When it comes time to touch up the details in your picture, you may want to get a closer look at your work. You can exercise precise, pixel level control by using the Zoom Tool.
Move your cursor near the portion of the picture which you wish to enlarge. Hold down the left mouse button and drag to surround the desired portion of the picture. When you have fully enclosed the area you want to look at, release the mouse button. Additionally, you can zoom in or out one magnification level at a time by simply clicking the left or right mouse buttons respectively.
The Option Bar as it appears when the Zoom Tool is active.
You also can change the magnification level by adjusting the Zoom slider control that appears on the Option Bar when the Zoom tool is active. To return to the actual size (1:1) view of your picture, click the button next to the zoom slider control. Clicking the will automatically adjust the magnification so that the picture fits onto your screen.
You can also zoom in or out at any time by rotating your mouse wheel.
Another way to adjust the magnification level at any time is to use the Navigator's zoom slider. The Navigator also displays a thumbnail view of your picture.