【Unity】Getting Started with Unity Post Processing: Enhancing Visual Quality with Screen Effects

Overview

Tested with: Unity 2022.3 LTS / Unity 6 Scope: Built-in Render Pipeline and URP (HDRP is not covered in this article)

"The scene looks too flat..." "I want to create a cinematic atmosphere..." "I need richer visuals..."

In game development, you often face these kinds of visual challenges. Post processing is a technique that applies effects (filters) to the rendered result of what the camera sees. Just like filters in photo apps or effects in image editing software, you can adjust the overall look of the screen with various effects including Bloom, Color Grading, and Depth of Field.

Two Implementation Approaches

In Unity, the implementation approach differs depending on the render pipeline you are using.

Post Processing Stack v2 (for Built-in RP)

• Install from the Package Manager
• Add a Post-Process Layer component to the camera
• Manage with a Post-Process Volume component
• Create a profile and add effects

Volume Override (for URP/HDRP)

• Available by default in URP
• Uses Volume components
• Add effects to a Volume Profile
• More integrated workflow

Major Effects

Bloom

The most commonly used effect, Bloom emphasizes light and creates a glow appearance.

Post Processing Stack v2 (Built-in RP)

Parameter	Description
Intensity	Strength of the light
Threshold	Brightness threshold for applying the effect
Diffusion	Light spread (1-10)
Color	Bloom tint color
Fast Mode	Lower quality but faster

URP Volume

Parameter	Description
Intensity	Strength of the light
Threshold	Brightness threshold for applying the effect
Scatter	Light spread (0-1)
Tint	Bloom tint color
High Quality Filtering	Enables high-quality filtering

Note: Parameter names differ between Post Processing Stack v2 and URP. "Diffusion" and "Scatter", "Color" and "Tint" are functionally equivalent.

Bloom Adjustment Guidelines

Use Case	Intensity	Threshold	Scatter(URP) / Diffusion(v2)
Natural glow	0.2-0.5	0.9-1.0	0.5-0.6 / 5-6
Standard look	0.5-1.0	0.8-0.9	0.6-0.7 / 6-7
Emphasized look	1.0-2.0	0.5-0.8	0.7-0.8 / 7-8
Extreme effect	2.0+	0.5 or below	0.8-1.0 / 8-10

Optimizing Bloom for URP

To optimize Bloom for mobile:

• Downscale: Check to process at a lower resolution (OFF by default)
• Max Iterations: Lower values reduce processing cost (default 6, recommended 3-4 for mobile)
• High Quality Filtering: Turn OFF for lighter performance

Color Grading

A color correction feature that adjusts the overall color tone of the screen. It is one of the most important effects for creating a cinematic look.

Key Parameters

Parameter	Description	Adjustment Example
Tonemapping	HDR to LDR conversion method	ACES recommended (film industry standard)
Post Exposure	Overall brightness	Adjust within -1 to 1 range
Contrast	Contrast	10-30 for a tighter image
Saturation	Saturation	-20 for serious mood, +20 for vibrant
Temperature	Color temperature	Negative for cool, positive for warm

Lift / Gamma / Gain

• Lift: Adjusts shadow color tones (color of dark areas)
• Gamma: Adjusts midtone color (overall atmosphere)
• Gain: Adjusts highlight color tones (color of bright areas)

Tonemapping recommendation: ACES is the standard tonemapping used in the film industry, producing a natural and cinematic look. It is particularly effective for HDR content.

Ambient Occlusion (AO)

Adds shadows to corners and edges of objects, providing realistic spatial depth. However, it is performance-heavy, so it is primarily suited for desktop/console platforms.

Depth of Field

Simulates camera focus. By focusing at a specific distance and blurring everything else, you can achieve a cinematic look.

URP Mode Selection

Mode	Quality	Cost	Use Case
Gaussian	Standard	Light	Mobile, performance-focused
Bokeh	High quality	Heavy	PC/Console, cinematic look

Bokeh mode: Produces high-quality bokeh by simulating camera lens aperture shapes, but is too heavy for mobile due to its processing cost.

Vignette

An effect that darkens the screen edges, used for retro aesthetics or blending the screen together.

