Easy viewing is very important component of correct editing, especially while dealing with larger images. To view the whole picture we have to zoom out, to view minor details we are to zoom in; to see a picture as it really is, we have to use the actual size.
§ 1. In an open document window, notice the initial zoom value.
§ 2. In the Toolbox, click "magnifying glass" button to activate the Zoom Tool.
§ 3. By default, the tool "zooms in". Click on the image to magnify the view. Notice the new zoom value. Click several more times. Now the image may appear jagged, but this is just the sizing function and not a problem with your image. Please keep in mind that you magnify the view and not the image itself.
§ 4. Click the "Zoom Out" button in the Options bar or hold down [Alt] key to switch the tool's operating mode. Then click on the image to reduce its view.
§ 5. With a significant zoom value, you can discern minor details but you can't see the entire image, because it is too large. To explore the hidden parts of the image open the Navigator palette ("Window > Navigator").
§ 6. In the center of the Navigator you can see your image thumbnail; its visible portion - document window area - is marked with a red rectangle. Drag the rectangle across the thumbnail and notice the image in the document window updating.