Page 21 - Enhancing CAD Drawings with Photoshop

4386.book Page 4 Monday, November 15, 2004 3:27 PM
4 CHAPTER 1 THE BASICS

NOTE AutoCAD objects are independent of resolution.
On the other hand, data that represents color is more difficult to manipulate using math. In point
of fact, colors are ultimately represented by numbers on a computer. However, the way color data is
stored and manipulated is far less efficient than the way numerical data is stored and manipulated
with math. Let’s take a look at Photoshop to see how it fundamentally handles data.
1. Launch Photoshop.
2. Choose File New to open the New dialog box (see Figure 1.3). Click the Width and Height
drop-down lists and change the measurement to pixels. Type 600 in the Width text box, and
type 450 in the Height text box. Set the Resolution to 72 pixels/inch, and choose White from the
Background Contents drop-down list. Click OK to create a new image document with these
settings.
Figure 1.3
Creating a new Photo-
shop document

The process of creating a new document shows how Photoshop works; it stores data as pixels
(“picture elements” that are tiny squares of color). You have to choose exactly how many pix-
els you want to work with right from the beginning. The resolution is the pixel density, or how
many pixels appear per unit length.

3. Click and hold the Rectangle icon in the toolbox to display the hidden tools. Select the Line tool.

4. The Options bar is at the top of the interface (see Figure 1.4) and displays context-sensitive
information for many of the tools in the toolbox.
Click the third button from the left, Fill pixels, to directly create pixels using the tools shown
on the right. (The Line tool is selected.)