Definition

Rec. 2020 (ITU-R BT.2020, also known as "BT.2020" or "Ultra HD Color") is the international standard for high-definition television, particularly Ultra HD (4K/8K), and is closely linked to HDR (High Dynamic Range). The standard defines:

• RGB Primaries: Highly saturated colors for an expanded gamut
• White Point: D65 (like Rec.709)
• Color Depth: 10-bit or 12-bit (vs. 8-bit in Rec.709)
• Dynamic Range: Up to 16+ stops with HDR modes
• Gamut Volume: ~76% of the human color space (vs. 44% in Rec.709)

The standard was adopted in 2014 and is increasingly becoming the standard for streaming and cinema.

Technical Specifications

RGB Primaries and Gamut Expansion

The Rec.2020 primaries in the CIE 1931 xy color space:

Visual Implications:

• Red: Deeper red (primary red)
• Green: Much more saturated, almost neon green
• Blue: Pure, less violet

Gamut Comparison (Volume):

Rec.2020 covers 76% of the entire humanly perceptible color space.

Color Depth and Bit Quantization

Rec.2020 requires higher bit depths for gamut resolution without posterization:

Rec.709 (Standard 8-bit):

256^3 = 16,777,216 colors
Gamut Resolution: 16,777,216 / 0.44 ≈ 38 million per % of gamut

Rec.2020 (10-bit):

1024^3 = 1,073,741,824 colors
Gamut Resolution: 1,073,741,824 / 0.76 ≈ 1.4 billion per % of gamut
Sufficient for all hues without banding

Rec.2020 (12-bit, rare):

4096^3 = 68,719,476,736 colors
Practically unlimited color resolution
Archival and premium post-production

HDR Modes with Rec.2020

PQ (Perceptual Quantizer) - Dolby Vision, HDR10

Characteristics:

• Dynamic Range: 0-10,000 nits (vs. 100 nits in SDR)
• Gamma Curve: Special Perceptual Quantizer curve (not simply 2.4)
• Black Level: Absolute 0 nits (no foot/headroom like in Rec.709)
• Supported Formats: HDR10, Dolby Vision, HDR10+

Practical Consequences:

• Very dark scenes can be absolute black
• Extremely bright highlights (lights, fire, sun)
• Longer grading time for optimal results

HLG (Hybrid Log-Gamma) - Broadcast HDR

Characteristics:

• Backward-compatible: Can be viewed on SDR monitors
• Viewing Condition: Assumes standard room lighting (not completely dark)
• Gamma: Combination of log and gamma for broadcast
• Supported Formats: BBC, EBU, OBS standard

Practical Application:

• Terrestrial Broadcasting (over the air)
• Less common in streaming
• Good fallback for SDR devices

Workflow in DaVinci Resolve for Rec.2020

Project Setup

Project Settings > Color Management
- Input Color Space: Camera Format (Red, Arri, Sony)
 or Rec.2020 (for already converted material)
- Timeline Color Space: DaVinci Wide Gamut RGB (internal 32-bit float)
- Output Color Space: Rec.2020 (for HDR)
- Monitoring LUT: PQ (Dolby Vision) or HLG (Broadcast)

Timeline Configuration for HDR

1. Project Settings:

• Resolution: 3840x2160 (4K) or 7680x4320 (8K)
• Color Depth: 32-bit Float (essential for HDR)
• Rec.2020 as Output Space

1. Color Management:

• Decoder Color Space: Camera-specific
• Create Dolby Vision or HDR10 metadata

1. Monitoring:

• HDR monitor required (e.g., Dolby PRM4200)
• Set to HDR color space in Preview
• Alternative: Rec.709 monitoring with HDR-to-SDR curve

Grading for Rec.2020/HDR

Phase 1: HDR Fundamentals

• Log-to-PQ/HLG conversion automatic
• Check exposure range (0-10,000 nits for PQ)
• Use histogram in HDR mode

Phase 2: Highlight Management

• Brighter-than-white highlights enabled (~3-10 nits)
• Caution: Very bright values cannot be displayed on SDR
• Separate curves for highlights in HDR possible

Phase 3: Color Saturation

• Rec.2020 allows higher saturation
• Colors appear richer, more vibrant
• Caution: Not overly extreme saturation (can look artificial)

