Gadget Bag: High Dynamic Range Software

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High Dynamic Range Software—even the words sound exciting. Dynamic range describes the breadth of differences in luminance between the darkest (pure black) and lightest (absolute white) areas in an image. Increasing dynamic range translates into making more details visible in shadow areas while simultaneously retaining details in the bright highlights. Dynamic range that suffers on either end is said to have blocked shadows, blown highlights or both.

Adobe Photoshop CS5 HDR Pro

Some cameras have an HDR or pseudo-HDR function built in. They stretch the limits by compensating for underexposed shadows or by capturing more than one image (each at a different exposure) and blending them internally following a set of rules. Those of us with cameras that don’t broaden dynamic range automatically can follow a similar procedure and get equal or better results. In a nutshell, we bracket the exposure and merge all of the data from the image files using specialized software. When executed perfectly, the resultant image contains the shadow detail from the slightly overexposed images and the highlight detail from the slightly underexposed shots—plus all of the midtones.

Tone Mapping. It sounds simple, and it is—sort of. It’s the process in which the colors of a 32-bit HDR image are mapped to an image with lower bit depth. HDR software merges the multiple image data into one 32-bit-per-channel-per-pixel image, but shrinks it back to a useable size that can be displayed on your monitor. Along the way, the dynamic range of the 32-bit image is compressed to fit into a 16- or 8-bit-per-channel image. The larger file provides more data for adjustment and manipulation while the smaller image file is more easily displayed and printed. If your software allows it, always save the 32-bit image so you can do additional editing of the full data set later.

There are several software applications that do the HDR heavy lifting for you, including the newly refreshed Adobe Photoshop CS5. One of the many exciting new features found in Photoshop CS5 is HDR Pro. Adobe has greatly enhanced the simple HDR function by adding extended controls, an enhanced dialog box and improved image processing. The processing rules (algorithms) have been refined and now provide more accurate alignment of source files. CS5 can automatically deghost the annoying double vision that can occur when subjects have moved during image capture—or you can designate one single source file that’s to be used as the reference point for deghosting. HDR Pro offers extended tone-mapping tools and adjustment controls, and allows users to save their favorite styles as presets for future application. You even can simulate the HDR effect by applying the new HDR Toning feature to a single image. Contact: www.adobe.com.

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Ever Imaging Ltd. HDR Darkroom

A relative newcomer to the HDR arena, Ever Imaging Ltd., introduced HDR Darkroom in November 2009. Their website offers a useful tutorial and thorough explanation of HDR technology. HDR Darkroom allows you to create an HDR image from multiple compressed or RAW files, or one single linear TIFF file in 16-bit-per-channel format. It also functions as a RAW converter. Their claimed advantage is that they provide three separate tone-mapping engines. One is global while the other two are patented local tone-mapping engines: Local Tone Balancer (which balances tones to reveal detail in both shadow and highlights) and Local Tone Enhancer (which extracts hidden details). Local tone-mapping technologies take into account information about neighboring pixels during the mapping process and are said to work more like human vision in that respect. Contact: www.hdrdarkroom.com.

HDRsoft Photomatix Pro

Photomatix Pro from HDRsoft has garnered the lion’s share of popularity votes among HDR photographers because of the consistently outstanding results it produces. Like all HDR applications, Photomatix Pro works its magic by combining data from multiple images of the same scene taken at different exposure settings. How it differs is that it performs either HDR tone mapping or Exposure Fusion (their name for reducing noise while blending differently exposed photographs into one image). For best results, Photomatix recommends using three photos separated by two EVs (i.e., two full stops) or five shots separated by one EV. You can use the Bracketing feature on your DSLR to automate the process, but be aggressive when setting the differential increments. In some cases, you’ll need a tripod. Photomatix Pro and Photomatix Light have an automatic alignment option for handheld shots. Images processed with the trial version are watermarked, but it’s fully functional and a great way to find out if HDR is your cup of tea. You can remove the watermark after you buy a license key. Contact: www.hdrsoft.com.

Image Content Technology Lucis Pro 6

One might say using Lucis Pro 6 from Image Content Technology to perform HDR transformations is like using a sports car to drive to the grocery store—there are so many other fascinating things you can do. You can create HDR effects from a single image, restore underexposed and overexposed images, pull out contrast patterns in the image, create a watercolor effect where the effect varies throughout the image and add texture. Also, Lucis Pro 6 is simple to use. The GUI is intuitive, with easy-to-use sliders that have understandable labels like Enhance Detail. Besides merging multiple image files into an HDR image, you can create HDR effects from a single image, restore underexposed and overexposed images and eliminate radial artifacts or add texture. By applying the diverse creative controls, you can produce an infinite number of variations of your masterpiece. Contact: www.lucispro.com.

Unified Color Technologies HDR PhotoStudio 2

HDR PhotoStudio 2 from Unified Color Technologies provides real 32-bit color-editing tools so you can fully process your HDR files using all of the 32-bit floating point data with the greatest amount of control and detail before having to tone map to 16 or 8 bits. Explains Marketing Director John Omvik, “Most of the other HDR applications do the merge in 32-bits and then convert to 16 or 8 for any color processing. Staying in 32-bits allows us to implement very powerful algorithms to correct for issues such as halo artifacts using all the image information.” HDR PhotoStudio 2 also preserves color integrity. Adjust anything related to brightness (brightness, contrast, shadow/highlight, sharpness), and the color tones of your image don’t change. Conversely, when color tones (such as in white balance, saturation, color tuning) are changed, the image brightness and contrast remain unaffected. Contact: www.unifiedcolor.com.