By Stan Sholik
Interest in high dynamic range (HDR) imaging has spawned a number of new and innovative software products for photographers, including Unified Color’s HDR Expose software, reviewed here earlier this summer. But these HDR solutions are all standalone programs, and many photographers are so comfortable with the available tools in Adobe Photoshop that they are reluctant to purchase software that requires them to leave Photoshop and open another program. For casual HDR users this may be especially true now that Merge to HDR PRO is included as part of Photoshop CS5.
For these photographers, Unified Color’s introduction of the 32 Float plug-in for Photoshop offers a solution. 32 Float expands the limited Photoshop 32-bit toolset and allows the user to perform advanced image editing in the 32-bit workspace. While the tools in 32 Float are identical to those in HDR Expose, 32 Float lacks the ability to merge captures into a 32-bit HDR image—Photoshop Merge to HDR or another HDR program must be used for this task.
Once you open a 32-bit file in Photoshop, you open 32 Float from the Filter>Unified Color drop-down menu (above). Your image reopens in a separate window. The interface is virtually identical to that of HDR Expose but with a smaller toolset since it does not need to handle the image merging functions.
The Preferences dialog box allows you to select the option of saving your result as a separate layer in your original image. This is useful for many HDR images.
The HDR Brightness Histogram show the full range of values in the 32-bit image. The lighter gray section of the histogram shows the range of values that would be present in the lower bit image with the current settings. For this image, some shadow values at the tail of the curve and lots of highlight values at the right of the curve will be clipped. Note the valley where midtones should be that make this a particularly difficult image to correct.
The top of the tool panel on the right is dominated by the interactive HDR histogram (above). This visual aid shows the full range of values in the 32-bit image with a lighter gray area representing the subset of these values that would be present in an 8-bit or 16-bit (lower bit range) image. 32 Float gives you the tools to adjust your image so that the values you want to reproduce in a lower bit value image lie within the lighter gray range of the histogram. The zoomable preview image that dominates the center of the interface allows you to preview the visual effect of your adjustments.
A Dynamic Range Mapping tool provides a useful starting point for your adjustments if your image contains a good midtone value. Unfortunately, the HDR image I chose to work with was mostly highlights and shadows, with a big valley in the histogram where the midtones would be. So I went immediately to the advanced tools.
You use the Brightness/Contrast tools to make major changes in the tonal range of the image to fit the 32-bit values to the down-sampled section of the curve. Here only a few highlight values are now being clipped.
The Brightness/Contrast tools have the greatest effect on the tonal range. Brightness adjusts the overall range of the lower bit range area relative to the 32-bit values. Contrast adjusts the width of the lower bit range area to include more of the 32-bit values. These adjustments can result in haloing in high contrast areas, so there is a halo reduction tool in the same toolset. There is also a local contrast slider to bring back lost contrast in the midtones. Overusing this slider results in the “grunge” look found in many HDR images.
The Shadow/Highlight tools allow you to save the last bits of highlight and shadow information if you decide to do so.
Subtler changes to the image and visible in the histogram are available with the Shadow/Highlight tool. Sliders in this toolset will bring in or lose information in their respective areas. There are halo reduction and local contrast adjustments available here also.
The Veiling Glare tool removes the “haze” created by combining multiple images in HDR software. It acts similarly to setting a black point in conventional imaging software.
Photoshop has no technique for adjusting white balance in a 32-bit image, but 32 Float offers this unique tool. You can assign a color temperature or move a spot around in the yellow-blue/green-magenta square to fine tune white balance.
A Veiling Glare tool essentially sets a black point in the image, with an additional slider to set the level of black or gray. And the White Balance tool offers a Kelvin setting and a yellow-blue/green-magenta color square to visually adjust white balance. There is also a Saturation toolset that allows the adjustment of individual colors as well as overall saturation.
A very interesting tool is Color Tuning. You can selectively adjust up to three different colors. Here I have targeted the yellow flowers. I could change their color within the range displayed in the box, but I only wanted to brighten them, which I did with a 1.50 EV adjustment.
But I found the most interesting tool to be the Color Tuning toolset. With it you can adjust up to three specific colors over a range of hues and brightness. Using Color Tuning, I brightened the value of the yellow brittlebush flowers and changed the hue of the sky. With other images it would be very useful in removing the yellow cast that always finds its way into tree leaves in HDR images.
Yet, even with all of these tools, I wasn’t able to create a final image with the kind of impact that I had created using the same set of initial images in other HDR programs. This could be due to my initial creation of the 32-bit HDR image in CS5, or the lack of range or adjustments in 32 Float, or my own learning curve. Nevertheless, 32 Float delivers an advanced set of tools to adjust 32-bit HDR images, or any 32-bit image that you create. Unlike most HDR programs that create a 32-bit image then downsample it to 16 bits for adjustments, all of the adjustments in 32 Float are done in the 32-bit space. This alone adds a valuable tool to the photographer’s toolbox.
This is an 8-bit down sample of the original 32-bit HDR image I created from five originals using Photoshop CS5 Merge to HDR.
This is the final result of my efforts after applying adjustments in 32 Float.
32 Float is available for $99 ($79 special available at post time, Sept. 30, 2010) at unifiedcolor.com. You can download a fully-functional 30-day free trial. Visit the website to view video tutorials, download manuals and to find more information.
Stan Sholik is a commercial/advertising photographer in Santa Ana, CA, specializing in still life and macro photography. His latest book, “Professional Filter Techniques for Digital Photographers,” covering both on-camera analog and post-production digital filters is published by Amherst Media.
OS: Intel-based Mac OS 10.5 (Leopard) or 10.6 (Snow Leopard), 32-bit or 64-bit Windows (XP, Vista, Windows 7).
Adobe Photoshop: Requires CS3, CS4 or CS5 (Note: 32 Float will not work with Photoshop Elements).
CPU: Dual-core 2.0GHz minimum; quad-core, 2.8GHz is recommended for best performance.
RAM: 2GB minimum, recommend 4GB.
Video: Recommend 128M video memory minimum.