Hable — Uncharted 2 Filmic

The Hable tone mapper (also called "Uncharted 2 filmic") is a parametric S-curve developed by John Hable for the game Uncharted 2. Presented at GDC 2010, it gives precise independent control over the toe, linear section, and shoulder through seven parameters plus an exposure bias.

How it works

Partial function:

float3 partial(float3 x)
{
    return ((x*(A*x + C*B) + D*E) / (x*(A*x + B) + D*F)) - E/F;
}

float3 result = partial(color * ExposureBias) / partial(W);

The division by partial(W) normalizes the curve so that the input value W maps exactly to 1.0.

Settings reference

Setting	Default	Description
A — Shoulder Strength	0.15	Controls how the highlights roll off. Higher = more compression in the bright range.
B — Linear Strength	0.50	Gain in the linear section.
C — Linear Angle	0.10	Angle/tilt of the linear section against the toe.
D — Toe Strength	0.20	How aggressive the dark-end compression is.
E — Toe Numerator	0.02	Fine-tunes the toe lift.
F — Toe Denominator	0.30	Controls toe curvature shape.
W — White Point	11.2	Input luminance that maps to display white.
Exposure Bias	2.0	Pre-curve exposure multiplier (not in stops — linear scale).

note

A–F are dimensionless curve shape parameters. The defaults reproduce Hable's original Uncharted 2 settings.

Tuning guide

Making the image brighter overall — Increase Exposure Bias (default is 2.0). This is a linear multiplier, not stops.

Softer highlight roll-off — Reduce A (Shoulder Strength) toward 0.10.

More punch in the shadows — Increase D (Toe Strength) to 0.30–0.40.

Changing the tone range — Adjust W (White Point). Higher values compress a wider HDR range; lower values clip highlights earlier.

When to use Hable

• Action games, AAA-style projects with strong cinematic intent
• When you want filmic contrast without the hue rotation that can occur in AgX
• When you need to match the tone response of a reference from the PS3/X360 generation

Reference

GDC 2010 — "Uncharted 2: HDR Lighting", John Hable. Full presentation and formula details at filmicworlds.com.