Adobe Photoshop CS5 for Photographers - Martin Evening [151]
Easier blend mode access
One of the main benefits of the Adjustment layers approach is that you can switch easily between editing the adjustment controls in the Adjustments panel and adjusting the layer opacity and blend mode settings.
This is also where using adjustment layers can come in useful, because you can easily switch the blend modes for any adjustment layer. In the example shown opposite, a Curves adjustment was used to add more contrast to this sunset view of a mountain. When this adjustment was applied in the Normal mode (as shown in Step 1), the color saturation was increased. However, if the same Curves adjustment was applied using a Luminosity blend mode, there was an increase in contrast but without the increase in color saturation. Incidentally, I quite often use the Luminosity blend mode whenever I add a Levels or Curves adjustment layer to an image, especially if the image has already been optimized for color. This is because whenever I add localized corrections I usually don't want these adjustments to further affect the saturation of the image. Similarly, if you are applying an image adjustment (such as Curves) to alter the colors in a photo, you will want the adjustment to target the colors only and leave the luminance values as they are. So whenever you make a color correction using, say, Levels, Curves, Hue/Saturation, or any other method, it is often a good idea to change the adjustment layer blend mode to Color.
If you happen to prefer the direct adjustment method, you can always go to the Edit menu after applying a Curves adjustment (or any other adjustment such as a brush stroke or a filter) and choose ‘Fade Curves…’ ( ). This opens the Fade dialog shown in Figure 5.37 where you can change the blend mode of any adjustment as well as fade the opacity.
Figure 5.37 The Edit Fade dialog.
1.
When you increase the contrast in an image using a Curves adjustment, you will also end up increasing the color saturation. Sometimes this can produce a desirable result because some photographs may look better when you boost the saturation.
2.
In this example I applied the same Curves adjustment as was applied in Step 1, but I changed the layer blend mode to Luminosity. This effectively allowed me to increase the contrast in the original scene, but without increasing the color saturation.
Curve presets
At the top of the Curves dialog you will see a Preset menu (Figure 5.38). This contains a number of custom Curves presets that are shipped with the program, plus any Curves presets that you have saved recently. The standard Curves presets offer some fairly straightforward settings. For example, you can use these to make an image lighter or darker, or apply different contrast curve shapes. These presets might be useful as starting point settings and you can run through the Presets menu selecting the various curve settings just to see how they will affect the look of an image. Some of the other Curves settings ambitiously aim to apply a cross- process style effect or convert a color negative scan into a positive image. In my opinion, these settings are a bit hit or miss. If you want to take a color negative scan and make it into a positive, you would need to create special custom Curves settings for each different type of color negative emulsion. In all honesty, if you are going to scan color negatives, then you are probably going to be better off letting the scanner software do the conversion for you.
1.
If you use Photoshop to convert a color negative to make a positive, you could try selecting the Color Negative preset shown in Figure 5.38, but this is unlikely to produce a successful conversion.
Figure 5.38 Here is a view of the Curves dialog, showing the Custom Curves menu. Note that if you create a manual Curves setting and then select a preset, the applied setting overwrites