Remapping Picture Tones
For this example, we have a photograph that illustrates the common problem of a scene containing tones that are both too bright and too dark to be captured by a single exposure. As a starting point I first applied a Lens Profile Correction via the Lens Corrections panel. This had two minor effects: 1) It smoothed out some geometric distortion due to the curvature of the lens elements, and 2) it shifted the Histogram values slightly to the right (brightening the uncorrected image a small amount).
Using the new Basic panel controls in ACR 7, the first tone mapping correction we need to make is to recover detail in the over-exposed cloud regions (above the buildings but below the top of the frame). Since this is a sunset photo and most of the data is found in the brighter half of the Histogram to start, only a minor change to the Exposure setting is needed. Reducing the Exposure to a value of -.25 “ created the correct overall brightness, while also restoring some of the highlight details.
To recover the rest of the highlight details, we can move the Highlights control well left, using a value of -90 in this case. This brings back a substantial amount of detail--and also color-- in the central part of the image. Figure 2 shows the improvements made with just these two changes.
Figure 2 The Highlights control in ACR 7 is extremely useful for recovering lost highlight details from over-exposed areas in your pictures.
Next we need to perform the corresponding detail recovery in the shadow areas. Specifically, the trees and details on the island between the viewer and the skyline should not be pure black. To do this I zoomed in to get a closer look, then boosted the Shadows to a value of +80. Notice (in Figure 3) how much more detail is visible and notice the distribution of tones in the Histogram: the right side of the preview shows the original detail overlaid onto the edited screenshot.
Figure 3 The Shadows control in ACR 7 does a great job of revealing detail.
Figure 4 zooms back out so we can see much more of the photograph. It’s hard to believe just three adjustments to this formerly “over-and-under-exposed shot,” and we already have a much more usable result!
Figure 4 Sometimes all you need are a couple of Highlights and Shadows adjustments to dramatically improve a photograph.
However, this is just the start. Let’s keep going! The next task is to stretch the very brightest and darkest tones in the Histogram back to the edge (effectively setting the brightest and darkest points in the image without clipping them), to enhance our overall contrast. We can do this by using the Whites and Blacks settings, respectively.
For the Whites I nudged the slider out to a value of about +14, and for the Blacks setting I had to shift the slider left to a value of -21. This ensured that some inky black tones would remain in the shot, further enhancing both the realism and the dynamic range of the visible tones. Figure 5 shows a slightly zoomed in version of our shot. Notice the Histogram as compared to Figure 1; details have been recovered and tones shifted, but the global brightness and contrast remain true to the original scene.
Figure 5 The Whites and Blacks controls help to “re-map” the brightest and darkest tones (respectively) to the edges of the Histogram, improving the range of tones and overall contrast.