Customizable rulers, along the top and left sides of the document window, can help you scale and position Photoshop Elements graphics and selections. The rulers are helpful if you are combining photos with text (for a greeting card, for example) and want to be precise in placing and aligning the various elements. Interactive tick marks in both rulers provide constant feedback, displaying the position of any tool or pointer as you move it through the window. You can also change the ruler origin, also known as the zero point, to measure different parts of your image.
To show or hide the rulers:
From the View menu, choose Rulers to turn the rulers on and off, or press Ctrl+R/ Command+R (Figure 2.38).
Figure 2.38 Choose Rulers from the View menu to toggle the rulers on and off.
Ruler units number down and to the right, starting from the zero point, where the two rulers intersect. To measure from a given spot in an image, you can move the zero point to anywhere within the document window.
To change the zero point:
Place the pointer over the zero point of the crosshairs, in the upper-left corner document window (Figure 2.39).
Figure 2.39 The rulers' zero point establishes the origin of the rulers.
Drag the zero point to a new position in the document window.
As you drag, a set of crosshairs appears, indicating the new position of the zero point (Figure 2.40).
Figure 2.40 Drag the zero point to a new location anywhere in the document window.
Release the mouse button to set the new zero point.
To reset the zero point to its original location, double-click the zero point crosshairs in the upper-left corner of the document window.
To change the units of measure:
Open the Units & Rulers dialog box. To do so, do one of the following:
Double-click a ruler in the document window.
From the Edit menu, choose Preferences > Units & Rulers (Figure 2.41).
Figure 2.41 Choose Edit > Preferences > Rulers & Units to open the Rulers & Units dialog box.
In Mac OS X, Preferences is located under the Photoshop Elements menu.
In the Units area, from the Rulers pop-up menu, choose a unit of measure (Figure 2.42).
Figure 2.42 Rulers can be displayed in any of seven measurement systems.
The default setting is Inches. You can choose Pixels, to view the actual pixel dimensions in your image, in addition to other various unit options.
For the Point/Pica size, choose one of the following:
PostScript (72 points/inch) (Figure 2.43).
Figure 2.43 Designate points in either PostScript or Traditional units.
Traditional (72.27 points/inch).
With the advent of PostScript printing, the traditional measures of points and picas have become all but irrelevant. Most graphic design software companies base units of measure on PostScript settings rather than traditional points. Unless some special circumstance presents itself, you should leaving the Point/Pica Size option set to PostScript (72 points/inch).
You can quickly change the rulers' units of measure without having to open the Preferences dialog box. Right-click (Windows) or Contol+click (Mac OS) on either ruler. You'll see a pop-up menu appear, and you can then choose a new measurement unit.