Tweaking Exposure and Contrast
At this point, we can brighten the shot a little bit (globally) and enhance the contrast before we look at how we can enhance the localized contrast in this shot. To do this, we’ll use a combination of Exposure, Contrast, and Curves (with the new Per Channel point curve enhancement).
For this shot I boosted the Exposure by about .25 to brighten the details on the boat and foreground. In Lightroom 4, the Exposure control targets only the “center 50%” of tones.Applying moderate adjustments to the Exposure value will often do a good job of brightening or darkening, without making pronounced changes to the darkest and lightest tones. Keep in mind this was shot on the middle of a fall morning, under overcast skies, so we want to maintain the realism of that environment. Notice that the cloud details are preserved despite the Exposure boost, and no additional clipping is seen in the Histogram (Figure 5).
Figure 5: The Exposure control in Lightroom 4 works more like traditional exposure controls in Photoshop and other applications, allowing you to focus on the mid-tones.
Next we can use the Contrast control (which operates as it always has) to “stretch” our Histogram values a bit. For this image, a value of roughly 40 correctly sets the darker materials on the boat closer to a black appearance, while allowing the brightened water details to remain mostly intact (Figure 6).
Figure 6: Use the Contrast control as you normally would to enhance the differences between lighter and darker regions in the photo.
One last thing we can do to enhance the contrast is use the new Per Channel contrast in Lightroom’s Tone Curve panel (via the point curve mode). Combined with a new Channel pop-up menu (located just below the curves widget), the point curve’s Targeted Adjustment Tool will allow us --just as we’ve always been able to do in Photoshop-- to brighten or darken the red, green or blue tones in isolation, throughout the image. For this shot, I wanted to cut through some of the blue cast caused by the cloudy weather, while accentuating the warmer tones on the dock.
To do this I selected the Point Curve mode by clicking the small button (bottom-right portion of the panel). Then under Channel I chose the blue channel option. Next I clicked on the Targeted Adjustment widget (top-left portion of the panel), then clicked and slowly dragged downward over the brightest parts of the boat’s cabin. This mitigated the blue cast in the brighter areas of the shot. From there, you can either continue to place points by clicking and dragging on the image preview, or you can add points by directly clicking and dragging on the curve itself (Figure 7).
Figure 7: Per Channel Point Curves allow you to make adjustments in Lightroom 4 that were only possible previously in Photoshop’s Curve adjustment.
For the red channel I followed a similar process, manually boosting the mid-tone areas while attempting to leave the brighter- and darker-toned areas in their original state. Notice now that the hull of the boat still has a whitish appearance, while the dock is warmer. We even have an interesting “tinted reflection” effect from the clouds, visible on the windshield of the boat. We’ve also created a slightly warm “color cast” on the side of the boat nearest the dock, which is what we’d expect to see (Figure 8).
Figure 8: The boat, dock and clouds have an enhanced color contrast after using Per Channel Point Curves in Lightroom 4.