Michelson Contrast Haze MCH

MCH (Michelson Contrast Haze) is a visual haze parameter that quantifies the loss of contrast between the specular highlight and its surrounding area using the Michelson contrast formula, closely matching how hazy the surface appears to the eye.

Parameter description

MCH describes how much the halo around the specular highlight reduces the contrast between bright and dark regions in the reflected image. A low MCH value indicates a sharp, well‑defined highlight with high contrast, while a higher MCH value indicates a hazier surface with a broader, more washed‑out highlight.

How is it measured?

The instrument captures a high‑dynamic‑range image of the gloss highlight and the neighbouring background at the 60° geometry.

image description

Michelson contrast is calculated from the luminance of the bright highlight region and the adjacent darker region, and this contrast value is converted into the MCH haze scale used for reporting and comparison.

Applications

Characterising visual haze on high‑gloss coatings where small differences in haze and contrast are seen by observers but not well captured by traditional haze scales.

Setting appearance limits and monitoring production for premium automotive, electronics and decorative finishes, ensuring that perceived haze remains within acceptable visual tolerances.