Mercurial > octave
view scripts/image/rgb2hsv.m @ 33529:4aec1230dd8f bytecode-interpreter tip
maint: Merge default to bytecode-interpreter
author | Arun Giridhar <arungiridhar@gmail.com> |
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date | Sat, 04 May 2024 08:31:05 -0400 |
parents | 2e484f9f1f18 |
children |
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######################################################################## ## ## Copyright (C) 1999-2024 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## 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{hsv_map} =} rgb2hsv (@var{rgb_map}) ## @deftypefnx {} {@var{hsv_img} =} rgb2hsv (@var{rgb_img}) ## Transform a colormap or image from RGB to HSV color 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 in a cylindrical coordinate system. Hue is the ## azimuth and describes the dominant color. Saturation is the radial ## distance and gives the amount of hue mixed into the color. Value is ## the height and is the amount of light in the color. ## ## Output class and size will be the same as input. ## ## @seealso{hsv2rgb, rgb2ind, rgb2gray} ## @end deftypefn function hsv = rgb2hsv (rgb) if (nargin < 1) print_usage (); endif [rgb, sz, is_im, is_nd] ... = colorspace_conversion_input_check ("rgb2hsv", "RGB", rgb); ## 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 = [h, s, v]; hsv = colorspace_conversion_revert (hsv, sz, is_im, is_nd); 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 ([1 1 0]), [1/6 1 1]) %!assert (rgb2hsv ([0 1 1]), [1/2 1 1]) %!assert (rgb2hsv ([1 0 1]), [5/6 1 1]) %!assert (rgb2hsv ([0.5 0.5 0.5]), [0 0 0.5]) ## Test tolarant input checking on floats %!assert (rgb2hsv ([1.5 1 1]), [0 1/3 1.5], eps) %!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); ## support sparse input %!assert (rgb2hsv (sparse ([0 0 1])), sparse ([2/3 1 1])) %!assert (rgb2hsv (sparse ([0 1 1])), sparse ([1/2 1 1])) %!assert (rgb2hsv (sparse ([1 1 1])), sparse ([0 0 1])) ## Test input validation %!error <Invalid call> rgb2hsv () %!error <invalid data type 'cell'> rgb2hsv ({1}) %!error <RGB must be a colormap or RGB image> rgb2hsv (ones (2,2)) ## Test ND input %!test %! rgb = rand (16, 16, 3, 5); %! hsv = zeros (size (rgb)); %! for i = 1:5 %! hsv(:,:,:,i) = rgb2hsv (rgb(:,:,:,i)); %! endfor %! assert (rgb2hsv (rgb), hsv); ## Test output class and size for input images. ## Most of the tests only test for colormap input. %!test %! hsv = rgb2hsv (rand (10, 10, 3)); %! assert (class (hsv), "double"); %! assert (size (hsv), [10 10 3]); %!test %! hsv = rgb2hsv (rand (10, 10, 3, "single")); %! assert (class (hsv), "single"); %! assert (size (hsv), [10 10 3]); %!test %! rgb = (rand (10, 10, 3) * 3 ) - 0.5; # values outside range [0 1] %! hsv = rgb2hsv (rgb); %! assert (class (hsv), "double"); %! assert (size (hsv), [10 10 3]); %!test %! rgb = (rand (10, 10, 3, "single") * 3 ) - 0.5; # values outside range [0 1] %! hsv = rgb2hsv (rgb); %! assert (class (hsv), "single"); %! assert (size (hsv), [10 10 3]); %!test %! hsv = rgb2hsv (randi ([0 255], 10, 10, 3, "uint8")); %! assert (class (hsv), "double"); %! assert (size (hsv), [10 10 3]); %!test %! hsv = rgb2hsv (randi ([0 65535], 10, 10, 3, "uint16")); %! assert (class (hsv), "double"); %! assert (size (hsv), [10 10 3]); %!test %! hsv = rgb2hsv (randi ([-128 127], 10, 10, 3, "int8")); %! assert (class (hsv), "double"); %! assert (size (hsv), [10 10 3]); %!test %! rgb_double = reshape ([1 0 1 .5 1 1 0 .5 0 1 1 .5], [2 2 3]); %! rgb_uint8 = reshape (uint8 ([255 0 255 128 255 255 0 128 0 255 255 128]), %! [2 2 3]); %! rgb_int16 = int16 (double (rgb_double * uint16 (65535)) -32768); %! expected = reshape ([1/6 1/2 5/6 0 1 1 1 0 1 1 1 .5], [2 2 3]); %! %! assert (rgb2hsv (rgb_double), expected); %! assert (rgb2hsv (rgb_uint8), expected, 0.005); %! assert (rgb2hsv (single (rgb_double)), single (expected));