High Dynamic Range (HDR) images open up a world of possibilities because they can represent the entire dynamic range of the visible world. Because all the luminance values in a real-world scene are represented proportionately and stored in an HDR image, adjusting the exposure of an HDR image is like adjusting the exposure when photographing a scene in the real world. This capability lets you create blurs and other real-world lighting effects that look realistic. Currently, HDR images are used mostly in motion pictures, special effects, 3D work, and some high-end photography.
You can create an HDR image using multiple photographs, each captured at a different exposure. In Photoshop, the Merge To HDR command lets you create HDR images from multiple photographs. Because an HDR image contains brightness levels that far exceed the display capabilities of a standard 24‑bit monitor or the range of tones in a printed image, Photoshop lets you adjust the preview of the HDR image so it can be viewed on a computer monitor. Some Photoshop tools, adjustments, and filters can be used with HDR images. If you need to print the image or use Photoshop tools and filters that dont work with HDR images, you can convert the HDR image to an 8‑ or 16‑bits-per-channel image.