Hi, HDRI stands for High Dynamics Range Images. HDRI is a particular type of images that have more dynamic than the traditionnal bitmaps (meaning that you can have very high intensity regions and low intensity regions) For example, if you had a picture of the sky, the sun is much brighter than the sky. With a normal bitmap, the sky would be black and the sun white... An HDRI picture would allow you to have a very bright sun and still have the variation of the sky. Carrara Studio does not support HDRI images at this point. However in most cases you can get the same effect by using a combination of images and light sources (example, use a distant light for the sun and a bitmap for the sky) and the GI engine will do the rest. Charles