Mercurial > octave-libtiff
view scripts/image/imwrite.m @ 31211:edbd725ee76c
imwrite: fixed tests to reflect alpha channel behavior for Tiff images
* scripts/image/imwrite.m: modified tests to correctly handled the new
behavior for alpha channel in Tiff images.
* scripts/image/imread.m: added a note in the function documentation
about the alpha channel behavior for Tiff images.
author | magedrifaat <magedrifaat@gmail.com> |
---|---|
date | Tue, 06 Sep 2022 21:12:29 +0200 |
parents | 796f54d4ddbf |
children |
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######################################################################## ## ## Copyright (C) 2008-2022 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 {} {} imwrite (@var{img}, @var{filename}) ## @deftypefnx {} {} imwrite (@var{img}, @var{filename}, @var{ext}) ## @deftypefnx {} {} imwrite (@var{img}, @var{map}, @var{filename}) ## @deftypefnx {} {} imwrite (@dots{}, @var{param1}, @var{val1}, @dots{}) ## Write images in various file formats. ## ## The image @var{img} can be a binary, grayscale, RGB, or multi-dimensional ## image. The size and class of @var{img} should be the same as what should ## be expected when reading it with @code{imread}: the 3rd and 4th dimensions ## reserved for color space, and multiple pages respectively. If it's an ## indexed image, the colormap @var{map} must also be specified. ## ## If @var{ext} is not supplied, the file extension of @var{filename} is used ## to determine the format. The actual supported formats are dependent on ## options made during the build of Octave. Use @code{imformats} to check ## the support of the different image formats. ## ## Depending on the file format, it is possible to configure the writing of ## images with @var{param}, @var{val} pairs. The following options are ## supported: ## ## @table @samp ## @item Alpha ## Alpha (transparency) channel for the image. This must be a matrix with ## same class, and number of rows and columns of @var{img}. In case of a ## multipage image, the size of the 4th dimension must also match and the third ## dimension must be a singleton. By default, image will be completely opaque. ## ## @item Compression ## Compression to use one the image. Can be one of the following: "none" ## (default), "bzip", "fax3", "fax4", "jpeg", "lzw", "rle", or "deflate". ## Note that not all compression types are available for all image formats ## in which it defaults to your @nospell{Magick} library. ## ## @item DelayTime ## For formats that accept animations (such as GIF), controls for how long a ## frame is displayed until it moves to the next one. The value must be scalar ## (which will applied to all frames in @var{img}), or a vector of length ## equal to the number of frames in @var{im}. The value is in seconds, must ## be between 0 and 655.35, and defaults to 0.5. ## ## @item DisposalMethod ## For formats that accept animations (such as GIF), controls what happens to ## a frame before drawing the next one. Its value can be one of the ## following strings: "doNotSpecify" (default); "leaveInPlace"; "restoreBG"; ## and "restorePrevious", or a cell array of those string with length equal ## to the number of frames in @var{img}. ## ## @item LoopCount ## For formats that accept animations (such as GIF), controls how many times ## the sequence is repeated. A value of Inf means an infinite loop (default), ## a value of 0 or 1 that the sequence is played only once (loops zero times), ## while a value of 2 or above loops that number of times (looping twice means ## it plays the complete sequence 3 times). This option is ignored when there ## is only a single image at the end of writing the file. ## ## @item Quality ## Set the quality of the compression. The value should be an integer ## between 0 and 100, with larger values indicating higher visual quality and ## lower compression. Defaults to 75. ## ## @item WriteMode ## Some file formats, such as TIFF and GIF, are able to store multiple images ## in a single file. This option specifies if @var{img} should be appended ## to the file (if it exists) or if a new file should be created for it ## (possibly overwriting an existing file). The value should be the string ## @qcode{"Overwrite"} (default), or @qcode{"Append"}. ## ## Despite this option, the most efficient method of writing a multipage ## image is to pass a 4 dimensional @var{img} to @code{imwrite}, the same ## matrix that could be expected when using @code{imread} with the option ## @qcode{"Index"} set