Working with Layers

	Layers are a concept used in many advanced graphics programs to help users manipulate different objects in their projects. The concept is actually a metaphor from cel animation, in which layer upon layer of transparent acetate were placed on top of one another. Each layer had a small part of the drawing on it, like an eye or a leg. This way, in order to animate a pair of eyes, the animators only needed to re-draw the eyes, instead of the whole face. In graphics programs, layers work the same way. Instead of having to manipulate the entire image with each change, you can alter small parts of it until it is just right.
Man in the Rain image	Layers of the Rain image

Layers are a concept used in many advanced graphics programs to help users manipulate different objects in their projects.

The concept is actually a metaphor from cel animation, in which layer upon layer of transparent acetate were placed on top of one another. Each layer had a small part of the drawing on it, like an eye or a leg. This way, in order to animate a pair of eyes, the animators only needed to re-draw the eyes, instead of the whole face.

In graphics programs, layers work the same way. Instead of having to manipulate the entire image with each change, you can alter small parts of it until it is just right.

Man in the Rain image

Layers of the Rain image

Manipulating Layers

While each program has its own layer controls, most share some basic functions: Image of layer display from Photoshop 6 for MAC

Layer order - layers high on the list are "above" layers lower on the list. Objects on higher layers appear to be on top of objects on lower layers.
Visibility - layers can be made visible or invisible by clicking this icon (usually an eye or a check mark.)
Alterability - layers can be "locked" against accidental altering. With most programs locking layers also prevents you from inadvertently selecting them.
Selected Layers - With most programs, the layer that is selected is the one on which the changes you're making takes place. In the image to the left, layer 2 is selected.
Opacity - most programs that use layers allow you to modulate the opacity/transparency levels of your layers. This allows you to "blend" images together.

You can usually find these layer controls in a special "Layers" window or panel tab. Since these functions occur in most graphics programs that use layers, you can be sure learning how to use them will be useful.

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