From the Readme:
This is a demo of Depth Of Field, where the viewing camera focuses on a portion of the scene. In this demo camera focus is manually controlled by the user (see Usage).
This demo will operate with with either OpenGL or Direct3D9 (as long as the graphics hardware is capable).
F1/F2 - alter camera Range
F3/F4 - alter camera Focus
F5/F6 - alter camera Blur0 and Blur1 parameters
F7/F8 - alter camera Distance
WASD keys to move camera.
Alt-F4 or Escape key to exit.
Latest DirectX 9.0b drivers [www.microsoft.com/directx],
Latest DirectX9 drivers for your graphics hardware [from your HW vendor].
Latest OpenGL drivers for your graphics hardware [from your HW vendor].
Direct3D9: Vertex Shader 2.0 support, or better
Pixel Shader 2.0 support, or better.
OpenGL: Vertex Program 2.0 support, or better
Fragment Program 2.0 support, or better.
This demo may require the Visual Studio 2005 Redistributable Files installed on your machine. These can be obtained from http://www.sio2.g0dsoft.com in the "Misc" section of "Downloads".
This is a modified version of a demo by "posttool" from the Irrlicht forums [accessible via http://irrlicht.sourceforge.net]. Support for Direct3D9 was added, shaders converted from GLSL to HLSL, bugfixes and enhancements. Credit also goes to "omaremad" from the Irrlicht forum for the original hdr code which was the inspiration for the "posttool" demo.