TruHDR is a really nice HDR (High Dynamic Range photography) app that has been around a long time for iOS. It improves on Apple's built-in implementation that lets you take pictures with much better dynamic range than a single shot can provide by using an algorithm to combine three photos taken at different exposures.
Now, TruHDR is being offered at a bargain price for Mac users to try. At an introductory price of US$3.99 you can combine several exposures to produce a new image that gives you better shadow detail and avoids blown-out skies.
TruHDR claims to be able to merge up to 100 images into one HDR image, and I tried with five and seven exposure bracketed images, which worked fine. Other similar HDR apps for Mac range in price from $29.00 to $100.00 and can only merge three to seven images. Of course, most photographers won't have a hundred images to combine, but it is good to see that feature exists if it's ever needed.
The app is simple to use: click on import and select your images. They appear in a scrolling pane on the left of the app GUI. You can then do a simple merge if your shots were made from a stable tripod or a merge and align if you were shooting handheld and may have swayed a bit between exposures.
When the images are combined, an edit panel shows up to let you adjust contrast, brightness, saturation, sharpness, tint and color temperature. There are also presets to render the image in various styles, including sepia tones and mono.
I thought TruHDR worked quite well, and it is certainly one of the most reasonably priced HDR apps around for OS X. It doesn't have all the controls I would associate with HDR apps, like strength, tone-mapping or shadow detail, but I could get very nice looking images with the controls that are provided. The developer tells me those additional controls are coming in later updates. I tested some multiple bracketed RAW files from my recent trip to Monument Valley in Arizona, and was pleased with the results. Even though all my photos were taken on a tripod, the merge and align mode worked better at providing me with sharp final output.
If you are serious about HDR, my app of choice is Photomatix, but it is almost a hundred dollars. If you've explored HDR on the iPhone and want to see what you can do from your DSLR images, TruHDR is an easy buy.
There are a couple of rough edges in version 1, but judging from the success of TruHDR for iOS, I know the developer will continue to enhance and improve the program. While some of the other Mac apps offer more editing/rendering features, they are all more expensive, and it looks like TruHDR will get similar editing enhancements soon.
TruHDR requires OS X 10.8 or later, and a 64-bit processor.