COMBINE NORMAL
This Photoshop script combines normal maps using the Detail Oriented method by Colin Barré-Brisebois and Stephen Hill
(explained here).
Combine Normal will combine all visible layers from your document (8 or 16 bit/ channel).
You can adjust the intensity of each layer.
Combine Normal installer for Adobe Photoshop CS2 - CS6: (seperate files also available at the bottom of this page)
INSTALLATION INSTRUCTIONS
Run the x64 or x86 installer to copy the script file to the correct location.
You can also copy the files yourself if you want to. You need to install the
Visual Studio 2013 Redistributables.
You will also need to copy 'Combine Normal.jsx', 'CombineNormal_(x86)(x64).dll' and 'CombineNormals_(x86)(x64).exe' to
'C:\Program Files (x86)(x64)\Adobe\Adobe Photoshop
VERSION\Presets\Scripts'