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Testcard Raw Y'CbCr 4:2:2 Assets

The pal-raw and ntsc-raw folders contain raw Y'CbCr 4:2:2 color bar frames for PAL EBU and NTSC EIA at 75% and 100% saturation. Files are single-frame images sized to the active picture area only.

Format Specification

Raw video file containing ITU-R BT.601-derived component video:

Video Standard

  • Y'CbCr 4:2:2 sampling structure
  • 10-bit quantization, packed as YUYV
  • Studio range (ITU-R BT.601):
  • Y' (luma): 64–940 (876 quantization levels)
  • Cb/Cr (chroma): 64–960 (896 quantization levels, centered at 512)
  • Byte order: Little-endian
  • Field order: Top field first (interlaced)

Active Picture Dimensions

  • PAL: 720 × 576 @ 50i
  • NTSC: 720 × 480 @ 59.94i

Bit Packing

Each 10-bit component value is stored in a 16-bit (2-byte) little-endian word: - Bits 0–9: 10-bit sample value (valid range) - Bits 10–15: Unused (should be zero)

Example: A luma value of 940 (0x3AC) is stored as bytes 0xAC 0x03

Files

  • pal-ebu-colorbars-100.raw — 720×576, PAL EBU bars, 100% saturation
  • pal-ebu-colorbars-75.raw — 720×576, PAL EBU bars, 75% saturation
  • ntsc-eia-colorbars-100.raw — 720×480, NTSC EIA/SMPTE bars, 100% saturation
  • ntsc-eia-colorbars-75.raw — 720×480, NTSC EIA/SMPTE bars, 75% saturation

YUYV Packing Format

Each pair of horizontally-adjacent pixels is encoded as 4 components (8 bytes total):

Component Description Bytes Applies to
Y0 Luma for pixel 0 0–1 Pixel 0
Cb (U) Blue-difference chroma 2–3 Pixels 0 & 1 (shared)
Y1 Luma for pixel 1 4–5 Pixel 1
Cr (V) Red-differenc (10-bit)

Y' (Luma)

Level Value Description
Black 64 Reference black (0% video)
White 940 Reference white (100% video)
Range 876 levels 64–940 inclusive
Headroom Below 64, above 940 Reserved for superblack/superwhite

Cb/Cr (Chroma)

Level Value Description
Minimum 64 Maximum color difference (negative)
Neutral 512 Zero chroma (grayscale)
Maximum 960 Maximum color difference (positive)
Range 896 levels 64–960 inclusive, centered at 512

RGB to Y'CbCr Conversion (BT.601)

Y'  = 0.299·R + 0.587·G + 0.114·B
Cb  = -0.168736·R - 0.331264·G + 0.5·B
Cr  = 0.5·R - 0.418688·G - 0.081312·B
Where R, G, B are normalized to 0.0–1.0, then scaled to studio range. 512 64 512

Chroma Subsampling

4:2:2 subsampling means: - Each pixel has its own luma (Y') sample - Pairs of horizontal pixels share chroma (Cb/Cr) samples - Chroma is averaged/interpolated for the pixel pair

Calculation

  • Each pixel pair = 4 components × 2 bytes = 8 bytes
  • Horizontal pixel pairs per line = width ÷ 2
  • Total bytes = (width ÷ 2) × height × 8

Actual Sizes

Format Dimensions Calculation Size
PAL 720 × 576 (720÷2) × 576 × 8 1,658,880 bytes (1.58 MiB)
*Usage Notes

Scope

  • Files contain active picture area only (no blanking or VBI)
  • Single frame per file (no field/frame sequencing)
  • Top field first ordering (line 0 = top field, line 1 = bottom field, etc.)

Applications

  • Deterministic encoder test inputs with well-defined digital levels
  • Y'CbCr domain validation and analysis
  • Baseline reference for colorimetry testing
  • ITU-R BT.601 compliance verification

Important Considerations

  1. Field structure: Data represents a full frame with interlaced field ordering
  2. Blanking: Add horizontal/vertical blanking and VBI as needed for your application
  3. Timing: Frame rate implied by format (50i for PAL, 59.94i for NTSC) but not encoded in file
  4. Color space: Assumes ITU-R BT.601 color primaries and transfer characteristics

Reading the Files

To read these files programmatically: 

import struct

def read_yuyv_frame(filename, width, height):
    with open(filename, 'rb') as f:
        data = f.read()

    # Each pixel pair = 8 bytes (4 × 16-bit components)
    expected_size = (width // 2) * height * 8
    assert len(data) == expected_size

    # Unpack as little-endian 16-bit unsigned integers
    components = struct.unpack(f'<{len(data)//2}H', data)

    # Components are in Y0, Cb, Y1, Cr order
    # Process in groups of 4...
- Cb/Cr (Chroma): - Minimum: 64 - Neutral: 512 (zero chroma) - Maximum: 960 - Range: 896 levels

Color Ordering (left to right)

White, Yellow, Cyan, Green, Magenta, Red, Blue, Black.

File Sizes (bytes)

  • PAL: 720 × 576 × 4 bytes per pixel pair = (720/2) × 576 × 4 × 2 = 1,658,880 bytes
  • NTSC: 720 × 480 × 4 bytes per pixel pair = (720/2) × 480 × 4 × 2 = 1,382,400 bytes

Generation

To regenerate these files, run: 

python3 scripts/generate_pal_yuv422_colorbars.py
python3 scripts/generate_ntsc_yuv422_colorbars.py

Notes

  • Images contain only the active picture region; add your own blanking/VBI if needed.
  • Use these as baseline deterministic inputs for encoder tests with well-defined digital levels.
  • Chroma subsampling is 4:2:2: each pixel has independent luma, but chroma is horizontally shared between pixel pairs.