Mercurial > octave
view scripts/image/hsv2rgb.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{rgb_map} =} hsv2rgb (@var{hsv_map}) ## @deftypefnx {} {@var{rgb_img} =} hsv2rgb (@var{hsv_img}) ## Transform a colormap or image from HSV to RGB color space. ## ## 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. ## ## The input can be both a colormap or RGB image. In the case of floating ## point input, values are expected to be on the [0 1] range. In the case ## of hue (azimuth), since the value corresponds to an angle, ## @code{mod (h, 1)} is used. ## ## @example ## @group ## >> hsv2rgb ([0.5 1 1]) ## @result{} ans = 0 1 1 ## ## >> hsv2rgb ([2.5 1 1]) ## @result{} ans = 0 1 1 ## ## >> hsv2rgb ([3.5 1 1]) ## @result{} ans = 0 1 1 ## @end group ## @end example ## ## Output class and size will be the same as input. ## ## @seealso{rgb2hsv, ind2rgb} ## @end deftypefn function rgb = hsv2rgb (hsv) ## Each color value x = (r,g,b) is calculated with ## x = (1-sat)*val+sat*val*f_x(hue) ## where f_x(hue) is a piecewise defined function for ## each color with f_r(hue-2/3) = f_g(hue) = f_b(hue-1/3). if (nargin < 1) print_usage (); endif [hsv, sz, is_im, is_nd] ... = colorspace_conversion_input_check ("hsv2rgb", "HSV", hsv); h = hsv(:,1); s = hsv(:,2); v = hsv(:,3); ## Values of Saturation and Value should also be in the [0 1] range. With ## the exception of hue, values outside this range don't make any sense ## in a cylindrical coordinate system but we must return something for ## Matlab compatibility. User case is when a function returns an hsv ## image just slightly outside the range due to floating point rounding ## errors. ## Prefill rgb map with v*(1-s) rgb = repmat (v .* (1 - s), 1, 3); ## red = hue-2/3 : green = hue : blue = hue-1/3 ## Apply modulo 1 to keep within range [0, 1] hue = mod ([h-2/3 h h-1/3], 1); ## factor s*v -> f f = repmat (s .* v, 1, 3); ## add s*v*hue-function to rgb map rgb += f .* (6 * (hue < 1/6) .* hue + (hue >= 1/6 & hue < 1/2) + (hue >= 1/2 & hue < 2/3) .* (4 - 6 * hue)); rgb = colorspace_conversion_revert (rgb, sz, is_im, is_nd); endfunction ## Test pure colors %!assert (hsv2rgb ([0 0 1]), [1 1 1]) %!assert (hsv2rgb ([1 1 0]), [0 0 0]) %!assert (hsv2rgb ([0 1 1]), [1 0 0]) %!assert (hsv2rgb ([1 1 1]), [1 0 0]) %!assert (hsv2rgb ([1/3 1 1]), [0 1 0]) %!assert (hsv2rgb ([2/3 1 1]), [0 0 1]) %!assert (hsv2rgb ([0 0.5 0.5]), hsv2rgb ([1 0.5 0.5])) ## Not Matlab compatible (Matlab would return [1/2 1/12 1/12]) but ## it's also invalid input. This is, however, the same output as Python ## colorsys module. %!assert (hsv2rgb ([0.5 -0.5 0.5]), [0.75 0.5 0.5]) ## Not Matlab compatible. Matlab returns NaN when hue is outside the ## [0 1] range. But since it's an angle, we can manage it. %!assert (hsv2rgb ([0 0.5 0.5]), hsv2rgb ([2 0.5 0.5])) %!assert (hsv2rgb ([0.5 0.5 0.5]), hsv2rgb ([2.5 0.5 0.5]), eps) %!test %! hsv_map = rand (64, 3); %! assert (rgb2hsv (hsv2rgb (hsv_map)), hsv_map, 1e-6); %!test %! hsv_img = rand (64, 64, 3); %! assert (rgb2hsv (hsv2rgb (hsv_img)), hsv_img, 1e-6); ## support sparse input %!assert (hsv2rgb (sparse ([0 0 1])), sparse ([1 1 1])) %!assert (hsv2rgb (sparse ([0 1 1])), sparse ([1 0 0])) %!assert (hsv2rgb (sparse ([1 1 1])), sparse ([1 0 0])) ## Test input validation %!error <Invalid call> hsv2rgb () %!error <invalid data type> hsv2rgb ({1}) %!error <HSV must be a colormap or HSV image> hsv2rgb (ones (2,2)) ## Test ND input %!test %! hsv = rand (16, 16, 3, 5); %! rgb = zeros (size (hsv)); %! for i = 1:5 %! rgb(:,:,:,i) = hsv2rgb (hsv(:,:,:,i)); %! endfor %! assert (hsv2rgb (hsv), rgb); ## Test output class and size for input images. ## Most of the tests only test for colormap input. %!test %! rgb = hsv2rgb (rand (10, 10, 3)); %! assert (class (rgb), "double"); %! assert (size (rgb), [10 10 3]); %!test %! rgb = hsv2rgb (rand (10, 10, 3, "single")); %! assert (class (rgb), "single"); %! assert (size (rgb), [10 10 3]); %!test %! rgb = (rand (10, 10, 3) * 3 ) - 0.5; # values outside range [0 1] %! rgb = hsv2rgb (rgb); %! assert (class (rgb), "double"); %! assert (size (rgb), [10 10 3]); %!test %! rgb = (rand (10, 10, 3, "single") * 3 ) - 0.5; # values outside range [0 1] %! rgb = hsv2rgb (rgb); %! assert (class (rgb), "single"); %! assert (size (rgb), [10 10 3]); %!test %! rgb = hsv2rgb (randi ([0 255], 10, 10, 3, "uint8")); %! assert (class (rgb), "double"); %! assert (size (rgb), [10 10 3]); %!test %! rgb = hsv2rgb (randi ([0 65535], 10, 10, 3, "uint16")); %! assert (class (rgb), "double"); %! assert (size (rgb), [10 10 3]); %!test %! rgb = hsv2rgb (randi ([-128 127], 10, 10, 3, "int8")); %! assert (class (rgb), "double"); %! assert (size (rgb), [10 10 3]); %!test %! hsv_double = reshape ([2/3 1/3 1 0 1 1 1 0, 1 1 1 1], [2 2 3]); %! hsv_uint8 = reshape (uint8 ([170 85 255 0 255 255 255 0 255 255 255 255]), %! [2 2 3]); %! hsv_int16 = int16 (double (hsv_double * uint16 (65535)) -32768); %! expected = reshape ([0 0 1 1 0 1 0 1 1 0 0 1], [2 2 3]); %! %! assert (hsv2rgb (hsv_double), expected); %! assert (hsv2rgb (hsv_uint8), expected); %! assert (hsv2rgb (hsv_int16), expected); %! assert (hsv2rgb (single (hsv_double)), single (expected), eps (single (2)));