Sometimes, you've got to get things pixel perfect in a design. Like the days when layouts were done on acetate, it's essential to have a tool that let's you magnify your work. Enter the Loupe tool.
After clicking on the toolbar icon shown above, you'll see the following window appear:
By default, the Loupe tool follows your mouse. Getting a close-up view of your design is as simple as pointing at it. As your mouse travels across the desktop, you'll see the following information updated:
There are also several ways to customize the Loupe: in the menu bar, you'll find options to adjust the magnification level (200% to 800%) and display grid or center lines.
The "Avoid Mouse" option causes the Loupe window to automatically move away from the current mouse position. This can be convenient when you are examining a large design—it keeps the Loupe's display out of the way.
It is often useful to copy the Loupe's information into another application. There are keyboard shortcuts to copy both the magnified image (⌃⌘C) and the color values (⇧⌘C) to the clipboard. You can adjust the format of the copied color value with preferences—the default is HTML.
Finally, it can be useful to either "freeze" or "lock" the Loupe tool. When you freeze the Loupe, you get a snapshot of whatever is currently displayed. Locking the Loupe continues to update the display, but ignores any further mouse movements.
Locking is handy if you are making changes to a design and want to see an update without repositioning the mouse. A locked Loupe also helps when you are doing pixel measurements: preventing mouse movement makes it easier to drag the rectangle on the magnified pixels.
And, of course, you can easily toggle this tool on and off using the toolbar.
Click on the home button to return to the index or proceed to the next tool: Guides.