---
title: contrastAdjustment
framework: vision
role: symbol
role_heading: Instance Property
path: vision/detectcontoursrequest/contrastadjustment
---

# contrastAdjustment

The amount by which to adjust the image contrast.

## Declaration

```swift
var contrastAdjustment: Float
```

## Discussion

Discussion Contour detection works best with high-contrast images. The default value of this property is 2.0, which doubles the image contrast to achieve the most accurate results. This property supports a value range from 0.0 to 3.0.

## See Also

### Configuring a request

- [contrastPivot](vision/detectcontoursrequest/contrastpivot.md)
- [detectsDarkOnLight](vision/detectcontoursrequest/detectsdarkonlight.md)
- [maximumImageDimension](vision/detectcontoursrequest/maximumimagedimension.md)