---
title: "04 - Pre-Process"
url: "https://help.maxon.net/rg/en-us/Content/html/04-Starglow-pre-process.html"
section_path: "Blurs and Glows > Starglow > 04 - Pre-Process"
description: "The pre-process section lets you set a threshold for controlling where the Starglow effect appears. It also lets you use a built-in circular mask to …"
---

# 04 - Pre-Process

Starglow

## Pre-Process

The pre-process section lets you set a threshold for controlling where the Starglow effect appears. It also lets you use a built-in circular mask to restrict the glow area.

### Threshold

Threshold defines the minimum level for highlights. A low value will give more glow in the image, and a high value will make only the very bright areas glow. The images below show Starglow output using a shot of the sun on water with different Threshold values.

![source](https://help.maxon.net/rg/en-us/Content/Resources/Images/source_trapcode-starglow.jpg)\
Source\
![thresh_hi](https://help.maxon.net/rg/en-us/Content/Resources/Images/thresh_hi_trapcode-starglow.jpg)\
High Threshold

![thresh_lo](https://help.maxon.net/rg/en-us/Content/Resources/Images/thresh_lo_trapcode-starglow.jpg)\
Low Threshold

**Threshold Soft:** This controls the softness of the border between lowlights and highlights.\
**Use Mask:** Check this to enable the internal circular mask.\
**Mask Radius:** This control sets the size of the internal circular mask in pixels.\
**Mask Feather:** The Mask Feather value sets the softness of the internal circular mask.\
**Mask Position:** This control defines the center point of the circular mask.