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view scripts/image/rgb2ind.m @ 27918:b442ec6dda5c
use centralized file for copyright info for individual contributors
* COPYRIGHT.md: New file.
* In most other files, use "Copyright (C) YYYY-YYYY The Octave Project
Developers" instead of tracking individual names in separate source
files. The motivation is to reduce the effort required to update the
notices each year.
Until now, the Octave source files contained copyright notices that
list individual contributors. I adopted these file-scope copyright
notices because that is what everyone was doing 30 years ago in the
days before distributed version control systems. But now, with many
contributors and modern version control systems, having these
file-scope copyright notices causes trouble when we update copyright
years or refactor code.
Over time, the file-scope copyright notices may become outdated as new
contributions are made or code is moved from one file to
another. Sometimes people contribute significant patches but do not
add a line claiming copyright. Other times, people add a copyright
notice for their contribution but then a later refactoring moves part
or all of their contribution to another file and the notice is not
moved with the code. As a practical matter, moving such notices is
difficult -- determining what parts are due to a particular
contributor requires a time-consuming search through the project
history. Even managing the yearly update of copyright years is
problematic. We have some contributors who are no longer
living. Should we update the copyright dates for their contributions
when we release new versions? Probably not, but we do still want to
claim copyright for the project as a whole.
To minimize the difficulty of maintaining the copyright notices, I
would like to change Octave's sources to use what is described here:
https://softwarefreedom.org/resources/2012/ManagingCopyrightInformation.html
in the section "Maintaining centralized copyright notices":
The centralized notice approach consolidates all copyright
notices in a single location, usually a top-level file.
This file should contain all of the copyright notices
provided project contributors, unless the contribution was
clearly insignificant. It may also credit -- without a copyright
notice -- anyone who helped with the project but did not
contribute code or other copyrighted material.
This approach captures less information about contributions
within individual files, recognizing that the DVCS is better
equipped to record those details. As we mentioned before, it
does have one disadvantage as compared to the file-scope
approach: if a single file is separated from the distribution,
the recipient won't see the contributors' copyright notices.
But this can be easily remedied by including a single
copyright notice in each file's header, pointing to the
top-level file:
Copyright YYYY-YYYY The Octave Project Developers
See the COPYRIGHT file at the top-level directory
of this distribution or at https://octave.org/COPYRIGHT.html.
followed by the usual GPL copyright statement.
For more background, see the discussion here:
https://lists.gnu.org/archive/html/octave-maintainers/2020-01/msg00009.html
Most files in the following directories have been skipped intentinally
in this changeset:
doc
libgui/qterminal
liboctave/external
m4
author | John W. Eaton <jwe@octave.org> |
---|---|
date | Mon, 06 Jan 2020 15:38:17 -0500 |
parents | 00f796120a6d |
children | 1891570abac8 |
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## Copyright (C) 1994-2019 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this distribution ## or <https://octave.org/COPYRIGHT.html/>. ## ## ## 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{x}, @var{map}] =} rgb2ind (@var{rgb}) ## @deftypefnx {} {[@var{x}, @var{map}] =} rgb2ind (@var{R}, @var{G}, @var{B}) ## Convert an image in red-green-blue (RGB) color space to an indexed image. ## ## The input image @var{rgb} can be specified as a single matrix of size ## @nospell{MxNx3}, or as three separate variables, @var{R}, @var{G}, and ## @var{B}, its three color channels, red, green, and blue. ## ## It outputs an indexed image @var{x} and a colormap @var{map} to interpret ## an image exactly the same as the input. No dithering or other form of color ## quantization is performed. The output class of the indexed image @var{x} ## can be uint8, uint16 or double, whichever is required to specify the ## number of unique colors in the image (which will be equal to the number ## of rows in @var{map}) in order. ## ## Multi-dimensional indexed images (of size @nospell{MxNx3xK}) are also ## supported, both via a single input (@var{rgb}) or its three color channels ## as separate variables. ## ## @seealso{ind2rgb, rgb2hsv, rgb2gray} ## @end deftypefn ## FIXME: This function has a very different syntax than the Matlab ## one of the same name. ## Octave function does not support N, MAP, DITHER, or TOL arguments. ## Author: Tony Richardson <arichard@stark.cc.oh.us> ## Created: July 1994 ## Adapted-By: jwe function [x, map] = rgb2ind (R, G, B) if (nargin != 1 && nargin != 3) print_usage (); endif if (nargin == 1) rgb = R; if (ndims (rgb) > 4 || size (rgb, 3) != 3) error ("rgb2ind: argument is not an RGB image"); else R = rgb(:,:,1,:); G = rgb(:,:,2,:); B = rgb(:,:,3,:); endif elseif (! size_equal (R, G, B)) error ("rgb2ind: R, G, and B must have the same size"); endif x = reshape (1:numel (R), size (R)); map = unique ([R(:) G(:) B(:)], "rows"); [~, x] = ismember ([R(:) G(:) B(:)], map, "rows"); x = reshape (x, size (R)); ## a colormap is of class double and values between 0 and 1 switch (class (R)) case {"single", "double", "logical"} ## do nothing, return the same case {"uint8", "uint16"} map = double (map) / double (intmax (R)); case "int16" map = (double (im) + 32768) / 65535; otherwise error ("rgb2ind: unsupported image class %s", im_class); endswitch ## we convert to the smallest class necessary to encode the image. Matlab ## documentation does not mention what it does when uint16 is not enough... ## When an indexed image is of integer class, there's a -1 offset to the ## colormap, hence the adjustment if (rows (map) < 256) x = uint8 (x - 1); elseif (rows (map) < 65536) x = uint16 (x - 1); else ## leave it as double endif endfunction ## Test input validation %!error rgb2ind () %!error rgb2ind (1,2,3,4,5,6,7) %!error <RGB> rgb2ind (rand (10, 10, 4)) ## FIXME: the following tests simply make sure that rgb2ind and ind2rgb ## reverse each other. We should have better tests for this. ## Typical usage %!test %! rgb = rand (10, 10, 3); %! [ind, map] = rgb2ind (rgb); %! assert (ind2rgb (ind, map), rgb); %! %! ## test specifying the RGB channels separated %! [ind, map] = rgb2ind (rgb(:,:,1), rgb(:,:,2), rgb(:,:,3)); %! assert (ind2rgb (ind, map), rgb); ## Test N-dimensional images %!test %! rgb = rand (10, 10, 3, 10); %! [ind, map] = rgb2ind (rgb); %! assert (ind2rgb (ind, map), rgb); %! [ind, map] = rgb2ind (rgb(:,:,1,:), rgb(:,:,2,:), rgb(:,:,3,:)); %! assert (ind2rgb (ind, map), rgb); ## Test output class %!test %! ## this should have more than 65536 unique colors %! rgb = rand (1000, 1000, 3); %! [ind, map] = rgb2ind (rgb); %! assert (class (ind), "double"); %! assert (class (map), "double"); %! %! ## and this should have between 255 and 65536 unique colors %! rgb = rand (20, 20, 3); %! [ind, map] = rgb2ind (rgb); %! assert (class (ind), "uint16"); %! assert (class (map), "double"); %! %! ## and this certainly less than 256 unique colors %! rgb = rand (10, 10, 3); %! [ind, map] = rgb2ind (rgb); %! assert (class (ind), "uint8"); %! assert (class (map), "double");