• sRGB vs REC709 – An introduction and FFmpeg implementations

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    1. Basic Comparison

    • What they are
      • sRGB: A standard “web”/computer-display RGB color space defined by IEC 61966-2-1. It’s used for most monitors, cameras, printers, and the vast majority of images on the Internet.
      • Rec. 709: An HD-video color space defined by ITU-R BT.709. It’s the go-to standard for HDTV broadcasts, Blu-ray discs, and professional video pipelines.
    • Why they exist
      • sRGB: Ensures consistent colors across different consumer devices (PCs, phones, webcams).
      • Rec. 709: Ensures consistent colors across video production and playback chains (cameras → editing → broadcast → TV).
    • What you’ll see
      • On your desktop or phone, images tagged sRGB will look “right” without extra tweaking.
      • On an HDTV or video-editing timeline, footage tagged Rec. 709 will display accurate contrast and hue on broadcast-grade monitors.

    2. Digging Deeper

    FeaturesRGBRec. 709
    White pointD65 (6504 K), same for bothD65 (6504 K)
    Primaries (x,y)R: (0.640, 0.330) G: (0.300, 0.600) B: (0.150, 0.060)R: (0.640, 0.330) G: (0.300, 0.600) B: (0.150, 0.060)
    Gamut sizeIdentical triangle on CIE 1931 chartIdentical to sRGB
    Gamma / transferPiecewise curve: approximate 2.2 with linear toePure power-law γ≈2.4 (often approximated as 2.2 in practice)
    Matrix coefficientsN/A (pure RGB usage)Y = 0.2126 R + 0.7152 G + 0.0722 B (Rec. 709 matrix)
    Typical bit-depth8-bit/channel (with 16-bit variants)8-bit/channel (10-bit for professional video)
    Usage metadataTagged as “sRGB” in image files (PNG, JPEG, etc.)Tagged as “bt709” in video containers (MP4, MOV)
    Color rangeFull-range RGB (0–255)Studio-range Y′CbCr (Y′ [16–235], Cb/Cr [16–240])


    Why the Small Differences Matter

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  • Open Source Nvidia Omniverse

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    blogs.nvidia.com/blog/2019/03/18/omniverse-collaboration-platform/

     

    developer.nvidia.com/nvidia-omniverse

     

    An open, Interactive 3D Design Collaboration Platform for Multi-Tool Workflows to simplify studio workflows for real-time graphics.

     

    It supports Pixar’s Universal Scene Description technology for exchanging information about modeling, shading, animation, lighting, visual effects and rendering across multiple applications.

     

    It also supports NVIDIA’s Material Definition Language, which allows artists to exchange information about surface materials across multiple tools.

     

    With Omniverse, artists can see live updates made by other artists working in different applications. They can also see changes reflected in multiple tools at the same time.

     

    For example an artist using Maya with a portal to Omniverse can collaborate with another artist using UE4 and both will see live updates of each others’ changes in their application.