Gamma Correction Calculator

Enter any two values (input, gamma, or output) into the calculator to determine the missing value. For the calculators on this page, the input and output values are normalized to the range of 0 to 1.

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• Gamma Index Calculator

Gamma Correction Formula

In the “Pure Gamma” (power-law) model, gamma decoding (linearization) and gamma encoding are related by the following equations.

\begin{aligned}
O &= I^{\gamma} \\
I &= O^{1/\gamma}
\end{aligned}

Variables:

• O is the linear-light (decoded) output value (0 to 1)
• I is the gamma-encoded (nonlinear) input value (0 to 1)
• γ (gamma) is the gamma exponent (γ > 0)

To decode/linearize a gamma-encoded value, raise it to the power of γ (O = I^γ). To encode a linear-light value, raise it to the power of 1/γ (I = O^(1/γ)). Note: real standards such as sRGB are not a pure power law across the whole range; use the “sRGB Transfer” tab for the standard piecewise sRGB conversion.

What is Gamma Correction?

Gamma correction is a nonlinear operation used to encode or decode luminance (or tristimulus) values in video and still-image systems. In practice, it is used to convert between linear light (where values are proportional to physical light intensity) and a nonlinear signal representation designed to match display behavior and human visual perception. Depending on direction, gamma correction may mean encoding (applying a 1/γ power) or decoding/linearization (applying a γ power).

How to Calculate Gamma Correction?

The following steps outline how to calculate a gamma conversion using the pure power-law model.

1. Decide whether you are decoding/linearizing (O = I^γ) or encoding (I = O^(1/γ)).
2. Determine the normalized value(s) (I and/or O), each between 0 and 1.
3. Determine the gamma exponent (γ), which should be greater than 0.
4. Use the appropriate formula to calculate the unknown value.
5. Enter the known values into the calculator above to confirm your result.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Input value (I) = 0.5

Gamma (γ) = 2.2

Using the decoding/linearization formula O = I^γ, the output value (O) is calculated as:

O = 0.5^2.2 ≈ 0.218