How to Work with Photoshop CC Merge to HDR Pro
When you have the exposures from which you want to create your HDR masterpiece, you need to put them together using the Merge to HDR Pro feature in Photoshop CC.
You can open Merge to HDR Pro either through Photoshop’s File→Automate menu or you can select the images to use in Bridge and use Bridge’s menu command Tools→Photoshop→Merge to HDR Pro.
If you open through Photoshop, you’ll either need to open the images into Photoshop first, or navigate to and select the images to use. If you browse, the files must all be in the same folder on your hard drive.
Be patient with Merge to HDR Pro — it has a lot of work to do before you get to play with the combined exposures. When the calculations are done, the Merge to HDR Pro window opens (as shown).
Each of the images in the merge is shown as a thumbnail below the preview. You can deselect each image to see what impact it has on the combined exposure. (After you click the green checkmark, give Merge to HDR Pro a couple of moments to redraw the preview.) If you’re working with seven exposures and one seems to degrade from the overall appearance, leave that thumbnail’s box deselected.
By default, Merge to HDR Pro assumes that you want control over the image right away and sets the Mode menu to 16-bit color and Local Adaptation. You then have a few more options, including the Curve panel (as shown).
So, what are all those options you see?
Preset: If you have a series of similar images that require the same adjustments, you can save and load presets.
Remove Ghosts: When you're capturing multiple exposures, especially outdoors, moving objects in your image may have left "ghosts" behind. This option helps minimize those moving objects.
Edge Glow: Use the Radius and Strength sliders in combination to increase the perceived sharpness of the image.
Tone and Detail: Think of the Gamma slider as your contrast control. Dragging to the right flattens the contrast between highlights and shadows; dragging to the left increases the contrast. The Exposure slider controls the overall lightness (to the right) or darkness (to the left) of the image, just like the Exposure slider in Camera Raw. The Detail slider sharpens the smallest bits in the image.
Advanced: The Advanced tab shares space with Curve in Local Adaptation. The Shadow and Highlight sliders here control the lower and upper parts of the image’s tonal range.
For both sliders, dragging left darkens and dragging right lightens. The Vibrance slider controls the saturation of the near-neutral colors and Saturation controls all of the colors in the image. (These sliders, too, are comparable to their counterparts in Camera Raw.)
Curve: Click on the curve to add an anchor point and drag up/down or enter numeric values to adjust the tonality of the image. The Corner option produces a sharp change in the angle of the curve, which is generally not desirable. The button to the right of Corner resets the curve.
Switching the Mode menu to 32-bit color restricts you to adjusting the preview — anything else will be done in Photoshop after you click Merge to HDR Pro’s OK button. (The entire expanded tonal range is still in the 32-bit image, it’s just the preview that you’re adjusting.) Using options other than Local Adaptation in 16-bit mode give you less (or no) control over the conversion from 32-bit color.
16-bit mode’s Exposure and Gamma option gives you a pair of sliders to control the overall tonal range and the contrast between shadows and highlights, while the Highlight Compression and Equalize Histogram options give you no control over the appearance of the image. In 32-bit mode, you have a simple slider to adjust the preview.
Note that 16-bit and 8-bit offer the same options, but it's not recommended converting from 32-bit to 8-bit in Merge to HDR Pro. If you need an 8-bit version of the image, work in16-bit, and then after perfecting the image in Photoshop and saving as 16-bit, use the Image→Mode→8-Bits/Channel command to convert and use Save As (or Save for Web) to save the 8-bit copy.
Remember that when the changes you make in Merge to HDR’s 16-bit mode are finalized, the unused parts of the 32-bit tonal range are discarded. Working in 16-bit mode in Merge to HDR Pro can be convenient, but you can also stay in 32-bit mode, open into Photoshop with the OK button, save the 32-bit image, and then do all the adjusting available in Merge to HDR Pro — and much more — in Photoshop.
Want to fine-tune or change the image sometime down the road? Sure, why not? Simply reopen the saved 32-bit image and readjust, paint, filter, whatever, and then save again. Need a 16-bit copy to share or print? Save first as 32-bit, adjust, and then use Save As to create the 16-bit copy.