Other Effects

• Auto Exposure - Simulates dark/light adaptation
• Chromatic Aberration - Simulates lens color fringing
• Grain - Adds noise to the screen for a film-like look
• Motion Blur - Adds blur to movement for a sense of speed
• Lens Distortion - Creates a fisheye lens-like distortion

Implementation Steps for Built-in RP

1. Installing the Package

1. Open Window > Package Manager
2. Search for "Post Processing" and install it

2. Camera Setup

1. Select the Main Camera
2. Add the "Post-Process Layer" component
3. Set the Layer (e.g., Default)

3. Creating the Volume

1. Create an empty GameObject
2. Add the "Post-Process Volume" component
3. Turn on Is Global
4. Create a new Profile

4. Adding Effects

1. Click Add Effect... on the Profile
2. Select the desired effect
3. Adjust the parameters of each effect

Implementation Steps for URP

1. Creating a Global Volume

1. Right-click in the Hierarchy
2. Select Volume > Global Volume
3. A GameObject is created

2. Configuring the Volume Profile

1. Click "New" on the Volume component's "Profile"
2. A Volume Profile is created

3. Adding Effects

1. Click "Add Override"
2. Select the desired effect
3. Adjust the parameters of each effect

4. Verify Camera Settings

Make sure Post Processing is enabled on the camera.

Changes in URP 14+ (Unity 2023.1+): Starting with URP 14, Post Processing is enabled by default on cameras. The settings UI has also changed, and you toggle Post Processing on/off from the Render Type settings screen.

Area-Specific Effects with Local Volume

While Global Volume affects the entire scene, Local Volume lets you apply effects only to specific areas.

Configuration

1. Create an empty GameObject
2. Add a Volume component
3. Turn Is Global off
4. Add a Collider (such as a Box Collider)
5. Configure the Volume Profile and Blend Distance

Use Cases

• Cave area: Darken the scene and strengthen Vignette
• Magical forest: Increase Bloom for a fantasy atmosphere
• Danger zone: Add a red tint with Color Grading

Blend Distance: Sets how many meters from the Volume boundary the effect gradually applies. Values of 2-5 are recommended to avoid abrupt transitions.

Recommended Combinations

Here are preset examples that beginners can try right away.

Cinematic

• Color Grading: Tonemapping=ACES, Contrast=20, Saturation=-10
• Vignette: Intensity=0.3
• Bloom: Intensity=0.3, Threshold=0.9

Horror

• Color Grading: Saturation=-30, Temperature=-10 (cool tones)
• Grain: Intensity=0.3
• Vignette: Intensity=0.5

Fantasy

• Bloom: Intensity=1.0, Threshold=0.7
• Color Grading: Saturation=20, Temperature=10 (warm tones)

Retro Game

• Color Grading: Contrast=40, Saturation=-20
• Chromatic Aberration: Intensity=0.2
• Grain: Intensity=0.4

Performance Impact

High-Cost Effects

Effect	Cost Level	Notes
Ambient Occlusion	Very High	Post processing effect
Motion Blur	High	Post processing effect
Screen Space Reflection	High	Rendering feature (implemented as Renderer Feature in URP)
Depth of Field	Medium-High	Post processing effect

Note: Screen Space Reflection is technically not a post processing effect but part of the rendering pipeline. In URP, it is added as a Renderer Feature.

Optimization Tips

• Only enable necessary properties - Turn off unused parameters
• Use Fast Mode - Available for effects like Bloom
• Use lightweight effects for mobile - Choose lighter effects like Vignette
• Lower the resolution - Leverage downsampling
• Minimize effect combinations - Only use what you need

VR Considerations

The following effects are not recommended in VR as they can cause motion sickness.

• Depth of Field - Mismatch between visual and actual focus
• Motion Blur - Inconsistency with head movement
• Chromatic Aberration - Strong settings cause eye fatigue
• Lens Distortion - Mismatch with actual field of view
• Grain - Strong settings cause discomfort
• Vignette - Strong settings create a sense of restricted vision

Common Issues and Solutions

Issue 1: Effects Not Showing

• Check if Post Processing is enabled on the camera
• Verify Volume settings are correct
• Check that Layer settings match (Built-in RP)

Issue 2: Performance Drops

• Disable unnecessary effects
• Enable Fast Mode
• Lower the resolution
• Use only lightweight effects for mobile

Issue 3: Overexposed (Washed Out)

• Lower Bloom Intensity
• Adjust Post-exposure in Color Grading
• Review HDR color settings

Issue 4: Too Dark / Too Bright

• Adjust with Color Grading
• Use Auto Exposure
• Review lighting settings

Summary

Post processing is a powerful technique for enhancing the overall visual quality of your screen.

• Bloom - Glow effects, the most commonly used
• Color Grading - Color correction, creates a cinematic atmosphere
• Depth of Field - Focus effects, highlights the subject of interest
• Vignette - Darkens screen edges, retro aesthetic

Choose the right implementation approach for your render pipeline, and use effects effectively while keeping performance in mind.

Further Learning

• Unity Documentation - Post Processing (Built-in RP)