Apple Aperture 2 - Manual (Page 402)

402 Part III Performing Image Adjustments
Working with the Crop Controls
You use the Crop tool and Crop adjustment controls when you want to improve the
composition of your image by trimming the edges, or when you want to change the
aspect ratio of the image. For example, you can change an image’s aspect ratio from
4 x 6 to 3 x 5.
There are two methods for cropping an image: you can either use the Crop tool to
manually crop the image, or you can use the Crop adjustment controls. The method you
choose is determined by the level of precision you require. The Crop tool provides a fast
freehand method and works in conjunction with a Crop HUD that contains controls for
setting the aspect ratio of the crop. The extra precision provided by the Crop controls is
useful when you want to specify exact dimensions for the cropped image.
Before Crop adjustment
After Crop adjustment