Filmic Tonemapping - EA 2006

1. Filmic Tone Mapping Haarm-Pieter Duiker – EALA George Borshukov – WWVG 2006/10/27

2. History of Color In Video Games • Progression of Game Graphics – Galaga – Super Mario Jump forward a few years – Bond – Madden – Need For Speed – Gears of War

3. History of Color In Video Games Copyright @1982 Namco Corp.

4. History of Color In Video Games Copyright @1988 Nintendo of America Inc

5. History of Color In Video Games Copyright @ 2003-2004 Electronic Arts Inc

9. HDR and Next-gen Hardware • What problems do new hardware capabilities bring with them? – Working with HDR data implies Linear color math and workflows – So you need to… • Linearize your textures on read • Compensate for the characteristics of display devices through Tone Mapping • Choose a Tone Mapping algorithm

14. What Does Linear Data Look Like? • Issues – Overly Contrasty – The dynamic range viewable on screen is relatively small – Trying to work with this data in integer formats will quickly lead to quantization artifacts

19. A Filmic Approach to Tone Mapping • A New Option for Games • Core Idea: Two Stages – 1 Transform Linear Data into a Logarithmic color space – 2. Apply LUT to Log data

20. A Filmic Approach to Tone Mapping • Advantages – Distributes Bits Evenly Across Dynamic Range – Darks and Highlights – Encodes Relevant Broad Dynamic Range using Integer Format – Plays Nicely with Modern Hardware – Provides a Broader Range of Control for Art Direction

21. Log Color – Background • Human Visual System – We think of Exposure in Log Terms – Stops are powers of 2 • Film Measurements standard – Density is a Log measure of Intensity – Used for Print and Negative Measurements • Cineon Compositing System – Visual Effects interchange standard

24. Log Color – The Math Linear to Log c = (log10(ln/linReference)/ld*logGamma + logReference)/1023.f; - Conversion is handled easily by Cg and HLSL - Could be sped up by converting to a 16 bit LUT

25. Log Color – The Math Log to Linear c = pow(10, (lg*1023.f–logReference)/ (ld*logGamma))*linReference; - Conversion is handled easily by Cg and HLSL - Could be sped up by converting to a 8 bit LUT • There are a few constants in that equation.

26. Dynamic Range Coverage Comparison • Log – Dynamic Range covered by default parameters: • 0.002 to ~67.5 – Bits per stop using for 8 bit Log with default parameters: • 17 8 bit code values ~ 4 bits – Defaults can be adjust to cover less dynamic range thereby allocating more bits per stop of dynamic range

27. Dynamic Range Coverage Comparison • Gamma – Dynamic Range covered by Gamma/Exponent Approach: • 0 to 1 – Bits per stop using for 8 bit Gamma 2.2 • Average : 24.4 • Max is 69 8. Min is 1.7 = ~ 1 bit. – Decreases for Darker values, where the human visual system is most sensitive – Lifts Black Level

28. Dynamic Range Coverage Comparison An Exponential Ramp – Each Step = 1 Stop - Will appear Linear to the Human Eye - Large range above 1 not shown here

29. Dynamic Range Coverage Comparison A Log Ramp – Each Step = 1 Stop - Represents wide dynamic range consistently - Needs a LUT to prepare for display

30. Dynamic Range Coverage Comparison An Gamma Ramp - Each Step = 1 Stop - Will appear Linear when displayed on a monitor - Will show banding and quantization in the darks - Clamps values above 1

31. Log Color – On Modern Hardware • Allows HDR data to be stored in a LDR integer format • Color Correction can be done quickly in this space • Speculation: This might work equally well on Xenon and PS3 hardware

32. Log Color – Possible Disadvantages • Pow and Log calls may be expensive (?) – Log is cheap. Pow is expensive. – Can be sped up using LUTs • Dynamic Range is fixed, not infinite. – Highlights beyond a certain range will be clipped – Darks beyond a certain range will be clipped • Gamma approach not much better at representing dark detail - ~1 bit • Blending Operations expect Linear data

33. Filmic Tone Mapping • Artistry after the Log Conversion – Starting with Log color data gets you a long way – Simple Authoring pipeline – 1d vs. 3d. LUTs • Short story: Either approach can be used.

34. Filmic Tone Mapping • What makes a LUT “Filmic”? – Linear Middle Section – “Shoulder” – Soft Compression of Highlights – “Toe” – Soft Compression of Darks

60. Tiger Demo • Real time demo using Filmic Tonemapping

61. Thanks for Your Time • Questions?

Filmic Tonemapping - EA 2006

Filmic Tonemapping - EA 2006

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