blendColorDodge: Luminous Highlight Enhancement

Mathematical Foundation of Color Dodge

Color dodge creates brilliant highlight effects by dividing the base color by the inverted blend color. This mathematical approach amplifies luminosity while creating ethereal glow effects reminiscent of photographic overexposure.

The mathematical definition is:

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

The division operation creates non-linear brightening that becomes more pronounced as blend values approach one, generating luminous regions with preserved shadow detail.

Luminosity Enhancement Properties

Property	Description	Visual Effect
Highlight Amplification	Bright areas become brilliantly luminous	Ethereal glow effects
Shadow Preservation	Dark areas maintain detail structure	Selective brightening
Contrast Inversion	Reverses burn effect behavior	Photographic overexposure
Saturation Protection	Prevents color clipping	Stable computation

ライブエディター

const fragment = () => {
      const center = vec2(0.5)
      const dist = uv.sub(center).length()
      const base = vec3(0.2, 0.3, 0.6).mul(
              float(0.5).smoothstep(0.2, dist)
      )
      const lightSpot = float(0.3).smoothstep(0.1, uv.sub(vec2(0.7, 0.3)).length())
      const gradient = uv.x.mul(0.5)
      const dodge = vec3(lightSpot, gradient, lightSpot.mul(gradient))
      const result = blendColorDodgeVec3(base, dodge)
      return vec4(result, 1)
}