Defining a Selection from an Exact Center Point

When you use the marquee tools to define a selection, the starting point is always the top-left corner of a rectangular selection or, in the case of an elliptical selection, an imaginary rectangular box. This can be problematic if what you want to do is to center the selection on an exact center point. For example, having drawn a circular object, you might want the selection to center on the epicenter of the object in order to adjust it. The workaround is to define the epicenter of the object, or of the first selection if you intend to overlap two selections, by using guides and then draw outward from the epicenter.

To find the epicenter of an existing object, take the following steps:

1. Activate the layer for the object.

2. Press Ctrl+T (Windows), ^+T (Mac OS) to activate the object's bounding box. Alternatively, select the Move tool (M) and select Show Transform Controls on the options bar.

3. Make sure that rulers are showing (View ^ Rulers) and then drag from the ruler to create a guide and let it snap to the fulcrum icon; do the same from both rulers. You should now have a cross over the epicenter of the object.

4. Press Esc if you used the transform command in step 2.

5. Having defined the epicenter, choose a selection tool (it helps to have Other Cursors in Preferences ^ Display and Cursors set to Precise for the next step).

6. Hover over the cross formed by the guides and position the pointer on the epicenter; use the change in color of the tool icon to guide you to the epicenter.

7. Hold down Alt (Windows), Opt (Mac OS) and draw outward.

You don't need to press Alt (Windows), Opt (Mac OS) before you start to define the marquee; you can do it at anytime during the operation, as long as you have not lifted the pointer off the document.

0 0

Post a comment