HDR Highs and Lows
How is high dynamic range (HDR) imaging used today, and what can you expect in the future?
by Jon Meyer

Digital Design World Conference, February 19, 2004

Jon Meyer

Note: At Digital Design World today, programmer and artist Jon Meyer presented a keynote, "The Future of Digital Imaging: High Dynamic Range Photography." FTPOnline asked Meyer about the definition of high dynamic range (HDR) images, as well as HDR experimentation, advantages, and pitfalls.

FTPOnline: How do high dynamic range (HDR) images differ from 64-bit images?

Jon Meyer: There are three kinds of images:

• Low dynamic range (LDR): These are the mainstream images we use today: JPEG, GIF, and so on. They have 8 bits of information for each channel, and color levels range from 0-255. With this many levels, you get about 8 stops of tonal range, enough to comfortably encode the tonal scale of a paper print.
• Medium dynamic range (MDR): These images have between 8 and 16 bits of information per channel. Marketers tend to use the term "high dynamic range" for anything over 8 bits, but I think that's just spin. JPEG2000 supports medium dynamic range, as do RAW images. Medium dynamic range images can encode a far greater tonal range than we can produce on paper—up to 16 stops—but they still cannot encode the full tonal range of human vision.
• High dynamic range (HDR): True HDR image formats support up to 32 bits per channel, usually in "Float" format with an exponent. In HDR, an RGB image takes up 96 bits per pixel. TIFF Float is a true HDR format. With true HDR formats you can encode the full tonal range that we can perceive with human vision.

FTPOnline: What commercial products or demos are available for the photographer interested in experimenting with HDR images?

Jon Meyer: A list of products and demos is on my resources page: .

Right now, HDR imaging is mostly used for two applications: creating "light maps" for lighting 3D scenes in the special effects industry, and making VR panoramas. You can see some HDR panorama links on my resources page.

It's tedious and fiddly to work with HDR today, but that will change soon.

FTPOnline: When do you expect HDR images to significantly impact mainstream digital photography, and what will be HDR's biggest benefits and pitfalls for the commercial photographer?

Jon Meyer: There are already many cameras available that have 12 to 14 bits of color range (such as Fuji's CCD SR technology). True HDR is further out—the true HDR products available are specialized and expensive. I expect this to change in the next five years.

For a photographer, the two big advantages of MDR and HDR are:

• You get a workable image from almost any lighting condition.
• There is much greater freedom during editing (for example, to dodge/burn or manipulate the image without the banding and aliasing artifacts you get with today's 8-bit images).

Some of the pitfalls are:

• Almost no software packages support HDR today.
• HDR images are up to four times bigger than 8-bit images.
• There is a learning and retooling curve. In particular, photographers have become comfortable with 8-bit images, with colors in the range 0-255. Dealing with floating-point color ranges seems counterintuitive. Software and standards must address these issues.

See for more information.

About Jon Meyer
Jon Meyer is a programmer, teacher, and artist. Jon has 15 years of experience in the software industry, specializing in computer graphics, animation, and user interfaces. He was an adjunct faculty member in the photography department at New York University and has exhibited photographs in New York and Seattle.