb(1,2) = 0;
-%! rgb(1,3) = 1;
-%! rgb(2,:) /= rgb(2,3);
-%! assert (ntsc2rgb (ntsc), rgb);
-
-## Test input validation
-%!error ntsc2rgb ()
-%!error ntsc2rgb (1,2)
-%!error <YIQ must be of floating point class> ntsc2rgb (uint8 (1))
-%!error <YIQ must be a colormap or YIQ image> ntsc2rgb (ones (2,2))
-%!error <YIQ must be of floating point class> ntsc2rgb (ones ([10 10 3], "uint8"))
-%!error <YIQ must be of floating point class> ntsc2rgb (ones ([10 10 3], "uint16"))
-%!error <YIQ must be of floating point class> ntsc2rgb (ones ([10 10 3], "int16"))
-
-## Test ND input
-%!test
-%! yiq = rand (16, 16, 3, 5);
-%! rgb = zeros (size (yiq));
-%! for i = 1:5
-%!   rgb(:,:,:,i) = ntsc2rgb (yiq(:,:,:,i));
-%! endfor
-%! assert (ntsc2rgb (yiq), rgb);
-
-## Test output class and size for input images.
-## Most of the tests only test for colormap input.
-
-%!test
-%! rgb = ntsc2rgb (rand (10, 10, 3));
-%! assert (class (rgb), "double");
-%! assert (size (rgb), [10 10 3]);
-
-%!test
-%! rgb = ntsc2rgb (rand (10, 10, 3, "single"));
-%! assert (class (rgb), "single");
-%! assert (size (rgb), [10 10 3]);
-
-%!test
-%! ntsc = (rand (10, 10, 3) * 3 ) - 0.5; # values outside range [0 1]
-%! rgb = ntsc2rgb (ntsc);
-%! assert (class (rgb), "double");
-%! assert (size (rgb), [10 10 3]);
-
-%!test
-%! ntsc = (rand (10, 10, 3, "single") * 3 ) - 0.5; # values outside range [0 1]
-%! rgb = ntsc2rgb (ntsc);
-%! assert (class (rgb), "single");
-%! assert (size (rgb), [10 10 3]);
-
-%!test
-%! ntsc_double = reshape ([.299 .587 .114 0 .596 -.274 -.322 0 .211 -.523 .312 0],
-%!                        [2 2 3]);
-%! expected = reshape ([1 0 0 0 0 1 0 0 0 0 1 0], [2 2 3]);
-%!
-%! assert (ntsc2rgb (ntsc_double), expected, 1e-5);
-%! assert (ntsc2rgb (single (ntsc_double)), single (expected), 1e-5);

--- a/scripts/image/rgb2ntsc.m	Tue Jan 16 21:14:22 2018 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,154 +0,0 @@
-## Copyright (C) 1994-2017 John W. Eaton
-##
-## This file is part of Octave.
-##
-## Octave is free software: you can redistribute it and/or modify it
-## under the terms of the GNU General Public License as published by
-## the Free Software Foundation, either version 3 of the License, or
-## (at your option) any later version.
-##
-## Octave is distributed in the hope that it will be useful, but
-## WITHOUT ANY WARRANTY; without even the implied warranty of
-## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-## GNU General Public License for more details.
-##
-## You should have received a copy of the GNU General Public License
-## along with Octave; see the file COPYING.  If not, see
-## <https://www.gnu.org/licenses/>.
-
-## -*- texinfo -*-
-## @deftypefn  {} {@var{yiq_map} =} rgb2ntsc (@var{rgb_map})
-## @deftypefnx {} {@var{yiq_img} =} rgb2ntsc (@var{rgb_img})
-## Transform a colormap or image from red-green-blue (RGB) color space to
-## luminance-chrominance (NTSC) space.  The input may be of class uint8,
-## uint16, single, or double.  The output is of class double.
-##
-## Implementation Note:
-## The reference matrix for the transformation is
-##
-## @example
-## @group
-## /Y\     0.299  0.587  0.114  /R\
-## |I|  =  0.596 -0.274 -0.322  |G|
-## \Q/     0.211 -0.523  0.312  \B/
-## @end group
-## @end example
-##
-## @noindent
-## as documented in @url{http://en.wikipedia.org/wiki/YIQ} and truncated to 3
-## significant figures.  Note: The FCC version of NTSC uses only 2 significant
-## digits and is slightly different.
