blendColorBurn: Dramatic Shadow Enhancement

Mathematical Foundation of Color Burn

Color burn creates dramatic darkening effects by inverting the blend color and dividing the base by the inverted blend. This mathematical approach intensifies shadows while preserving highlights, creating high-contrast artistic effects.

The mathematical definition is:

$$C_{result} = \begin{cases} 0 & \text{if } C_{blend} = 0 \\ \max\left(0, 1 - \frac{1 - C_{base}}{C_{blend}}\right) & \text{otherwise} \end{cases}$$

The division operation creates non-linear darkening that becomes more pronounced as blend values approach zero, generating deep shadow regions with preserved detail.

Shadow Enhancement Properties

Property	Description	Visual Effect
Shadow Amplification	Dark areas become dramatically darker	Deep, rich shadows
Highlight Preservation	Bright areas maintain luminosity	Selective darkening
Contrast Enhancement	Increases overall dynamic range	Dramatic tonal separation
Zero Protection	Prevents division by zero	Stable computation

ライブエディター

const fragment = () => {
      const center = vec2(0.5)
      const angle = uv.y.sub(center.y).atan2(uv.x.sub(center.x))
      const radius = uv.sub(center).length()
      const base = vec3(
              radius.mul(20).sin().mul(0.3).add(0.7),
              angle.mul(3).cos().mul(0.2).add(0.6),
              radius.mul(1.5)
      )
      const burn = vec3(
              float(0.2).smoothstep(0.8, uv.x),
              float(0.1).smoothstep(0.9, uv.y),
              uv.x.add(uv.y).mul(8).sin().mul(0.3).add(0.4)
      )
      const result = blendColorBurnVec3(base, burn)
      return vec4(result, 1)
}