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# Scaling Mode Constants

Supported constant values for the [`kVTPixelTransferPropertyKey_ScalingMode`](/documentation/VideoToolbox/kVTPixelTransferPropertyKey_ScalingMode) key.

## Topics

### Scaling Modes

[`let kVTScalingMode_Normal: CFString`](/documentation/VideoToolbox/kVTScalingMode_Normal)

The full width and height of the source image buffer is stretched to the full width and height of the destination image buffer.

[`let kVTScalingMode_CropSourceToCleanAperture: CFString`](/documentation/VideoToolbox/kVTScalingMode_CropSourceToCleanAperture)

The source image buffer’s clean aperture is scaled to the destination clean aperture.

[`let kVTScalingMode_Letterbox: CFString`](/documentation/VideoToolbox/kVTScalingMode_Letterbox)

The source image buffer’s clean aperture is scaled to a rectangle fitted inside the  destination clean aperture that preserves the source picture aspect ratio.

[`let kVTScalingMode_Trim: CFString`](/documentation/VideoToolbox/kVTScalingMode_Trim)

The source image buffer’s clean aperture is scaled to a rectangle that completely fills the destination clean aperture and preserves the source picture aspect ratio.


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