Working with Cropping, Scaling, and Padding

The Geometry pane provides three different methods you can use to affect the output image.

Cropping

When you crop an image, you are removing video content. Often that content is unnecessary image area (such as the overscan area, which is necessary for television, but not for computers) to make what’s left seem bigger in the same frame size.

Cropping also includes a “Letterbox area of source” setting that detects image edges and automatically enters crop values to match them. This is especially useful if you want to crop out the letterbox area of a source media file.

When you adjust the crop settings, one of two things happens to the output video file’s frame size:

  • The frame size remains the same if you have chosen anything other than the 100% of source, 50% of source, and 25% of source settings in the Frame Size pop-up menu of the “Dimensions (encoded pixels)” section of the Geometry pane. This means that the source video image is scaled larger to fill the output video file’s frame size, which results in larger pixels and overall image degradation.

  • The frame size reduces by the crop amounts if you have chosen the 100% of source, 50% of source, or 25% of source settings in the Frame Size pop-up menu of the “Dimensions (encoded pixels)” section of the Geometry pane. This can result in nonstandard frame sizes.

The cropping settings are in the Source Inset (Cropping) section of the Geometry pane.

Scaling

Scaling provides a way to alter the output video file’s frame size without removing any of the source image. Most often, scaling involves shrinking your output media image size to save storage space or reduce the bit rate.

Compressor offers four basic methods for scaling the image size of an output media file.

  • Choose a percentage of the source size: Three settings scale the source image based on a percentage (100% of source, 50% of source, and 25% of source). In addition to the source image frame size, crop values will affect the actual frame size of the output video.
  • Choose a maximum frame size: Six settings scale the source image to maintain the original aspect ratio and to be as large as possible without going over the selected frame size.
  • Choose a specific frame size: There are several standard frame size settings you can choose from, such as 720x486, 720x576, and so on. When you choose any of these, the output video file’s frame size will match this setting.
  • Enter a custom value: You can enter a custom frame size. Additionally, you can have the custom frame size constrained to a common aspect ratio such as 4:3 or 16:9. When you enter a custom frame size, the output video file’s frame size will match this setting.

You are also able to define the output image’s pixel aspect ratio by choosing from a pop-up menu with the common settings.

Note: The scaling settings are only active when using the MPEG-4, QuickTime Movie, and Image Sequence output encoding formats.

The scaling settings are in the “Dimensions (encoded pixels)” section of the Geometry pane.

Padding

Padding provides a method to scale the image to a smaller size while retaining the output image’s frame size by filling the padded areas with black. Unlike cropping, padding does not remove any of the source image—the image is reduced by scaling by the padding amounts.

Padding is useful when the source image frame size is smaller than the output image frame size and you want to prevent the source image from being scaled to the output image size. By adding the correct amount of padding, the source image will remain the same size in the output image, with black filling the rest of the image frame.

Padding is automatically applied when the source video image is uncompressed NTSC 720 x 486 and the output image is 720 x 480.

There are also several common padding settings you can choose from, such as 16 x 9 and Panavision. These make it easy to have Compressor automatically enter padding values to ensure the source image retains its original aspect ratio.

The padding settings are in the Output Image Inset (Padding) section of the Geometry pane.