Phase 4: Shadow Details

• Absolute black possible (0 nits)
• Preserve details below standard black
• Black crushing not automatically possible

HDR Monitoring Setup

Ideal Hardware:

• Display: Dolby Vision certified monitor (e.g., Dolby PRM4200, Eizo CG3200)
• Colorimeter: For correct calibration
• Room: Controlled lighting (50 lux standard, dark for Dolby Vision)

Software Setup in DaVinci:

• Window > Workspace > Enable HDR Inspector
• Update Dolby Vision metadata
• Set HDR mode for monitoring in Preferences

Streaming Platforms and Rec.2020 Requirements

Gamut Mapping and Rec.2020 to Rec.709 Conversion

Downgrading to Rec.709 for Backward-Compatibility

Many productions need to deliver both Rec.2020 and Rec.709:

Scenario:

• Create master in Rec.2020 HDR
• Generate Rec.709 SDR version for broadcast
• Both versions must be visually compatible

Process:

1. Grade Rec.2020 HDR Master
2. Create Rec.709 SDR Grade Separately:

• Compress colors within Rec.709 gamut
• Adjust brightness and contrast for SDR
• Reduce dynamic range to 12 stops

1. Comparison Monitoring:

• Check Rec.709 version on SDR monitor
• Check Rec.2020 version on HDR monitor
• Ensure consistency

Automated Gamut Mapping in DaVinci

Curve Node Gamut Mapping:

Node > Gamut Mapping Mode
- Soft Clip: Gentle reduction over/outside gamut
- Hard Clip: Sharp clipping
- Preserve Hue: Attempts to maintain hues

Secondary Correction for Color Shifts:

• Color Range Isolation on saturated colors
• Saturation and Hue fine-tuning
• Luminance-based selective grading

10-bit vs. 8-bit and Posterization

Banding Artifacts in 8-bit vs. 10-bit

Scenario: Blue Sky Gradient

8-bit (Rec.709):

Only 256 blue variations available
Visible banding in large areas

10-bit (Rec.2020):

1024 blue variations available
Clean, continuous gradients

Practical Implication:

• 10-bit is the minimum for Rec.2020
• Posterization is a major issue with incorrect configuration
• Always export 10-bit for archiving

Common Errors and Solutions

Practical Scenarios

Scenario 1: Netflix 4K HDR Delivery

Production for Netflix with 4K and HDR:

1. Project in Rec.2020 HDR10 in DaVinci
2. Grading with HDR monitor
3. Rec.2020 HDR10 with Dolby Vision optional
4. Compliance test on Netflix servers
5. Export with Netflix specs

Scenario 2: Cinema + Streaming Hybrid Distribution

Simultaneous distribution for cinema (DCI) and streaming (Rec.2020 HDR):

1. Grade master in DCI-P3 (cinema standard)
2. Convert DCI to Rec.2020 HDR
3. Perform grading adjustments for HDR
4. Cinema: Produce DCI-P3 view
5. Streaming: Deliver Rec.2020 HDR

Scenario 3: Documentary with Limited HDR Equipment

Production without access to HDR monitors:

1. Grade in Rec.709 (SDR)
2. With grading notes for HDR adjustments
3. Later, with a professional colorist: Upscale SDR to HDR grade
4. Or: Perform separate Rec.2020 HDR grade using a Rec.709 monitor

Calibration and Monitoring for Rec.2020/HDR

Monitor Requirements

Necessary for professional HDR grading:

• Resolution: Minimum 4K for 4K content
• Brightness: 1000+ nits for PQ HDR
• Color Gamut: DCI-P3 or larger
• Certification: Dolby Vision or HDR10

Examples:

• Dolby PRM4200 (4K HDR)
• Sony BVM-HX310 (HDR, very expensive)
• Eizo CG3200 (limited, but calibratable)

Calibration Process

1. Room Darkness: Ideally < 5 lux for PQ grading
2. Monitor Warm-up Phase: 30 minutes minimum
3. Colorimeter Calibration: According to manufacturer's specifications
4. Dolby Vision Profile: Load onto the monitor
5. Test Patterns: Check gradation and color accuracy

Summary

Rec.2020 is the standard for future productions and premium distribution. The expanded color gamut, higher bit depth, and HDR support offer creative possibilities but also require careful calibration and professional grading techniques. Investment in the right hardware and workflow is essential for professional results.