---
title: "SoftMask.Backdrop Property "
canonical: https://www.graphicsmill.com/docs/gm/P_Aurigma_GraphicsMill_Drawing_SoftMask_Backdrop.htm
product: "Graphics Mill"
---

# SoftMask.Backdrop Property 
 
Gets or sets the backdrop luminosity of the mask.
 
**Namespace:** [Aurigma.GraphicsMill.Drawing](https://www.graphicsmill.com/docs/gm/N_Aurigma_GraphicsMill_Drawing.htm.md)
 **Assembly:** Aurigma.GraphicsMill (in Aurigma.GraphicsMill.dll)
 
## Syntax
  
```csharp
public Nullable<double> Backdrop { get; set; }
```
 
### Property Value
A value from 0 to 1, or `null` to use the default backdrop (black).
 
## Remarks
  
The backdrop is used for the [Luminosity](https://www.graphicsmill.com/docs/gm/T_Aurigma_GraphicsMill_Drawing_SoftMaskMethod.htm.md) method only. In PDF it corresponds to the `/BC` entry of the soft mask dictionary.
 
## Exceptions
  
|  Exception |  Condition |
| --- | --- |
 |  System.ArgumentOutOfRangeException |  The value is less than 0 or greater than 1. |
   
## See Also

### Reference

- [SoftMask Class](https://www.graphicsmill.com/docs/gm/T_Aurigma_GraphicsMill_Drawing_SoftMask.htm.md)
- [Aurigma.GraphicsMill.Drawing Namespace](https://www.graphicsmill.com/docs/gm/N_Aurigma_GraphicsMill_Drawing.htm.md)