and 110 [degrees] from the specular angle
(45 [degrees] ).
The instrument simultaneously measures the reflectance properties at live different angles relative to the specular angle
, 15[degrees], 25[degrees], 45[degrees], 75[degrees], and 110[degrees].
Both shading devices permit direct sunlight to penetrate at the specular angle
A diffused reflection that scatters light is defined as "the process by which incident flux is redirected over a range of angles," whereas a mirror-like "regular (specular) reflection" is "the process by which incident flux is redirected at the specular angle
," according to the IES Handbook.
Pigments with this structure show the traditional chroma reduction in moving from the specular angle
to aspecular angles of illumination and reflection.
In November 2004, a new ISO standard was published for the determination of paper gloss at a specular angle
Tests also revealed larger particles give more color impact at the specular angle
and more lightness at 20[degrees] and 45[degrees].
The customizable parameters include the size and locations of the source and receptor apertures, the specular angle
, the surface orientation, and the reflection model.
On a transparent substrate one color is seen at the specular angle
, another color at the diffuse angle, and a third color is observed by transmission.
In general, gloss is measured only in the specular angle
by the means of a glossmeter.
Figure 12 shows that both pigments have the almost same lightness; however, the chroma value at specular angle
is quite different.
Specular gloss is related to that part of the reflected light that leaves the surface at the specular angle