Working with the Straighten Controls

When you shoot photos, environmental conditions often make it difficult to frame an image that is level in relation to the horizon—either real or virtual. In Aperture, you can straighten an image so that the horizon in the image is parallel to the bottom and top edges.

Figure. Image before and after a Straighten adjustment.

You can use two different methods to straighten your images. You can use either the Straighten tool or the Straighten adjustment controls. However, you may find it most efficient to use the Straighten tool to quickly level the image so that it’s roughly straight and then use the Straighten controls for more precision.

Rotating Images with the Straighten Tool

Rotating an image with the Straighten tool is as simple as selecting the tool and dragging within the image to make it straight. However, it’s important to understand that although the image appears to enlarge as you rotate it, Aperture actually crops the image so that it fits within its rectangular border without blank edges appearing on the sides.

To straighten your image using the Straighten tool
  1. Select an image.

  2. Select the Straighten tool in the tool strip or the Full Screen view toolbar (or press G).

    The Selection tool changes to the Straighten tool.

  3. With the Straighten tool selected, drag within the image to rotate it either clockwise or counterclockwise.

As you rotate the image, a yellow grid overlay appears to help you make the horizon perfectly straight, and the image is cropped to prevent gaps from appearing in the corners of the image.

Figure. Image showing a yellow grid overlay appearing over the image to help you make the horizon perfectly level.

Note: It’s a good idea to turn zooming off when straightening an image, so that the full image fits within the Viewer. If an image is zoomed in to its actual size, you can turn off zooming by clicking the Zoom Viewer button in the tool strip or the Full Screen view toolbar (or by pressing Z).

Rotating Images with the Straighten Controls

You can also straighten an image using the Straighten adjustment controls. Using these controls provides more precision.

To straighten an image using the Straighten controls
  1. Select the image.

  2. If the Straighten controls are not shown in the Adjustments inspector or the Adjustments pane of the Inspector HUD, choose Straighten from the Adjustments pop-up menu.

  3. Change the value for the Angle parameter by doing one of the following:

    • Drag the Angle slider.

    • Click the left or right arrow in the Angle value slider, or drag in the value field.

    • Double-click the number in the Angle value slider, then enter a value from –20.0 to 20.0 degrees and press Return.

      Figure. Angle controls in the Straighten area of the Adjustments inspector.

    Decreasing the value rotates the image clockwise, and increasing the value rotates the image counterclockwise.

As you rotate the image, a yellow grid overlay appears to help you make the horizon perfectly straight, and the image is cropped to prevent gaps from appearing in the corners of the image.

Note: It’s a good idea to turn zooming off when straightening an image, so that the full image fits within the Viewer. If an image is zoomed in to its actual size, you can turn off zooming by clicking the Zoom Viewer button in the tool strip or the Full Screen view toolbar (or by pressing Z).