Highlights and Shadows
The Highlights and Shadows sliders work identically on either side of the tonal range and offer far more scope as to what can be done at the image processing stage. With Process 2003/2010 the Recovery slider could only be used to darken the highlights and Fill Light could only lighten the shadows. With these new sliders you can both lighten or darken. For example, you can use a negative Highlights adjustment to restore more highlight detail, or a positive adjustment to deliberately blow out the highlights. As I mentioned earlier, these sliders work symmetrically so that unit adjustments have equal effect and only affect the tone regions either side of the midtone point. To be clear, the range of these sliders does extend beyond the midtone point, but the greatest effect is concentrated in the highlight tones for the Highlights slider and the shadow tones for the Shadows slider. Adjustments in the +/– 50% range will have a normal type effect when lightening or darkening. As you apply adjustments greater than this the lightening or darkening adjustments are applied via a halo mask. This is a special technique that is used in HDR tone mapping to help compress the tonal range of an HDR image. The problem when using this type of technique is that as you apply a strong effect, the halos become more noticeable (though some people seem to quite like this kind of effect). With Lightroom 4, the goal has been to make the halo mask as unobtrusive as possible. When pushed to extremes it can be possible to detect a halo, but for the most part it’s quite well disguised.
Typically, after setting the Exposure and Contrast you would then use the Highlights and Shadows sliders to enhance the highlight and shadow areas as necessary. Here again, it is possible to hold down the key to reveal a Threshold analysis view as you adjust the Highlights and Shadows sliders. There may be some potential value in doing this at this stage, but I would urge you to mainly judge the appearance of the preview image for the nuances that can be achieved in the shadow and highlight regions rather than what a threshold analysis is telling you. The Highlights and Shadows controls also inform the whites and blacks how much tonal compression or expansion has been applied and the Whites and Blacks controls adjust their ranges automatically taking this into account.
Figure 4.30 The Auto tone button (circled) can be used to apply an instant auto correction.