Photoshop® CS3 Channels and Masks Bible

Chapter 1. Building Images

IN THIS CHAPTER

• Distinguishing between vector and raster

• Understanding bit depth

• Understanding file formats

• Determining resolution and size Using the Crop tool

• Working with layers

• Introducing masks

Photoshop image is like a building. The color channels are the foundation that ultimately determines the image's core structure, just as the pixels are the building blocks of its visual elements. It may contain layers that are its multiple floors and it can have masks that act as windows.

Just as there are many different ways to construct a building, in Photoshop, the choices you make can also dramatically affect how an image appears, how it is edited, and ultimately how it is output. This chapter analyzes the elements that constitute the structure of a Photoshop image. It addresses how the elements are assembled and accessed and defines important termi-nology. Furthermore, this chapter demonstrates how to utilize these key fea-tures in the creation and manipulation of an image.

Distinguishing Between Vector and Raster

Two fundamentally different methods are used to create still images. Vector graphics are objects composed of mathematically defined points, curves, and shapes called objects. Raster images use a grid of colored squares, called pixels, to render variations of color.

Vector graphics

Vector graphics are composed of paths and points that define their shapes. The vector tools, such as the Pen tools, the Shape tools, and the Type tool are used to draw these objects. ...