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diff NEWS @ 17332:eb7e9a991ffb

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Implement writing of CMYK and fix writing of image alpha channel (bug #32986). * __magick_read__.cc (bitdepth_from_class, init_encode_image): new functions created from pieces of encode_indexed_images () to be used by the other encode image functions. (encode_indexed_images): make use of new bitdepth_from_class(), and init_encode_image() functions. (encode_bool_image): rewritten to match flow of the other encode functions, use fortran_vec for performance, and use only 4th dimension for frames. (encode_uint_image): completely rewritten to identify images of CMYK type and not confuse them with RGB plus alpha channel. Now accepts the alpha channel as separate argument. Image argument must now be of same class as the template. (__magick_write__): changed to match new API for the encode functions. * private/__imwrite__.m: set default and input check for alpha channel option. * imwrite.m: document alpha channel option as separate argument. * NEWS: announce rewrite of the image IO functions and warn about possible backwards incompatibilities.
author Carnë Draug <carandraug@octave.org>
date Mon, 19 Aug 2013 16:11:18 +0100
parents 5ff843d739fc
children 9b7ca74489c7
line wrap: on
line diff
--- a/NEWS	Mon Aug 26 21:26:25 2013 +0200
+++ b/NEWS	Mon Aug 19 16:11:18 2013 +0100
@@ -138,9 +138,27 @@
 
     Other changes include fixes to the way indexed images are read from a
     colormap depending on the image class (integer images have a -1 offset to
-    the colormap row number), and always returning the actual indexed image
-    with imread instead of a RGB image if the colormap was not requested
-    as output.
+    the colormap row number).
+
+ ** The imread and imwrite functions have been completely rewritten
+
+    The main changes relate to the alpha channel, support for reading and
+    writing of floating point images, implemented writing of indexed images,
+    and appending images to multipage image files.
+
+    The issues that may arise due to backwards incompatibility are:
+
+      * imwrite no longer interprets a length of 2 or 4 in the third dimension
+        as grayscale or RGB with alpha channel (a length of 4 will be saved
+        as CMYK image).  Alpha channel must be passed as separate argument.
+      * imread will always return the colormap indexes when reading an indexed
+        image, even if the colormap is not requested as output.
+      * transparency values are now inverted from the previous Octave versions
+        (0 is for completely transparent instead of completely opaque).
+
+    In addition, the function imformats has been implemented to expand
+    reading and writing of images of different formats through imread
+    and imwrite.
 
  ** The colormap function now provides new options---"list", "register",
     and "unregister"---to list all available colormap functions, and to