GMImage.LevelChannel
--------------------

Level image channel.

| Component | Version | macOS | Windows | Linux | Server | iOS SDK |
|---|---|---|---|---|---|---|
| [GraphicsMagick](component_GraphicsMagick.md) | [2.0](newinversion20.md) | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |

MBS( "GMImage.LevelChannel"; ImageRef; ChannelType; blackPoint; whitePoint { ; midPoint } ) 

**MBS**( **"GMImage.LevelChannel";** /\* Level image channel. \*/  
**$ImageRef**; /\* The image reference number.e.g. 1 \*/   
**$ChannelType**; /\* One of the following values: RedChannel = 1 (RGB Red channel), CyanChannel = 2 (CMYK Cyan channel), GreenChannel = 3 (RGB Green channel), MagentaChannel = 4 (CMYK Magenta channel), BlueChannel = 5 (RGB Blue channel), YellowChannel = 6 (CMYK Yellow channel), OpacityChannel = 7 (Opacity channel), BlackChannel = 8 (CMYK Black (K) channel), MatteChannel = 9 (Same as Opacity channel (deprecated)), AllChannels = 10 (Color channels), GrayChannel = 11 (Color channels represent an intensity.)e.g. 1 \*/   
**$blackPoint**; /\* The black point.e.g. 0 \*/   
**$whitePoint**; /\* The white point.e.g. 1.0 \*/   
**$midPoint**) /\* Optional; The middle point.e.g. 1.0 \*/ 

### Parameters

| Parameter | Description | Example | Flags |
|---|---|---|---|
| ImageRef | The image reference number. | 1 |  |
| ChannelType | One of the following values: RedChannel = 1 (RGB Red channel), CyanChannel = 2 (CMYK Cyan channel), GreenChannel = 3 (RGB Green channel), MagentaChannel = 4 (CMYK Magenta channel), BlueChannel = 5 (RGB Blue channel), YellowChannel = 6 (CMYK Yellow channel), OpacityChannel = 7 (Opacity channel), BlackChannel = 8 (CMYK Black (K) channel), MatteChannel = 9 (Same as Opacity channel (deprecated)), AllChannels = 10 (Color channels), GrayChannel = 11 (Color channels represent an intensity.) | 1 |  |
| blackPoint | The black point. | 0 |  |
| whitePoint | The white point. | 1.0 |  |
| midPoint | The middle point. | 1.0 | Optional |

### Result

Returns "OK" on success.

### Description

Level image channel.   
Adjust the levels of the image by scaling the colors falling between specified white and black points to the full available quantum range. The parameters provided represent the black, mid (gamma), and white points. The black point specifies the darkest color in the image. Colors darker than the black point are set to zero. Mid point (gamma) specifies a gamma correction to apply to the image. White point specifies the lightest color in the image. Colors brighter than the white point are set to the maximum quantum value. The black and white point have the valid range 0 to MaxRGB while mid (gamma) has a useful range of 0 to ten.  
### See also

- [GMImage.BlurChannel](GMImageBlurChannel.md)
- [GMImage.CopyChannel](GMImageCopyChannel.md)
- [GMImage.InvertChannel](GMImageInvertChannel.md)

This function checks for a license.

Created 18th August 2014 , last changed 18th August 2014

  
[GMImage.Level](GMImageLevel.md) - [GMImage.List](GMImageList.md)

[HTML Version](GMImageLevelChannel.shtml)