adding detailed documentation on reconstruction methods

Author: dkazanc

README.rst

@@ -34,7 +34,7 @@ Conda environment
 
    $ conda create --name httomolibgpu # create a fresh conda environment
    $ conda activate httomolibgpu # activate the environment
-   $ conda install -c conda-forge cupy==12.3.0 # for linux users
+   $ conda install conda-forge::cupy==12.3.0
    $ pip install httomolibgpu
 
 Setup the development environment:

docs/source/reference/methods.rst

@@ -38,7 +38,7 @@ Modules from `Data denoising` can be used as post-processing tools. For instance
 Stripes removal module
 ^^^^^^^^^^^^^^^^^^^^^^
 
-Modules from `Stripes removal` normally used as pre-processing tools. Stripes removal is equivalent to removing ring artefacts in the reconstructed images.
+Modules from `Stripes removal` are normally used as a pre-processing tool. Stripes removal is equivalent to removing ring artefacts in the reconstructed images.
 
 
 .. toctree::
@@ -49,6 +49,23 @@ Modules from `Stripes removal` normally used as pre-processing tools. Stripes re
    methods_list/remove_stripe_ti
    methods_list/raven_filter
 
+
+.. _image_reconstruction_module:
+
+Image reconstruction module
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Modules from `Image reconstruction` are needed in order to reconstruct data from the set of sinograms into a reconstructed volume. The reconstruction methods can be divided into two groups: Direct methods and Iterative methods. 
+The former are faster and suitable for the majority of well-sampled and well-exposed data. The latter are more complex and slower methods when the data is erroneuos or/and undersampled. 
+
+.. toctree::
+   :glob:
+
+   methods_list/LPRec3d_tomobar
+   methods_list/FBP3d_tomobar
+   methods_list/FBP2d_astra
+   
+
 .. _data_rescale_module:
 
 Data rescale module

docs/source/reference/methods_list/FBP2d_astra.rst

@@ -0,0 +1,23 @@
+.. _method_FBP2d_astra:
+
+FBP using ASTRA-Toolbox
+^^^^^^^^^^^^^^^^^^^^^^^
+
+**Description**
+
+This module performs Filtered-Back-projection direct reconstruction using `ASTRA-Toolbox <https://astra-toolbox.com>`_. It is an implementation of parallel-beam 
+`FBP <https://astra-toolbox.com/docs/algs/FBP.html>`_ reconstruction method by ASTRA with the related parameters exposed (see the adjustable parameters bellow).
+
+
+.. note:: This is the slowest direct reconstruction method in the library and it is recommended to use other methods, such as, :ref:`method_FBP3d_tomobar` or :ref:`method_LPRec3d_tomobar`.
+  
+**Where and how to use it:**
+
+This reconstruction method can be used as a back-up option if other reconstruction algorithms.
+
+**What are the adjustable parameters:**
+
+
+**Practical example:**
+
+

docs/source/reference/methods_list/FBP3d_tomobar.rst

@@ -0,0 +1,15 @@
+.. _method_FBP3d_tomobar:
+
+FBP3D (ToMoBAR)
+^^^^^^^^^^^^^^^
+
+**Description**
+
+  
+**Where and how to use it:**
+
+
+**What are the adjustable parameters:**
+
+
+**Practical example:**

docs/source/reference/methods_list/LPRec3d_tomobar.rst

@@ -0,0 +1,16 @@
+.. _method_LPRec3d_tomobar:
+
+Log-Polar 3D (ToMoBAR)
+^^^^^^^^^^^^^^^^^^^^^^
+
+**Description**
+
+  
+**Where and how to use it:**
+
+
+**What are the adjustable parameters:**
+
+
+**Practical example:**
+