to @qcode{"all"}. ## ## @end table ## ## @seealso{imread, imfinfo, imformats} ## @end deftypefn function imwrite (varargin) if (nargin < 2) print_usage (); endif [filename, ext] = imwrite_filename (varargin{2:end}); fmt = imformats (ext); ## When there is no match, fmt will be a 1x1 structure with ## no fields, so we can't just use 'isempty (fmt)'. if (numfields (fmt) == 0) if (isempty (ext)) error ("imwrite: no extension found for %s to identify the image format", filename); endif warning ("imwrite: unlisted image format %s (see imformats). Trying to save anyway.", ext); __imwrite__ (varargin{:}); else fmt.write (varargin{:}); endif endfunction ## Test input validation %!error <Invalid call> imwrite () # Wrong # of args %!error <Invalid call> imwrite (1) # Wrong # of args %!error imwrite ({"cell"}, "filename.jpg") # Wrong class for img %!error imwrite (1, [], "filename.jpg") # Empty image map %!error imwrite (1, 2, 3) # No filename specified %!error imwrite (1, "filename") # No fmt specified %!error imwrite (1, "filename", "junk") # Invalid fmt specified %!error imwrite ([], "filename.jpg") # Empty img matrix %!error imwrite (spones (2), "filename.jpg") # Invalid sparse img %!function [r, cmap, a] = write_and_read (format, varargin) %! filename = [tempname() format]; %! unwind_protect %! imwrite (varargin{1}, filename, varargin{2:end}); %! [r, cmap, a] = imread (filename, "Index", "all"); %! unwind_protect_cleanup %! unlink (filename); %! end_unwind_protect %!endfunction ## typical usage with grayscale uint8 images %!testif HAVE_MAGICK %! gray = randi (255, 10, 10, 1, "uint8"); %! r = write_and_read (".tif", gray); %! assert (r, gray); ## grayscale uint8 images with alpha channel %!testif HAVE_MAGICK %! gray = randi (255, 10, 10, 1, "uint8"); %! alpha = randi (255, 10, 10, 1, "uint8"); %! [r, ~, a] = write_and_read (".tif", gray, "Alpha", alpha); %! assert (r, cat (3, gray, alpha)); %! assert (a, []); ## multipage grayscale uint8 images %!testif HAVE_MAGICK %! gray = randi (255, 10, 10, 1, 5, "uint8"); %! r = write_and_read (".tif", gray); %! assert (r, gray); ## multipage RGB uint8 images with alpha channel %!testif HAVE_MAGICK %! gray = randi (255, 10, 10, 3, 5, "uint8"); %! alpha = randi (255, 10, 10, 1, 5, "uint8"); %! [r, ~, a] = write_and_read (".tif", gray, "Alpha", alpha); %! assert (r, cat (3, gray, alpha)); %! assert (a, []); ## typical usage with RGB uint8 images %!testif HAVE_MAGICK %! rgb = randi (255, 10, 10, 3, "uint8"); %! r = write_and_read (".tif", rgb); %! assert (r, rgb); ## RGB uint8 images with alpha channel %!testif HAVE_MAGICK %! rgb = randi (255, 10, 10, 3, "uint8"); %! alpha = randi (255, 10, 10, 1, "uint8"); %! [r, ~, a] = write_and_read (".tif", rgb, "Alpha", alpha); %! assert (r, cat (3, rgb, alpha)); %! assert (a, []); ## multipage RGB uint8 images %!testif HAVE_MAGICK %! rgb = randi (255, 10, 10, 3, 5, "uint8"); %! r = write_and_read (".tif", rgb); %! assert (r, rgb); ## multipage RGB uint8 images with alpha channel %!testif HAVE_MAGICK %! rgb = randi (255, 10, 10, 3, 5, "uint8"); %! alpha = randi (255, 10, 10, 1, 5, "uint8"); %! [r, ~, a] = write_and_read (".tif", rgb, "Alpha", alpha); %! assert (r, cat (3, rgb, alpha)); %! assert (a, []); %!testif HAVE_MAGICK %! gray = repmat (uint8 (0:255), 100, 1); %! [g] = write_and_read (".jpeg", gray); %! assert (g, gray, 2); %!testif HAVE_MAGICK %! gray = repmat (uint8 (0:255), 100, 1); %! [g] = write_and_read (".jpeg", gray, "quality", 100); %! assert (g, gray); %!function compression = get_bmp_compression (ext, cmap = [], varargin) %! gray = repmat (uint8 (0:255), 100, 1); %! filename = [tempname() ext]; %! unwind_protect %! if (isempty (cmap)) %! imwrite (gray, filename, varargin{1:end}); %! else %! imwrite (gray, cmap, filename, varargin{1:end}); %! endif %! fid = fopen (filename); %! unwind_protect %! compression = fread (fid, 31)(end); %! unwind_protect_cleanup %! fclose (fid); %! end_unwind_protect %! unwind_protect_cleanup %! unlink (filename); %! end_unwind_protect %!endfunction ## BMP images must be saved uncompressed by default %!testif HAVE_MAGICK <*45565> %! assert (get_bmp_compression ("", [], "BMP"), 0); %! assert (get_bmp_compression ("", [], "bmp"), 0); %! assert (get_bmp_compression (".BMP"), 0); %! assert (get_bmp_compression (".bmp"), 0); %! assert (get_bmp_compression (".bmp", [], "bmp"), 0); %! assert (get_bmp_compression ("", gray (256), "bmp"), 0); %! assert (get_bmp_compression (".bmp", gray (256), "Compression", "rle"), 1);