Mercurial > octave-dspies
view scripts/image/ntsc2rgb.m @ 15683:806ea52af230
Overhaul m-files in image directory to provide better support for images stored as integers.
* NEWS: Add note about overhaul of image scripts to support integer
classes.
* brighten.m: Add demo.
* colormap.m: Better input validation.
* contrast.m: Re-position window in demo.
* gray2ind.m: Redo docstring. Match variables in docstring to function
prototype. Better input validation. Return integer class outputs as
Matlab does. Add %!tests.
* hsv2rgb.m: Add to docstring. Better input validation. Redo algorithm
to get rido of obsolete matrix-fill methods like kron(). Add %!tests.
* image.m: Redo docstring. Match variables in docstring to function
prototype. Better input validation without using for loops.
* imagesc.m: Redo docstring. Match variables in docstring to function
prototype. Remove DEPRECATEDZOOM functionality. Add demos.
* imfinfo.m: Redo docstring.
* ind2gray.m: Redo docstring. Match variables in docstring to function
prototype. Redo algorithm to directly calculate luminance value rather
than getting it from rgb2ntsc. Add %!tests.
* ind2rgb.m: Redo docstring. Better input validation. Add some %!tests.
* ntsc2rgb.m: Redo docstring. Better input validation. Add %!tests.
* rgb2hsv.m: Better input validation. Add %!tests.
* rgb2ind.m: Better input validation. Code algorithm in cleaner method
for ease of understanding.
* rgb2ntsc.m: Redo docstring: Better input validation. Add some %!tests.
author | Rik <rik@octave.org> |
---|---|
date | Tue, 27 Nov 2012 16:38:13 -0800 |
parents | 1f911333ed3d |
children | b1cd65881592 |
line wrap: on
line source
## Copyright (C) 1994-2012 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 ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {@var{rgb_map} =} ntsc2rgb (@var{yiq_map}) ## @deftypefnx {Function File} {@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 cls = class (yiq); if (! any (isa (yiq, {"uint8", "uint16", "single", "double"}))) error ("ntsc2rgb: invalid data type '%s'", cls); endif ## If we have an image convert it into a color map. if (ismatrix (yiq) && ndims (yiq) == 3) is_image = true; sz = size (yiq); yiq = [yiq(:,:,1)(:), yiq(:,:,2)(:), yiq(:,:,3)(:)]; ## Convert to a double image. if (isinteger (yiq)) cls = class (yiq); low = double (intmin (cls)); high = double (intmax (cls)); yiq = (double (yiq) - low) / (high - low); endif else is_image = false; endif if (! ismatrix (yiq) || columns (yiq) != 3) error ("ntsc2rgb: argument must be a matrix of size Nx3 or NxMx3"); endif ## 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; ## If input was an image, convert it back into one. if (is_image) rgb = reshape (rgb, sz); endif endfunction %!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 %%! ntsc_map = rand (64, 3); %%! assert (rgb2ntsc (ntsc2rgb (ntsc_map)), ntsc_map, 1e-3); % %%!test %%! ntsc_img = rand (64, 64, 3); %%! assert (rgb2ntsc (ntsc2rgb (ntsc_img)), ntsc_img, 1e-3); %% Test input validation %!error ntsc2rgb () %!error ntsc2rgb (1,2) %!error <invalid data type 'cell'> ntsc2rgb ({1}) %!error <must be a matrix of size Nx3 or NxMx3> ntsc2rgb (ones (2,2))