Mercurial > hg > octave-image
changeset 552:30f0a2a06f02
im2uint8: matlab compatibility and support for indexed images
author | carandraug |
---|---|
date | Wed, 11 Apr 2012 18:23:09 +0000 |
parents | 26f74317f196 |
children | be52435a5794 |
files | NEWS inst/im2uint16.m inst/im2uint8.m |
diffstat | 3 files changed, 73 insertions(+), 36 deletions(-) [+] |
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--- a/inst/im2uint16.m +++ b/inst/im2uint16.m @@ -45,7 +45,7 @@ ## do nothing, return the same case {"single", "double"} if (indexed) - imax = max( im(:)); + imax = max (im(:)); if ( imax > intmax ("uint16")) error ("Too many colors '%d' for an indexed uint16 image", imax); endif
--- a/inst/im2uint8.m +++ b/inst/im2uint8.m @@ -1,47 +1,83 @@ -## Copyright (C) 2007 Søren Hauberg -## -## This program 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 2, or (at your option) -## any later version. -## -## This program 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 this file. If not, see <http://www.gnu.org/licenses/>. +## Copyright (C) 2007 Søren Hauberg <soren@hauberg.org> +## Copyright (C) 2012 Carnë Draug <carandraug+dev@gmail.com> +## +## This program 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. +## +## This program 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 +## this program; if not, see <http://www.gnu.org/licenses/>. ## -*- texinfo -*- -## @deftypefn {Function File} @var{im2} = im2uint8(@var{im1}) -## Converts the input image to an image of class uint8. +## @deftypefn {Function File} @var{im2} = im2uint8 (@var{im1}) +## @deftypefnx {Function File} @var{im2} = im2uint8 (@var{im1}, "indexed") +## Convert input image @var{im1} to uint16 precision. +## +## The following images type are supported: double, single, uint8, uint16, int16, +## binary (logical), indexed. If @var{im1} is an indexed images, the second +## argument must be a string with the value `indexed'. ## -## If the input image is of class uint8 the output is unchanged. -## If the input is of class double the result will be multiplied -## by 255 and converted to uint8, and if the input is of class uint16 the -## image will be divided by 257 and converted to uint8. +## Processing will depend on the class of the input image @var{im1}: +## @itemize @bullet +## @item uint8 - returns the same as input +## @item uint16, double, single, int16, logical - output will be rescaled for the +## interval of the uint8 class [0 255] +## @item indexed - depends on the input class. No value can be above the max of +## the uint8 class (255). +## @end itemize +## ## @seealso{im2bw, im2uint16, im2double} ## @end deftypefn -function im2 = im2uint8(im1) - ## Input checking - if (nargin < 1) - print_usage(); - endif - if (!isgray(im1) && !isrgb(im1)) - error("im2uint8: input must be an image"); +function im = im2uint8 (im, indexed = false) + + ## Input checking (private function that is used for all im2class functions) + im_class = imconversion (nargin, "im2uint8", indexed, im); + + if (indexed) + imax = max (im(:)); + if (imax > intmax ("uint8")) + error ("Too many colors '%d' for an indexed uint8 image", imax); + endif endif - - ## Take action depending on the class of the data - switch (class(im1)) - case "double" - im2 = uint8(255*im1); + + switch im_class case "uint8" - im2 = im1; + ## do nothing, return the same + case {"single", "double"} + if (indexed) + im = uint8 (im) - 1; + else + im = uint8 (im * double (intmax ("uint8"))); + endif + case "logical" + im = uint8 (im) * intmax ("uint8"); case "uint16" - im2 = uint8(im1/257); + if (indexed) + im = uint8 (im); + else + ## 257 is the ratio between the max of uint8 and uint16 + ## double (intmax ("uint16")) / double (intmax ("uint8")) == 257 + im = uint8 (im / 257); + endif + case "int16" + im = uint8 ((double (im) + double (intmax (im_class)) + 1) / 257); otherwise - error("im2uint8: unsupported image class"); + error ("unsupported image class %s", im_class); endswitch + endfunction + +%!assert(im2uint8(uint8([1 2 3])), uint8([1 2 3])); # uint16 returns the same +%!assert(im2uint8(uint16([0 65535])), uint8([0 255])); # basic usage with uint16 +%!assert(im2uint8([0 0.5 1]), uint8([0 128 255])); # basic usage with double +%!assert(im2uint8([1 2]), uint8([255 255])); # for double, above 1 is same as 1 +%!assert(im2uint8(uint16([3 25]), "indexed"), uint8([3 25])); # test indexed uint8 +%!assert(im2uint8([3 25], "indexed"), uint8([2 24])); # test indexed double +%!assert(im2uint8(int16([-32768 0 32768])), uint8([0 128 255])); # test signed integer