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# vImageTransferFunction

A transfer function to convert from linear to nonlinear RGB.

```
struct vImageTransferFunction
```

## Overview

The transfer function here is in the style of ITU-R BT.709, and is the inverse operation of what appears in an ICC color profile. For example, the following code defines the transfer function for ITU-R BT.709-5:

```swift
var transferFunction = vImageTransferFunction(
    c0: 1.099,
    c1: 1.0,
    c2: 0.0,
    c3: -0.099,
    gamma: 0.45,
    cutoff: 0.018,
    c4: 4.5,
    c5: 0)
```

The following is the conversion:

```c
if (R >= cutoff) {
    R' = c0 * pow( c1 * R + c2, gamma ) + c3
} 
else {
    R' = c4 * R + c5                             
}
```

## Topics

### Initializers

[`init(c0:c1:c2:c3:gamma:cutoff:c4:c5:)`](/documentation/Accelerate/vImageTransferFunction/init(c0:c1:c2:c3:gamma:cutoff:c4:c5:))

Creates a structure that represents a transfer function to convert from linear to nonlinear RGB.

[`init()`](/documentation/Accelerate/vImageTransferFunction/init())

Creates an empty transfer function structure.

### Transfer function properties

[`c0`](/documentation/Accelerate/vImageTransferFunction/c0)

The `c0` in the transfer function.

[`c1`](/documentation/Accelerate/vImageTransferFunction/c1)

The `c1` in the transfer function.

[`c2`](/documentation/Accelerate/vImageTransferFunction/c2)

The `c2` in the transfer function.

[`c3`](/documentation/Accelerate/vImageTransferFunction/c3)

The `c3` in the transfer function.

[`cutoff`](/documentation/Accelerate/vImageTransferFunction/cutoff)

The `cutoff` in the transfer function.

[`gamma`](/documentation/Accelerate/vImageTransferFunction/gamma)

The `gamma` in the transfer function.

[`c4`](/documentation/Accelerate/vImageTransferFunction/c4)

The `c4` in the transfer function.

[`c5`](/documentation/Accelerate/vImageTransferFunction/c5)

The `c5` in the transfer function.


---

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