- 2076 Chaitra · 2 marks
Phong shading and Mach-band effect
Short answer
Yes, Phong shading interpolates normals rather than intensities, resulting in smooth intensity changes across polygon boundaries. This greatly reduces Mach bands, though not completely, and also correctly renders highlights.
Can we use the Phong shading method to reduce the Mach-band effect?
Yes. Phong shading greatly reduces the Mach-band effect. It interpolates the surface normals, so the normal (and therefore the intensity) changes smoothly across each polygon and from one polygon to the next. As a result, the intensity changes gradually at polygon borders, unlike Gouraud shading, which interpolates intensity linearly and has abrupt changes in slope at the edges. Phong shading does not remove the effect completely, but the result is much smoother, and highlights are also shown correctly. The price is a higher computation cost.
✓ Answer checked by Claude Opus 5.5 (high effort)
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