The New York Times has an interesting article on HDR - High Dynamic Range photography. HDR allows photographers to combine multiple exposures to bring out the full range of tonal values in a scene, retaining detail in dark shadows as well as bright highlight areas. The results, like these mouthwatering images by photog Kris Kros, are sometimes hyper-realistic, making a photograph look like a hybrid photo-cum-painting. There are several programs for rendering HDR images, including Photoshop CS2. If you're interested in trying out the HDR features in Photoshop CS2, here are the basics:The trick is to take several shots of the same scene at slightly different exposures and merge the images into one 32-bit HDR file in Photoshop (CS2 only). Shoot in RAW format. Be sure to use a tripod so your camera doesn't move between shots. Bracket exposures by changing shutter speed one stop for each shot, without changing your aperture. In Photoshop, choose File>Automate>Merge to HDR, and browse to your bracketed shots. Choose 32 bits as the bit depth if you want to retain all of the tonal information. Photoshop will merge the multiple exposures into one 32-bit file.
The merged image may look washed out at first because an HDR image contains a larger dynamic range than your monitor can display. You can adjust Photoshop's preview of the merged image by choosing View>32-bit Preview Options and adjusting Exposure, Gamma, and Highlight Compression settings there. These settings do not affect the image -- only the way it appears on your monitor. To adjust the image itself, choose Image>Adjustments>Exposure. In the Exposure dialog box, use the Exposure slider to adjust the highlights, the Offset slider to adjust shadows and midtones, and the Gamma slider to adjust , well, the gamma. Save the 32-bit file in Radiance (.hdr) format. If you want to manipulate the image further in Photoshop, convert it to 16 bits so you have access to more tools and features. You can print the 16-bit file, or convert it to 8-bit for printing.
1. I read the Time piece and looked at the accompanying links (http://www.nytimes.com/2006/08/03/technology/03basics.side.html). It is worth the time.
Not being a tripod toting type, I opt for viewfinder cameras with image stablization, but I can appreciate the HDR technique.
Perhaps THE most impressive thing about that piece was a link to Sean McHugh's gallery of breathtaking photos of Cambridge at: http://www.cambridgeincolour.com/cambridge-gallery.htm. We all have a lot of things to do these days, but a trip to this site is worth it.
Posted at 10:07AM on Aug 4th 2006 by Don O'Shea