-## @seealso{ntsc2rgb, rgb2hsv, rgb2ind}
-## @end deftypefn
-
-## Author: Tony Richardson <arichard@stark.cc.oh.us>
-## Created: July 1994
-## Adapted-By: jwe
-
-function yiq = rgb2ntsc (rgb)
-
-  if (nargin != 1)
-    print_usage ();
-  endif
-
-  [rgb, sz, is_im, is_nd] ...
-    = 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
-  ## conversion.
-  trans = [ 0.299,  0.596,  0.211;
-            0.587, -0.274, -0.523;
-            0.114, -0.322,  0.312 ];
-  yiq = rgb * trans;
-  ## Note that if the input is of class single, we also return an image
-  ## of class single.  This is Matlab incompatible by design, since
-  ## Matlab always returning class double, is a Matlab bug (see patch #8709)
-
-  yiq = colorspace_conversion_revert (yiq, sz, is_im, is_nd);
-
-endfunction
-
-
-## Test pure RED, GREEN, BLUE colors
-%!assert (rgb2ntsc ([1 0 0]), [.299  .596  .211])
-%!assert (rgb2ntsc ([0 1 0]), [.587 -.274 -.523])
-%!assert (rgb2ntsc ([0 0 1]), [.114 -.322  .312])
-
-%!test
-%! rgb_map = rand (64, 3);
-%! assert (ntsc2rgb (rgb2ntsc (rgb_map)), rgb_map, 1e-3);
-
-%!test
-%! rgb_img = rand (64, 64, 3);
-%! assert (ntsc2rgb (rgb2ntsc (rgb_img)), rgb_img, 1e-3);
-
-## test tolerance input checking on floats
-%! assert (rgb2ntsc ([1.5 1 1]), [1.149   0.298   0.105], 1e-3);
-
-## Test input validation
-%!error rgb2ntsc ()
-%!error rgb2ntsc (1,2)
-%!error <invalid data type 'cell'> rgb2ntsc ({1})
-%!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);
-
-## Test output class and size for input images.
-## Most of the tests only test for colormap input.
-
-%!test
-%! ntsc = rgb2ntsc (rand (10, 10, 3));
-%! assert (class (ntsc), "double");
-%! assert (size (ntsc), [10 10 3]);
-
-%!test
-%! ntsc = rgb2ntsc (rand (10, 10, 3, "single"));
-%! assert (class (ntsc), "single");
-%! assert (size (ntsc), [10 10 3]);
-
-%!test
-%! rgb = (rand (10, 10, 3) * 3 ) - 0.5; # values outside range [0 1]
-%! ntsc = rgb2ntsc (rgb);
-%! assert (class (ntsc), "double");
-%! assert (size (ntsc), [10 10 3]);
-
-%!test
-%! rgb = (rand (10, 10, 3, "single") * 3 ) - 0.5; # values outside range [0 1]
-%! ntsc = rgb2ntsc (rgb);
-%! assert (class (ntsc), "single");
-%! assert (size (ntsc), [10 10 3]);
-
-%!test
-%! ntsc = rgb2ntsc (randi ([0 255], 10, 10, 3, "uint8"));
-%! assert (class (ntsc), "double");
-%! assert (size (ntsc), [10 10 3]);
-
-%!test
-%! ntsc = rgb2ntsc (randi ([0 65535], 10, 10, 3, "uint16"));
-%! assert (class (ntsc), "double");
-%! assert (size (ntsc), [10 10 3]);
-
-%!test
-%! ntsc = rgb2ntsc (randi ([-128 127], 10, 10, 3, "int8"));
-%! assert (class (ntsc), "double");
-%! assert (size (ntsc), [10 10 3]);
-
-%!test
-%! rgb_double = reshape ([1 0 0 0 0 1 0 0 0 0 1 0], [2 2 3]);
-%! rgb_uint8  = reshape (uint8 ([255 0 0 0 0 255 0 0 0 0 255 0]),
-%!                       [2 2 3]);
-%! rgb_int16 = int16 (double (rgb_double * uint16 (65535)) -32768);
-%! expected = reshape ([.299 .587 .114 0 .596 -.274 -.322 0 .211 -.523 .312 0],
-%!                     [2 2 3]);
-%!
-%! assert (rgb2ntsc (rgb_double), expected);
-%! assert (rgb2ntsc (rgb_uint8), expected);
-%! assert (rgb2ntsc (single (rgb_double)), single (expected));