The direct, non-diffuse lighting creates a strong light reflection on the smooth surface. Light is mainly reflected. Using a point light source, the angle of incidence is the same as the angle of reflection. If the camera observes the reflection from the direction of the angle of incidence, these reflections will be clearly visible in the camera image. This is often problematic, especially with lighting and camera from above.

Image: Strong, localised surface reflection. Light is slightly scattered on scratched surface structures.

Most of the light is reflected from the relatively smooth surface.

Surface treatments (brushing, sandblasting, matting) or an oxide layer on the surface of base metals scatter the light more.

Although a light spot is still clearly visible, it is significantly enlarged compared to fully reflective materials.

Image: Still strong reflections, deeper flaws in the metal or pressure marks lead to tiny shiny spots in the camera image.

The direct, non-diffuse light hits the matt, porous surface and is strongly scattered and reflected in many directions.

Much less light hits the camera system and the image appears much darker. However, there are hardly any disturbing reflections in the image, even when the camera is looking at the object from the direction of the exit angle.

Image: Direct light spot no longer visible due to high scattered light and high reflection. Only the edge shading is visible due to insufficient ring illumination.