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2. Basics of Image Processing

## 2.3 Layers

### 2.3.1 Introduction

Layers are used in modern image processing to simplify work. Layers can be thought of as transparent foils, each containing a part of the resulting picture.

This technique has several advantages. A layer can always be moved without modifying the rest of the picture and painting on a layer doesn’t affect other layers.

But layers offer more than foils in conventional work. A layer laying on another can be made transparent in nearly infinitely variable steps. It is even possible that an underlying layer is not simply replaced but combined in various ways by using a display mode.

There are several kinds of layer: image layers, vector layers, text layers and groups. All kind of layers have advantages and disadvantages, therefore it is usually efficient to use not only one kind in a picture. For example it is possible to set a text layer on an image layer. Possibly it is nice to have a colored rectangle, which is a vector layer, behind the text to make it more readable:

By using various kinds of layers it is possible to do more than simple image processing. You can rather accomplish all kind of design work like greeting cards, business cards, CD labels and much more.