Adobe Photoshop CS5 for Photographers - Martin Evening [153]
Mask adjustments
The one time when you may find it useful to use the legacy style Brightness/Contrast image adjustment is when you wish to edit the contents of an image layer mask. The crudeness of the Brightness and Contrast adjustments can actually be beneficial when you wish to force the highlight areas of a mask to go to white and the shadow areas to go black.
1.
This before version shows a photograph that needed a Brightness/Contrast adjustment to brighten the picture.
2.
Here is the same photograph after I had applied a Brightness/Contrast adjustment (with the Use Legacy box unchecked). Notice how the histogram in the corrected version preserved the full tonal range from the shadows to the highlights.
Correcting shadow and highlight detail
The Shadows/Highlights image adjustment (Figure 5.42) can be used to reveal more detail in either the shadow or highlight areas of a picture. It is a great image adjustment tool to use whenever you need to expand image tones that are too compressed in the original image, but it can be used to perform wonders on most photos and not just those where you desperately need to recover shadow or highlight detail.
Figure 5.42 The Shadows/Highlights adjustment dialog is shown here in Basic mode. Checking the Show More Options box will reveal the Advanced mode dialog shown in Figure 5.43.
The Shadows/Highlights image adjustment tool makes adaptive adjustments to an image, and it works in much the same way as our eyes do when they automatically compensate and adjust to the amount of light illuminating a subject. Essentially, the Shadows/Highlights adjustment works by looking at the neighboring pixels in an image and makes a compensating adjustment based on the average pixel values within a given radius. In Advanced mode, the Shadows/Highlights dialog provides additional controls that allow you to make the following fine-tuning adjustments (Figure 5.43).
Figure 5.43 In the Show More Options mode, the Shadows/Highlights dialog contains a comprehensive range of controls. I would advise you to always leave the ‘Show More Options’ box checked so that you have this as the default mode for making Shadows/Highlights adjustments.
Amount
This is an easy one to get to get to grips with. The default Amount setting applies a 35% amount to the Shadows. You can increase or decrease this to achieve the desired amount of highlight or shadow correction. I find the default setting does tend to be rather annoying, so I usually try setting the slider to a lower amount, or zero, and click on the Save As Defaults button to set this as the new default setting for each time I open Shadows/Highlights.
Tonal Width
The Tonal Width determines the tonal range of pixel values that will be affected by the Amount setting. A low Tonal Width setting narrows the adjustment to the darkest or lightest pixels only. As the Tonal Width is increased the adjustment spreads to affect more of the midtone pixels as well (see the example shown in Figure 5.44).
Figure 5.44 The Tonal Width slider determines the range of levels the Shadows/Highlights adjustment is applied to. For example, if the Shadow adjustment Tonal Range is set to 50, then only the pixels which fall within the darkest range from level 0 to level 50 will be adjusted (such as the deep shadows in this photograph).
Radius
The Radius setting governs the pixel width of the area that is analyzed when making an adaptive correction. To explain this, let's concentrate on what would happen when making a shadow correction. If the Shadow Radius is set to zero, the result is a very flat-looking image. You can increase the Amount to lighten the shadows and restrict the Tonal Width, but if the Radius is low or is set to zero, Photoshop has very little ‘neighbor pixel’ information to work with when trying to calculate the average luminance of the neighboring pixels. So if the sample Radius is too small, the midtones also become lightened. If the Radius setting is set too high, this has the effect of averaging all