Update for consistency branch

astra-toolbox · Jan 17, 2020 · 1e3ac43 · 1e3ac43
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diff --git a/conf.py b/conf.py
@@ -60,9 +60,9 @@
 # built documents.
 #
 # The short X.Y version.
-version = '1.9.0.dev11'
+version = '1.9.9.dev1'
 # The full version, including alpha/beta/rc tags.
-release = '1.9.0.dev11'
+release = '1.9.9.dev1'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.

diff --git a/index.rst b/index.rst
@@ -19,15 +19,15 @@ The source code of the ASTRA Toolbox is available on `GitHub <https://github.com
 Latest News
 -----------
 
+* In the latest development version of ASTRA (1.9.9.dev), we have made some consistency improvements to the grey value output ranges of the FP and BP operations. See the `News section <news.html>`_ for more information.
+
 * For those visiting `ICTMS 2019 <http://ictms2019.org/>`_ in Australia, we will host `an ASTRA workshop <ictms.html>`_ there on 22 July 2019.
 
 * Windows Matlab/Python packages of the current 1.9.0.dev version of ASTRA
   git master are now available for download below. These require CUDA 9.0+.
 
 * We now have development Python packages available from ASTRA git master on conda. Quick installation instructions: ``conda install -c astra-toolbox/label/dev astra-toolbox`` .
 
-* From 5 to 7 April 2017, the Vision Lab organizes an ASTRA Toolbox training session at the University of Antwerp.
-
 * 7 dec 2016: ASTRA v1.8 released
 
 

diff --git a/news.rst b/news.rst
@@ -4,6 +4,26 @@ News and version history
 News
 ----
 
+* 2020-01-17: Consistency changes in development version of ASTRA
+
+ We have changed the way gray values in forward projections, backprojections and reconstructions scale with the size of detector pixels.  This does not impact geometries where the detector pixels have size 1 in 2D, or 1x1 in 3D.
+
+ In the upcoming ASTRA 2.0, and starting from version 1.9.9.dev, for all geometries and projectors, the value of a pixel in a forward projection is approximately the value of the line integral of the corresponding ray through the volume.
+
+ Of course the interpolation/projection method used will still determine the exact set of pixels contributing to a ray and the exact value as before.
+
+ All backprojectors and reconstruction algorithms have been adapted to match the forward projection.
+
+ Before this change, a decision made in the early pre-1.0 days of ASTRA to make detector values scale linearly with the area of detector pixels led to some in hindsight mathematically unresolvable inconsistencies in behaviour between parallel and fan/cone geometries, and behaviour with oblique projections. The new definition resolves this inherent inconsistency.
+
+ Specific changes:
+
+ * all parallel beam 2D projectors (CPU and CUDA) have been changed as above
+ * the 2D fan beam CPU projectors have been changed as above
+ * the 2D fan beam CUDA projector did not require changing
+ * the 3D CUDA backprojectors have been changed as above. The forward projectors did not require changing
+ * the 2D fan beam and 3D cone beam CUDA backprojectors now have an improved approximate match with the respective forward projectors
+
 * 2019-07-09: Development packages of 1.9.0.dev are now available for download.
 
   The Windows packages now require CUDA 9.0 or higher.