GIMP: Making a 'Balanced' Texture v2.6 (.pdf) for FS9, FSX & P3D. PDF file containing instructions for GIMP v2.10.xxand v2.8.xx
How to... either subdue or remove highlights and shadows from your textures (GIMP Only).
Photo Editor (GIMP v2.10.xxor GIMP v2.8.xx)
a. None (this version has the High Pass Filter already installed)
a. The High Pass Filter Plugin
The original location of the High Pass Filter Plugin has closed and is no longer available. Since many of us are still using the previous version (v2.8.xx), we have made it available here. The directions to install this plugin are within the “Readme_HP Filter” of the .zip file. Otherwise, see the latest version of GIMP below.