White Balance Node

Description

Adjusts the temperature and tint of input In by the amount of inputs Temperature and Tint respectively. Temperature has the effect of shifting the values towards yellow or blue. Tint has the effect of shifting towards pink or green.

Ports

Name	Direction	Type	Binding	Description
In	Input	Vector 3	None	Input value
Temperature	Input	Vector 1	None	Temperature offset value
Tint	Input	Vector 1	None	Tint offset value
Out	Output	Vector 3	None	Output value

Generated Code Example

The following example code represents one possible outcome of this node.

void Unity_WhiteBalance_float(float3 In, float Temperature, float Tint, out float3 Out)
{
    // Range ~[-1.67;1.67] works best
    float t1 = Temperature * 10 / 6;
    float t2 = Tint * 10 / 6;

    // Get the CIE xy chromaticity of the reference white point.
    // Note: 0.31271 = x value on the D65 white point
    float x = 0.31271 - t1 * (t1 < 0 ? 0.1 : 0.05);
    float standardIlluminantY = 2.87 * x - 3 * x * x - 0.27509507;
    float y = standardIlluminantY + t2 * 0.05;

    // Calculate the coefficients in the LMS space.
    float3 w1 = float3(0.949237, 1.03542, 1.08728); // D65 white point

    // CIExyToLMS
    float Y = 1;
    float X = Y * x / y;
    float Z = Y * (1 - x - y) / y;
    float L = 0.7328 * X + 0.4296 * Y - 0.1624 * Z;
    float M = -0.7036 * X + 1.6975 * Y + 0.0061 * Z;
    float S = 0.0030 * X + 0.0136 * Y + 0.9834 * Z;
    float3 w2 = float3(L, M, S);

    float3 balance = float3(w1.x / w2.x, w1.y / w2.y, w1.z / w2.z);

    float3x3 LIN_2_LMS_MAT = {
        3.90405e-1, 5.49941e-1, 8.92632e-3,
        7.08416e-2, 9.63172e-1, 1.35775e-3,
        2.31082e-2, 1.28021e-1, 9.36245e-1
    };

    float3x3 LMS_2_LIN_MAT = {
        2.85847e+0, -1.62879e+0, -2.48910e-2,
        -2.10182e-1,  1.15820e+0,  3.24281e-4,
        -4.18120e-2, -1.18169e-1,  1.06867e+0
    };

    float3 lms = mul(LIN_2_LMS_MAT, In);
    lms *= balance;
    Out = mul(LMS_2_LIN_MAT, lms);
}