Mercurial > octave-nkf
view scripts/image/rgb2hsv.m @ 15714:b1cd65881592
Clean up scripts in image directory.
Use Octave coding conventions. Redo docstrings. Add %!tests.
* brighten.m: Put input validation first. Use iscolormap to simplify
input checking.
* cmunique.m: Use faster method of validating input class.
* colormap.m: Tweak docstring. Improve input validation.
* contrast.m: Tweak docstring. Use cmap instead of map as variable
name for clarity.
* gray2ind.m: Wrap long lines. Use faster method of validating input class.
Delete unreachable code for n>65536.
* hsv2rgb.m: Use faster method of validating input class.
* imwrite.m: Tweak FIXME notes.
* ind2gray.m: Use correct caller name for ind2x. Update %!tests
with new 2-input calling convention.
* ind2rgb.m: Tweak docstring. Update %!tests with new 2-input
calling convention.
* iscolormap.m: Tweak docstring. Re-order validation tests.
* ntsc2rgb.m: Use faster method of validating input class. Better input
validation. Add %!tests.
* private/ind2x.m: Use more descriptive variable names.
* rgb2hsv.m: Tweak docstring. Use faster method of validating input class.
* rgb2ind.m: Tweak docstring. Wrap long lines.
* rgb2ntsc.m: Use faster method of validating input class. Improve input
validation. Add %!tests.
* rgbplot.m: Match variable names in docstring to those in function
prototype.
author | Rik <rik@octave.org> |
---|---|
date | Sun, 02 Dec 2012 10:02:57 -0800 |
parents | 806ea52af230 |
children | d63878346099 |
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## Copyright (C) 1999-2012 Kai Habel ## ## 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{hsv_map} =} rgb2hsv (@var{rgb}) ## @deftypefnx {Function File} {@var{hsv_map} =} rgb2hsv (@var{rgb}) ## Transform a colormap or image from red-green-blue (RGB) space to ## hue-saturation-value (HSV) space. ## ## A color in the RGB space consists of red, green, and blue intensities. ## ## A color in HSV space is represented by hue, saturation, and value ## (brightness) levels. Value gives the amount of light in the color. Hue ## describes the dominant wavelength. Saturation is the amount of hue mixed ## into the color. ## @seealso{hsv2rgb, rgb2ind, rgb2ntsc} ## @end deftypefn ## Author: Kai Habel <kai.habel@gmx.de> ## Adapted-by: jwe function hsv_map = rgb2hsv (rgb) if (nargin != 1) print_usage (); endif cls = class (rgb); if (! any (strcmp (cls, {"uint8", "uint16", "single", "double"}))) error ("rgb2hsv: invalid data type '%s'", cls); elseif (isfloat (rgb) && (any (rgb(:) < 0) || any (rgb(:) > 1))) error ("rgb2hsv: 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); endif else is_image = false; endif if (! ismatrix (rgb) || columns (rgb) != 3 || issparse (rgb)) error ("rgb2hsv: input must be a matrix of size Nx3 or MxNx3"); endif ## get the max and min for each row s = min (rgb, [], 2); v = max (rgb, [], 2); ## set hue to zero for undefined values (gray has no hue) h = zeros (rows (rgb), 1); 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 ## 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 ## 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 h(h < 0) += 1; # correct for negative red ## set the saturation s(! notgray) = 0; s(notgray) = 1 - s(notgray) ./ v(notgray); hsv_map = [h, s, v]; ## FIXME: rgb2hsv does not preserve class of image. ## Should it also convert back to uint8, uint16 for integer images? ## If input was an image, convert it back into one. if (is_image) hsv_map = reshape (hsv_map, sz); endif endfunction %% Test pure colors and gray %!assert (rgb2hsv ([1 0 0]), [0 1 1]) %!assert (rgb2hsv ([0 1 0]), [1/3 1 1]) %!assert (rgb2hsv ([0 0 1]), [2/3 1 1]) %!assert (rgb2hsv ([0.5 0.5 0.5]), [0 0 0.5]) %!test %! rgb_map = rand (64, 3); %! assert (hsv2rgb (rgb2hsv (rgb_map)), rgb_map, 1e-6); %!test %! rgb_img = rand (64, 64, 3); %! assert (hsv2rgb (rgb2hsv (rgb_img)), rgb_img, 1e-6); %% Test input validation %!error rgb2hsv () %!error rgb2hsv (1,2) %!error <invalid data type 'cell'> rgb2hsv ({1}) %!error <must be a matrix of size Nx3> rgb2hsv (ones (2,2))