32-bit Imaging with HDR Toning in Photoshop CS5
Because the tips for capturing a series of bracketed exposures for HDR and processing those raw exposures in Lightroom are covered in the book, the scope of this article will focus mostly on the HDR Toning process. Note that if practical, it’s often a big help to process your HDR images using a high-quality LCD display that can display the widest possible range of grey tones and color shades, rather than using your laptop’s screen or an inexpensive LCD screen. I use a screen made by Eizo (the CG243W), and NEC Displays also makes a series of high-end desktop monitors for graphics pros and photographers. If you’re in the market for a new screen those are two options to consider if you want to do a lot of HDR photography.
Merging Bracketed Exposures
The first step is to bring our images together for Photoshop. If you’re working in Photoshop directly, choose File > Automate > Merge to HDR Pro. If you’re working from Lightroom, select the bracketed exposures you want to use from the Grid view or Filmstrip, right-click, and choose Edit in > Merge to HDR Pro in Photoshop. If you go with the first option, this will open a dialog box for browsing and selecting your files, and for automatically aligning them. Typically I find that if I’ve photographed my scene using a tripod and trigger release, I can get a good result from using this option.
Once the merge process has begun, Photoshop may take a couple minutesdepending on the size of your original raw or jpeg files, how many you are attempting to merge, and the speed of your systemto bring all the shots together into the Merge to HDR Pro interface, shown in Figure 1.
Figure 1 The Merge to HDR Pro main window provides a straightforward set of tools for removing ghost artifacts, mapping tones, and more.
Most of the controls you see above are also included in the HDR Toning adjustment, which we will be covering shortly. They include:
- Remove Ghosts: Uses the image (thumbnail) you choose as the basis for eliminating any blur caused by moving objects (for example, a tree branch moving in the wind).
- Mode pop-ups: Allows you to decide if your output will be 8, 16, or 32-bit, and which tone mapping method to use. In all cases, I prefer either 16- or 32-bit Local Adaptation, as it provides the most flexibility.
- Edge Glow: These sliders control the HDR “glow” and halo effects you may be familiar with from HDR web sites and galleries, by manipulating local contrast. These are most often the “culprit” when an HDR image looks “fake” or “illustrated”, rather than captured with a camera.
- Tone and Detail: these sliders allow you to set the look of the overall exposure, tone down blown out highlights, open up shadows, and add detail or perceived sharpness.
- Color: These two controls allow you to modify the global color saturation and presence.
- Curve: Allows you to fine-tune the contrast beyond what the Tone and Detail controls can do.
The thumbnails at the bottom left of the window represent your HDR exposures. When using Remove Ghosts they can be selected individually to eliminate blur or unwanted movement.
Once you’ve set the mode to 32-bit Local Adaptation, you will see a slider that allows you to map all the tones in the image, such that you can perceive the darkest or brightest details in the scene on your monitor. Dragging the slider to the right will darken down the image; I typically do so until the very brightest parts of the shot are not pure white (unless that was their actual state when photographed). Essentially you’re trying to ensure the brightest details are approximations of what you saw in the original scene, rather than correct the look of the image. All of the exposure and contrast correction will be done in later steps.