One of the most important features of Photoshop is the ability to work on images using Layers. Different parts of an image can be changed independently on separate layers, which are controlled through the Layers palette and the Layers menu.

This is used to control and organize layers. When an image is opened, a small icon of the photograph appears. This is titled Background Layer. From here, new or duplicate layers can be added on top of the layer. The active layer (the layer being worked on) is highlighted in blue. To move between layers, simply click on the relevant icon or name.

It is a good idea to copy the background layer to work on, and leave the original untouched. To copy a layer, drag it to the copy icon. If the work done is unsatisfactory, drag the copied layer to the trashcan to delete it. Then make a new duplicate to work on.

A copy layer was made of the photograph below, and then a noise filter applied to add the textural effect of film grain. Different modes of dissolve were used to achieve different blending effects. (Photograph by Huw Walters.)

The copy icon can also be used to make an empty layer, which is useful for importing other images or adding text. Click on the icon once and a new layer will be created.

As more layers are added, especially if they are duplicate layers, give each one a different name so that you can easily identify which is which. Simply click twice on the layer name to select it and then type in a new title.

Adjustment Layers are another method for using some of the main controls for contrast and color, such as Levels and Color Balance. However, unlike applying changes directly to the image, an Adjustment Layer can be selected and changed at any time, or it can be deleted if not required. To open an Adjustment Layer, make sure the correct layer is active and highlighted, then click on the Adjustment Layer icon above, or select the relevant control from the New Adjustment Layer sub menu in the Layers menu.

These are similar to Adjustment Layers but, instead, fill the image with either a single tone, a gradient, or a pattern. Once in place, they can be dissolved with the open layer to reduce the effect.

Each layer in the Layers palette has an Eye icon, which indicates whether or not it is visible (although a layer may be obscured by another layer even if it is “visible”). Click on the icon to hide the layer. Click on it again to reveal it.

As each new layer is added, it is placed on top of the stack of other layers. To change their order, simply drag a layer and drop it in the desired position in the Layers Palette.

To prevent making any accidental changes to a Layer, click on the Lock icon. Click on it again to unlock it so that changes can be made or it can be deleted.

As layers are stacked on top of each other, we can use different Blending Modes to merge them together. If set to the default mode (Normal), the top layer will hide the one below it. By reducing the level of the Opacity slider, the lower one starts to appear. Thus, a particular effect or filter applied to a copy layer could then be diffused with the original to fine-tune the effect. There is a comprehensive list of more than 20 different modes to use, including darken, lighten, multiply, and overlay.

Darken Areas of the top layer lighter than the same area on the underneath layer will show the darker tones of the bottom layer. Lighten This is the opposite of Darken mode. Darker areas in the top layer will show the bottom layer underneath.

Multiply This shows two images layered together at 100 percent opacity. Both will be visible, but they will appear darker. The top layer retains its transparency, so the layer underneath can still be seen. This is useful for combining black-and-white illustrations with color photos, as just the black will be seen over the image underneath. Overlay This merges the top layer onto the bottom, but keeps the highlights and shadows of the bottom layer.

Though it is possible to make hundreds of layers on the same image, each new layer will increase the file size and use up more RAM from the desktop. There are three different methods to permanently merge and blend layers in the Layers Menu, saving RAM:

Use this to blend all the layers together, so that only one remains, becoming the new Background Layer. Hidden layers will be discarded when this is done.

Use this to merge the active layer with the layer underneath.

Use this to merge all open layers. Hidden layers will be kept intact.

Using Layers becomes an intuitive way of working, and most images will benefit from changes being made to duplicate, copy, or adjustment layers instead of the original background layer. The more you use Layers, the more you can learn to control your images.

Below, layers were used to blend together this image with a copy layer, filtered to resemble a charcoal drawing to give a softer effect. (Photograph by Huw Walters.)

Providing the resolution is the same, you can export an active layer from one image to another by selecting Duplicate Layer. The Destination will be shown as being the same image, though the Document drop-down menu will also contain any other currently open image. Press OK and the layer will be copied and transferred.

To move a selection from one image to another, use the Move tool to drag it and drop it onto the other image. It will then open as a new layer. Alternatively, the Select shortcuts can be used to copy, cut, or paste (Ctrl/Command X, C, or V) selections from one image to another.

When the text tool is used, it opens as a new layer. Separate pieces of text will then create separate layers, which can be merged together. Type effects can also be added from the Styles and Effects palette.

When layers are dissolved together, it can be effective to remove parts of the top layer to show the layer below. This can be done with a Brush set to clear. Whole areas can be selected and then cut out by pressing Ctrl/Command X. This technique has many uses, such as brightening clouds in a sky. Place a copy layer that has been brightened underneath a normal layer. Then, with a soft brush set to perhaps 25 percent Opacity, brush away the darker clouds on the top layer to reveal the brighter ones below.

I liked the cool tone of the hill on the original shot, below left, but not the green background. The red was increased on a copy layer and then these were blended together using a Darken dissolve to keep the shadow tones of the upper, original layer. (Photograph by Huw Walters.)