Photo Color Correction
Adobe Photoshop Tutorials
Adjustment Layers
Adjustment Layers are Photoshop's solution for photo color problems. They are the tools for color management and the control panel for basic, intermediate, and advanced photo color correction.
History
Photoshop 1.0, the first version of Photoshop, did not have Adjustment Layers. In fact the first few versions of Photoshop did not have any layers, either for objects or color adjustments. Layers for color were finally introduced in Photoshop 4.0.
In 1998, for Photoshop's tenth Birthday, Mark Allison looked back at the history of Photoshop, explaining its development, and noted Photoshop 4 brought the addition of "adjustment layers for colour correction."
Deke McClelland, industry professional and best-selling author, said adjustment layers were Photoshop 4's "most important new feature." (Photoshop 4 Bible for Windows 95, p. 680)
Photo color correction, to the extent it was possible in the early editions of Photoshop, was permanent. Every change, either great or small, was final, except for the Undo. That is what it was like without layers. Once you had saved your work and shut down the computer, that was it.
Color adjustments can still be done in Photoshop without Adjustment Layers, but it is living in the past. There is virtually no advantage in not using adjustment layers. They take up little file space and they allow total flexibility for future editing. They do not change the original image.
Definition
Introducing adjustment layers in the Photoshop 4.0 Bible, Deke McClelland said:
- New to Photoshop 4, adjustment layers are layers that contain mathematical color correction information.
Description
Adjustment layers, like the name suggests, are layers for adjustments. They are used for the adjustment of both color and tone. They are Color Adjustment Layers.
Adjustment layers are like the other layers in Photoshop. They show up in the Layers Palette, and they can be named and moved the same way as other layers.
New
There are three ways to bring up the Adjustment Layers for color correction:
1. Layer > New > Adjustment Layer
2. Ctrl-New Layer (on the base of the Layers Palette)
3. Click on the right arrow (at the top of the Layers Palette), then select New Adjustment Layer
Position
Adjustment layers must be positioned above the photo; they affect nothing underneath them. They can affect only the photo over which they are placed. They can be grouped with object layers.
One adjustment layer can be added over a photo layer, or many adjustment layers can be used for the same photo. Copies of adjustment layers can be used for the same image.
An unlimited number of adjustment layers can be stacked on top of one photo. Typically the most Adjustment Layers one photo would need would be no more than one of each of the six primary color adjustment layers:
Levels, Curves, Brightness/Contrast, Color Balance, Hue/Saturation, and Selective Color Options.
Order
The order of adjustment layers is usually not significant. It is possible to start with any adjustment layer, either Levels, Curves, Selective Color Options, or any of the others.
There is no required order but the important thing is to make sure the layer order is not changed by mistake or to assume any changes in adjustment layer order will yield the same results. If several adjustment layers are used and the order is reversed, for example, it can yield different results.
A good habit is to stack Adjustment Layers in the default order, i.e., the order in which Photoshop lists them in the New Adjustment Layer control panel (see below); then you always know where they should be if one layer is accidentally moved.
Layer Masks
An adjustment layer is a color filter and a layer mask in one layer. It filters color and it can be filled to change the color of select parts of a photo, instead of the entire image. Like layer masks (Layer > Add Layer Mask), adjustment layers offer full range, from one pixel to the entire picture.
Opacity
Just like photo layers, the opacity of adjustment layers can be adjusted from 0 to 100%. Simply type a single number or two numbers. Pressing '5' sets the layer opacity to 50%; '1' to 10%; and '0' brings it back to the default setting (100%).
Rarely necessary but still an option is setting the opacity to a number more specific than a multiple of 10, e.g., 75%. The two numbers must be typed fairly quickly. If you type '75' quickly, the opacity will change to 75%; if you type them too slowly, it will change to 70% ('7'); then 50% ('5').
Saving
Some adjustment layers can be saved as independent files so they can be imported into other photo files. This makes it possible to do color correction on many photos which have the exact same color problem.
Where the Save/Load options are available, they are on the right side of the adjustment layer dialog box.
The adjustment layers which can be saved are Levels, Curves, Hue/Saturation, Selective Color Options, and Channel Mixer; the ones which cannot be saved are Brightness/Contrast, Color Balance, Invert, and Posterize.
Actions
Similar to saving adjustment layers as files, adjustment layers can be saved as Actions.
Reset
All adjustment layers (except Invert) can be reset. Hold down the Alt key and the dialog box will change, adding a Reset box where it used to be Cancel.
Reset will reset every part of the adjustment layer. If you are in the Red section of Curves, for example, and click Reset, it will reset everything on that adjustment layer including Red, i.e., RGB, Red, Green, and Blue.
Preview
Photoshop lets you preview potential color corrections. In each adjustment layer there is a Preview box which has to be checked. You can toggle the preview box on and off.
View Changes
In the layers palette, all the adjustment layers can toggled on and off, too, with one click. If you hold down the Alt key and click on the eye icon of one layer, such as the photo layer, which is getting the color corrections, it turns off every other layer.
In this way you can view changes, compare the before and after pictures instantly. You can monitor progress in the correction process.
Click the same place on the palette one more time, and it turns every layer back on.
All
There are 10 different adjustment layers:
- Levels
- Curves
- Brightness/Contrast
- Color Balance
- Hue/Saturation
- Selective Color
- Channel Mixer
- Invert
- Threshold
- Posterize