I would like to share...
Smart IBL
Lighting a 3d scene with panoramic HDR imagery has revolutionized computer graphics.
Never before has it been so easy to replicate real lighting situations. Every off-the shelf 3d software nowadays includes a Global Illumination (GI) render engine that can be fueled with HDRIs to create photorealistic renderings.
However, a common pitfall is that GI takes longer to render, especially when using high-res HDRIs. It takes ridiculously high quality settings to get rid of sampling noise or flickering. That's why, in practice it’s much more efficient to use a blurred low-res image for diffuse lighting, and a high-res image for reflections only...
....Smart IBL is not a shader or render algorithm, it’s just an idea. It was designed as an open system, completely transparent to artists and developers - flexible enough to power an entire company pipeline, and portable enough to work in every 3d application. And most importantly, it's completely free.
http://www.hdrlabs.com/sibl/index.html
Enjoy :)