---
title: "03 - Symbol Mapper Pre-process Group"
url: "https://help.maxon.net/rg/en-us/Content/html/03-symbol-mapper-pre-process.html"
section_path: "Stylize > Symbol-Mapper > 03 - Symbol Mapper Pre-process Group"
description: "Depending on your settings, Symbol Mapper can change which characters display in a given space according to that location’s underlying brightness values …"
---

## Symbol Mapper: Pre-process Group

Depending on your settings, Symbol Mapper can change which characters display in a given space according to that location’s underlying brightness values, with larger characters sometimes providing more apparent brightness in a space. (Spoiler: You can best see this behavior with **Random Seed** set to 0, **Symbol Limit** at 64, and **All Characters** checked, or you can select one of the **Density** presets.) The Pre-process group offers two controls that change the brightness of the underlying source content, **Brightness** and **Contrast**, and thus can influence which symbols get mapped into the Symbol Mapper effect.

**Brightness** values can range from -150 to 150. The following image shows an example of raising the default **Brightness** value of 0 to 100. Note that we also have **Glow Intensity** set to 100 (not shown) to accentuate the impact of changing the **Brightness**. You’ll observe how the characters selected by Symbol Mapper change based solely on underlying brightness values.

![Image: Universe_SymbolMapper_Brightness-0vs101.png](https://help.maxon.net/rg/en-us/Content/Resources/Images/Universe_SymbolMapper_Brightness-0vs101.png)

For a slightly different look at how Symbol Mapper makes these choices, let’s run the **Contrast** control from its lowest (-100) to highest (100) value.

[Video: Universe_SymbolMapper_Constrast.mp4](https://help.maxon.net/rg/en-us/Content/Resources/Multimedia/Universe_SymbolMapper_Constrast.mp4)

At -100, Symbol Mapper fills the preview with glowing white dollar symbols. This may seem counter-intuitive, but keep in mind that **Brightness** is at 100. **Contrast** at -100 presents a uniform gray across the screen while, at 100, **Contrast** pushes everything toward lights and darks.