Mercurial > octave
view scripts/image/im2double.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) 2007-2024 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{dimg} =} im2double (@var{img}) ## @deftypefnx {} {@var{dimg} =} im2double (@var{img}, "indexed") ## Convert image to double precision. ## ## The conversion of @var{img} to double precision, is dependent on the type of ## input image. The following input classes are supported: ## ## @table @samp ## @item uint8, uint16, and int16 ## The range of values from the class is scaled to the interval [0 1]. ## ## @item logical ## True and false values are assigned a value of 1 and 0 respectively. ## ## @item single ## Values are cast to double. ## ## @item double ## Returns the same image. ## ## @end table ## ## If @var{img} is an indexed image, then the second argument should be the ## string @qcode{"indexed"}. If so, then @var{img} must either be of floating ## point class, or unsigned integer class and it will simply be cast to double. ## If it is an integer class, an offset of +1 is applied. ## ## @seealso{double} ## @end deftypefn function dimg = im2double (img, im_type) if (nargin < 1) print_usage (); endif if (nargin == 1) ## "normal" (non-indexed) images switch (class (img)) case "uint8", dimg = double (img) / 255; case "uint16", dimg = double (img) / 65535; case "int16", dimg = (double (img) + 32768) / 65535; case "single", dimg = double (img); case "logical", dimg = double (img); case "double", dimg = img; otherwise, error ('im2double: IMG is of unsupported class "%s"', class (img)); endswitch else ## indexed images if (! strcmpi (im_type, "indexed")) error ('im2double: second input argument must be the string "indexed"'); elseif (any (isa (img, {"uint8", "uint16"}))) dimg = double (img) + 1; elseif (isfloat (img) || isbool (img)) dimg = double (img); else ## Technically, it could also be of logical class and we do not ## enforce positive integers for floating for Matlab compatibility. ## Still, no need to tell that to the user. error (["im2double: if IMG is indexed, then it must be positive " ... "integer floating points, or unsigned integer class"]); endif endif endfunction %!assert (im2double ([1 2 3]), [1 2 3]) %!assert (im2double (single ([1 2 3])), [1 2 3]) %!assert (im2double (uint8 ([0 127 128 255])), [0 127/255 128/255 1]) %!assert (im2double (uint16 ([0 127 128 65535])), [0 127/65535 128/65535 1]) %!assert (im2double (int16 ([-32768 -32767 -32766 32767])), %! [0 1/65535 2/65535 1]) %!assert (im2double (uint8 ([0 1 255]), "indexed"), [1 2 256]) %!assert (im2double (uint16 ([0 1 2557]), "indexed"), [1 2 2558]) %!assert (im2double ([3 25], "indexed"), [3 25]) %!assert (im2double (single ([3 25]), "indexed"), [3 25]) ## Test for ND input %!function test_im2double_nd (cls, low, high) %! in = rand (2, 4, 2, 3, 2); %! in *= high - low; %! in += low; %! in = cast (in, cls); %! out = zeros (size (in)); %! for n = 1:12 %! out(:,:,n) = im2double (in(:,:,n)); %! endfor %! assert (im2double (in), out); %!endfunction %!test %! test_im2double_nd ("double", 0, 1); %! test_im2double_nd ("single", 0, 1); %! test_im2double_nd ("uint8", 0, 255); %! test_im2double_nd ("uint16", 0, 6535); %! test_im2double_nd ("int16", -32768, 32767); ## Test lack of input check for Matlab compatibility %!assert (im2double ([0 1 2], "indexed"), [0 1 2]) %!assert (im2double ([0 -1 -2], "indexed"), [0 -1 -2]) %!assert (im2double ([0 -1.5 -2], "indexed"), [0 -1.5 -2]) %!assert (im2double ([0 -1.5 -2i], "indexed"), [0 -1.5 -2i]) %!assert (im2double ([false true], "indexed"), [0 1]) %!error <unsigned integer class> im2double (int16 ([17 8]), "indexed") %!error <unsigned integer class> im2double (int16 ([-7 8]), "indexed") %!error <must be the string "indexed"> im2double ([1 2 3], "non-indexed")