Exposure and Contrast

The Exposure and Brightness tools in previous versions of Lightroom have essentially been combined into a single control in PV2012. Exposure is meant to be used to set midtones to a desired level of, yes brightness. Exposure adjustments appear to have gentler roll-off towards the highlight and shadow end in PV2012, making for a less contrasty transition away from the midtones.

Of course, precise control over contrast can be found in the Contrast slider, which works as you'd expect. Once overall image exposure has been set to a pleasing value, use the Contrast slider to increase or decrease the luminance difference between pixels brighter than a midtone and pixels darker than a midtone.

The Exposure and Contrast sliders exist at the top of the editing panel for good reason. Taken as a pair, these tools perform the bulk of the heavy lifting in traditional image edits. The results can be significant and in many instances you may find they get you very close to a finished image.

Here we see the image at default settings of 0 for both Exposure and Contrast. The image appears a bit dull and flat in addition to being a bit too dark.
Adjusting the Exposure slider to +.40 brightens the car to a pleasing degree. The image however lacks sufficient contrast.
Adding a Contrast adjustment of +50 provides greater separation between brighter and darker tones in the image.There's still work to be done on the sky area for example, but this is a very good start considering only two slider adjustments have been carried out.

One notable addition to Lightroom 4 is that its highlight recovery algorithms are now automatically enabled in the image processing engine. When compared at their default settings you may well find that with raw files PV2012 consistently reduces highlight clipping to a greater degree than its predecessor, PV2010.

In these before/after comparisons, you can see that PV2012 versions (on the right in each pair) display significantly less highlight clipping (indicated in red) than images processed using PV2010. All images are shown at the default settings of each process version.

Highlights and Shadows

While a negative Exposure value can help reduce highlight clipping, up to a point, the Highlights slider is the primary means with which to perform highlight recovery. While it is, in principle, the most direct substitute for Lightroom 3's Recovery tool, Highlights - in addition to moving in both positive and negative directions - has a more aggressive parameter range and should be used much more conservatively. A little bit goes a long way here. It's also worth pointing out that when all three RGB channels are clipped in the initial capture, all that any of these tools can do is make white pixels less white. To recover any visible detail, the image must contain real data in at least one RGB channel.

Of course the Highlights slider is not just a tool for fixing blown out details. You can use it to even out tones in directional lighting scenarios and even push bright tones closer to maximum white, examples of which you'll see in the image comparison that follows.

The Shadows slider works on the opposite end of the tonal spectrum and is used to control the luminance of pixels that photographers generally think of as being in shadow. A negative Shadows value will darken these pixels while having as little effect as possible on the absolute darkest pixels of the image. In short, you get the ability to set rich, satisfying dark tones for your image without clipping large amounts of image detail to maximum black.

In the example below we'll compare a before and after set of images using the Highlights and Shadows sliders in addition to the Exposure and Contrast controls we looked at previously.

The original image (left) appears a bit flat. I started by making an Exposure adjustment of +.20 and moving the Contrast slider to +15. Overall brightness and contrast is improved (center) but this leads to areas of the face being too bright. Moving the Highlights slider to -25 evens out the facial tones (right) and I've opted for heavier tones in the hair by setting Shadows to a value of -17. I also used an Adjustment brush with the Highlights slider at -60 and painted over the background, making it a shade of white instead of gray.

Whites and Blacks

The Whites and Blacks sliders address the far ends of the histogram, controlling the brightest and darkest pixels respectively. They have the most constricted tonal range of any of the previous sliders and are meant to be used to set the endpoints of your image's dynamic range.

These tools are most effective when used after the general tonal relationships in the image have been established with the sliders we've just discussed. Again, note their position in the tool layout. Move the Whites slider to the right if your aim is to move the image's brightest pixels closer to pure white. When you move the slider to the left you are effectively creating a more gently-sloped roll-off from the brightest pixels in the image to those that are almost as bright.

The Blacks slider performs a similar task with the image's darkest pixels. A negative move can clip pixels to maximum black, giving a sense of deep rich shadows. The trick of course is to limit the adjustment so that important shadow detail is not obscured.

At the default settings the original
image appears a bit flat and dull.
An Exposure of +.10 brightens the
image slightly. A Contrast of +30
gives better separation between
the sky and the cross.
A Shadows value of -60 darkens
areas along the top of the fence.
With the tonal relationships now in
place the Whites slider is set to
+10 and the Blacks value is set
to -55. This extends the image's
tonal range for a more pleasing,
dramatic result.

Clarity

While the functionality of the Clarity slider remains the same - to adjust midtone contrast - the algorithms behind it have been updated. The Lightroom 4 version can be used more aggressively when set to positive values without leading to noticeable halos along high contrast edges.

Localized adjustments

Lightroom's localized adjustment tools, the Adjustment Brush and Graduated Filter, get some new options. In Lightroom 4 you can selectively adjust WB to correct for mixed lighting situations, apply noise reduction only where it is needed and remove moiré patterns.

In addition to the revamped Basic panel controls, you can now apply localized corrections using the Temparature, Tint, Noise and Moiré sliders.

RGB Point Curves

In Lightroom 4's Tone Curve panel you can make Point Curve edits to individual RGB channels, a task that until now required a trip to Photoshop. Click the 'Edit Point Curve' icon at the lower right of the histogram window  then click the panel's Channel menu and select the curve you wish to edit. The Targeted Adjustment Tool (TAT) can be applied with each channel. With precise control over individual RGB curves you can fine-tune color balance, convert color negatives to positives images (or vice versa) or apply any number of creative color techniques.

You can mimic creative darkroom effects like cross-processing by manipulating individual RGB curves.

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