Adjustment Layers

Adjustment Layers

Adjustment layers rock! They are the most flexible way to adjust an image, since you can continue to tweak the effect by double-clicking on the adjustment layer. For many of the adjustments (see below), you can either go to the Image menu, under Adjustments, and select an adjustment method, or add an adjustment layer for the equivalent effect from the Layers palette. The difference is that using the Image>Adjustments menu is a much more "permanent" method, since you are altering the pixels in the image.

Here's a simple example, exaggerated to make the point more obvious. In the first scenario, I pressed Command-L (PC: Control-L) to open the Levels dialog. After making an adjustmentdeliberately overdone in this caseI clicked OK and saved the document.

DAVE CROSS

If I later decide to work on the document, and open Levels again, the Histogram makes it pretty clear that it would be very difficult to make any further changes to "correct" the poor initial adjustment.

I always thought that Adobe could help us out a little bit when you're faced with a histogram like this one by changing the Levels dialog to look more like this:

Contrast that with using a Levels adjustment layer: I still made a rather poor over-adjustment, but this time I have a safety net. Even after saving the documentwithout flatteningI can continue to make adjustments by double-clicking on the adjustment layer.

This time, instead of the nasty-looking histogram filled with big gaps, the Levels adjustment layer dialog opens just as I left it, ready to be tweaked (or in this case, rescued).

Here are the adjustment layers you can add from the Layers palette:

Levels

Curves

Color Balance

Brightness/Contrast

Hue/Saturation

Channel Mixer

Selective Color

Gradient Map

Photo Filter

Invert

Threshold

Posterize

That leaves a bunch of other adjustments that cannot be applied as adjustment layers:

Auto Levels

Auto Contrast

Auto Color

Desaturate

Match Color

Replace Color

Selective Color

Shadow/Highlight

Exposure

Variations

What to Do When You Can't Use Adjustment Layers

To create the rough equivalent of an adjustment layer, duplicate the Background layer, and then apply one of the non-layer adjustments. Press Command-J (PC: Control-J) to make a copy of the Background (or whatever layer it is you want to affect), then apply the adjustment to the copied layer. Although you cannot double-click to edit the adjustment, you do have a little more control over the effect. You could lower the Opacity of the duplicated layer to lessen the effect (by letting the original Background show through), or you could delete the duplicated layer and start over, since the Background layer is untouched.

Faking "Filter" Layers

Okay, so there's no such thing as a Filter layer (that would be cool though, wouldn't it?). Instead, you can create a more flexible version of a filterand change the effectby duplicating the layer that you want to apply the filter to. Then change the Opacity to lessen the effect of the filter, or choose a blend mode to alter the look. In addition, you can add a layer mask to the filtered layer to restrict the effect to a portion of the layer. Take a look at these examples that show how you can lessen the effect of a filter, or get quite a different look.

Here, the Gaussian Blur filter (Filter>Blur) was applied to the copied background, using a setting of 12 pixels.

Original

DAVE CROSS

After Gaussian Blur

Here the Opacity is lowered :

75%

50%

Here's to 100%, using different blend modes:

Multiply

Lighten

Vivid Light

Remember, you can always get back to the original Background simply by dragging the copied version to the Trash icon.



Photoshop CS2 Help Desk Book
The Photoshop CS2 Help Desk Book
ISBN: 0321337042
EAN: 2147483647
Year: 2006
Pages: 225
Authors: Dave Cross

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