Bloom and color grading in Unity - Step-by-Step Execution

Concept Flow - Bloom and color grading

Start: Render Scene

↓

Extract Bright Areas

↓

Apply Blur to Bright Areas

↓

Combine Blurred Bright Areas with Original Scene

↓

Apply Color Grading Adjustments

↓

Output Final Image

The rendering process extracts bright parts, blurs them to create bloom, then combines with the original image, and finally applies color grading to adjust colors.

Execution Sample

Unity

using UnityEngine;
using UnityEngine.Rendering.PostProcessing;

public class BloomColorGradingExample : MonoBehaviour {
    public PostProcessVolume volume;
    void Start() {
        var bloom = volume.profile.GetSetting<Bloom>();
        bloom.intensity.value = 5f;
        var colorGrading = volume.profile.GetSetting<ColorGrading>();
        colorGrading.saturation.value = -20f;
    }
}

This code sets bloom intensity and reduces color saturation using Unity's PostProcessing stack.

Execution Table

Step	Action	Parameter Changed	Value	Effect
1	Start rendering scene	-	-	Scene rendered normally
2	Extract bright areas	Threshold	Default	Bright parts isolated
3	Apply blur to bright areas	Blur amount	Default	Bright areas blurred for glow
4	Combine blurred bright areas with original	Intensity	5	Strong bloom glow added
5	Apply color grading	Saturation	-20	Colors become less vibrant
6	Output final image	-	-	Image with bloom and color grading shown

💡 Rendering completes with bloom and color grading applied to the final image.

Variable Tracker

Variable	Start	After Step 4	After Step 5	Final
bloom.intensity.value	Default (1)	5	5	5
colorGrading.saturation.value	Default (0)	0	-20	-20

Key Moments - 2 Insights

Why does increasing bloom intensity make bright areas glow more?

Because in step 4 of the execution_table, the blurred bright areas are combined with the original image multiplied by the bloom intensity value, so higher intensity means stronger glow.

Why does reducing saturation in color grading make colors look dull?

As shown in step 5, lowering saturation reduces the vividness of colors, making them appear less vibrant and more grayish.

Visual Quiz - 3 Questions

Look at the execution_table, what is the bloom intensity value after step 4?

A 5

B 1

C 0

D -20

💡 Hint

Check the 'Parameter Changed' and 'Value' columns at step 4 in execution_table.

At which step is color saturation changed?

A Step 2

B Step 4

C Step 5

D Step 6

💡 Hint

Look for 'Apply color grading' action in execution_table.

If bloom intensity was set to 0, what would happen to the final image?

A Colors would be more saturated

B No bloom glow would appear

C Bright areas would be more blurred

D Image would be black and white

💡 Hint

Refer to variable_tracker and execution_table step 4 about bloom intensity effect.

Concept Snapshot

Bloom adds glow by blurring bright parts and mixing them back.
Color grading adjusts colors like saturation and contrast.
In Unity, use PostProcessVolume to set bloom intensity and color grading.
Higher bloom intensity means stronger glow.
Lower saturation makes colors duller.
These effects combine to enhance scene visuals.

Full Transcript

This visual execution trace shows how bloom and color grading work in Unity's rendering pipeline. First, the scene is rendered normally. Then bright areas are extracted and blurred to create a glow effect called bloom. This blurred glow is combined with the original image, controlled by bloom intensity. Next, color grading adjusts the image colors, for example by reducing saturation to make colors less vibrant. The final image shows the combined effect of bloom and color grading. Variables like bloom intensity and color grading saturation change step-by-step, affecting the final look. Understanding these steps helps beginners see how visual effects enhance game graphics.