Tuesday, June 24, 2008
XDR, Part III
Double exposure gives you two times the image information to use in a final image
This is the third in a series of “R/Evolution” columns on Extended Dynamic Range (XDR). Extending dynamic range has become increasingly mainstream for professional photographers as software has become more powerful and new techniques have been unveiled.
Reproducing the full range of tones or brightness values seen by the human eye is one of the most fundamental challenges in photography. Capture, display and print technologies are all limited when compared to the ability of the human eye to see a wide dynamic range. Recent advances in technology enable you to exceed these limitations.
Techniques for extending dynamic range span the gamut from simple to complex. Before resorting to complex solutions, try simpler ones first. Apply the principle of Occam's Razor. (See the “R/Evolution” columns in the two previous issues of DPP for more on this.)
You can distill the entire zone system down to one phrase: expose for the shadows, develop for the highlights. While the principle holds just as well for the 21st century as it did for the 20th century, today we can extend this principle further. Expose for the shadows and expose for the highlights—then, using software, blend the two exposures together to get the best of both.
Bracket: Make Multiple Exposures
When the dynamic range of a scene substantially exceeds the capabilities of a camera, bracket brightness with multiple exposures and merge them in Photoshop.