# SmoothRollingGuidance node¶

*This documentation is for version 2.0 of SmoothRollingGuidance.*

## Description¶

Filter out details under a given scale using the Rolling Guidance filter.

Rolling Guidance is described fully in http://www.cse.cuhk.edu.hk/~leojia/projects/rollguidance/

Iterates the ‘blur_bilateral’ function from the CImg library.

CImg is a free, open-source library distributed under the CeCILL-C (close to the GNU LGPL) or CeCILL (compatible with the GNU GPL) licenses. It can be used in commercial applications (see http://cimg.eu).

## Inputs¶

Input | Description | Optional |
---|---|---|

Source | No | |

Mask | Yes |

## Controls¶

Parameter / script name | Type | Default | Function |
---|---|---|---|

Spatial Std Dev / `sigma_s` |
Double | 10 | Standard deviation of the spatial kernel, in pixel units (>=0). Details smaller than this size are filtered out. |

Value Std Dev / `sigma_r` |
Double | 0.1 | Standard deviation of the range kernel, in intensity units (>=0). A reasonable value is 1/10 of the intensity range. In the context of denoising, Liu et al. (“Noise estimation from a single image”, CVPR2006) recommend a value of 1.95*sigma_n, where sigma_n is the local image noise. |

Iterations / `iterations` |
Integer | 4 | Number of iterations of the rolling guidance filter. 1 corresponds to Gaussian smoothing. A reasonable value is 4. |

(Un)premult / `premult` |
Boolean | Off | Divide the image by the alpha channel before processing, and re-multiply it afterwards. Use if the input images are premultiplied. |

Invert Mask / `maskInvert` |
Boolean | Off | When checked, the effect is fully applied where the mask is 0. |

Mix / `mix` |
Double | 1 | Mix factor between the original and the transformed image. |