Instrumental measurements of transparancy that match human perception

 
Ratings of transparency by human perception often will not correlate with the contrast ratio or other single point measures of transparency because multiple factors often combine to contribute not only to the transparency or opacity, but to an angle dependence thereof. Not only is the human perception subjective, but single point measures are often incorrect when closely examined. When more than one value is used or combined to predict transparency, multiple instruments are needed and comparison is difficult. To overcome these quantification and angle dependence issues, transparency has been divided into four optical properties: haze, scatter, bronze and gloss. As measured on a diffuse sphere spectrophotometer the angle dependent, bronze and gloss, and the angle independent, haze and scatter, are determined from the specular included and excluded spectral responses, respectively. When examined closely the values for these four properties accurately compare to the human assessment of transparency for pigmented systems.