HDR means High Dynamic Range = Imagery in High Dynamic Range
A HDR image is made up of a series of standard images (JPG) shot with different exposures. The first and the last in this series must make it possible to distinguish the most luminous details for one, and the darkest in the other.
A classic image (called LDR for Low Dynamic Range) is composed of pixels with values between 0 to 255 for each red, green and blue plan. Here we are talking about 8- or 16 bits/pixel images.
But, in fact, this palette is not sufficient to properly render the difference between very dark and very shiny areas. This is the reason why HDR images are encoded with biggest values (32 bits/pixels), allowing users to reveal the biggest constrasts in the same image
Some digital cameras enable you to reproduce HDR images, but this is not the norm.
The simplest method, is to take various shots of the same scene with a standard digital camera, and and then fuse these LDR images into one single HDR image.
In this instance, you need to use a technique called « bracketing » which consists of taking the same photograph with different shutter speeds.
Once you have obtained your HDR image, it will contain too many details to be viewed on a standard computer screen, and needs to be made “displayable”, whilst preserving the different levels of details.
This is the principle of « tone mapping ».
Once the image has been « tone mapped » you will obtain a HDR image converted to a standard jpeg format. A « tone mapped » image is a HDR image from which the various exposures were flattened in order to make it “displayable” on a standard screen.
Autodesk® Stitcher™ Unlimited now makes it possible to use images utilizing up to 32 bits per channel and is available with the following formats in input/ output:
OpenEXR (.exr) on 16 and 32 bits per channel Radiance RGBE (.hdr)
For further general information about HDR images, you can 
