🏙️ Image derivative § Continuous § f′(x)=limh→0hf(x+h)−f(x) Discrete § forward difference: Δxf(x)=f(x+1)−f(x) central difference: δxf(x)=f(x+1)−f(x−1) backwards difference: ∇xf(x)=f(x)−f(x−1) Use cases § edge detection 📖 Example §