OctaneRender® can dynamically compress textures to use 1/3 - 1/8 of the VRAM of normal RGBA, grayscale and float textures without compression. Compressed textures incur zero speed loss at render time, though there is an initial time hit the first time the textures are compressed. Texture Compression is a technology commonly used in GPUs to make VRAM more efficient. The names in the "Texture Import Type" menu may be confusing at first (in the image below) but these names are the methods currently used in GPU texture compression (BC[n] block formats). You can read more about these methods in the following links: 

http://www.reedbeta.com/blog/understanding-bcn-texture-compression-formats/ 

http://renderingpipeline.com/2012/07/texture-compression/


TEXTURE COMPRESSION