## What is a reflectance edge?

Reflectance edge. an edge where the reflectance of the 2 surfaces changes. Illumination edge.

## What is the difference between and illumination edge and a reflectance edge?

If two intersecting edges show luminance ratio invariance, one edge is likely to be an illumination edge or non-reflective transparency, the other a reflectance edge. If the contrast sign changes across two intersecting edges, the edges are both likely to be reflectance edges.

**What is perceptual lightness?**

Richard F. Murray; A model of lightness perception guided by probabilistic assumptions about lighting and reflectance. Lightness perception is the ability to perceive black, white, and gray surface colors in a wide range of lighting conditions and contexts.

### What is reflectance in image processing?

Reflectance is the amount of light reflected by the object in the scene. It is represented by r(x, y).

### What is the unit of reflectance?

Reflectance is the ratio of the amount of light leaving a target to the amount of light striking the target. It has no units.

**How do you calculate reflectivity?**

Reflectivity can be calculated as p(y) = Gr(y)/Gi(y) where p is the reflectivity, y is the wavelength of the light, Gr is the reflected radiation and Gi is the incident radiation. Calculate reflectance from the reflectivity. Reflectance is the square of the reflectivity so q(y) = (Gr(y)/Gi(y))^2.

#### How do you calculate lightness?

Here are 3 ways to calculate Luminance:

- Luminance (standard for certain colour spaces): (0.2126*R + 0.7152*G + 0.0722*B) source.
- Luminance (perceived option 1): (0.299*R + 0.587*G + 0.114*B) source.

#### What is reflectance formula?

Calculate reflectance from the reflectivity. Reflectance is the square of the reflectivity so q(y) = (Gr(y)/Gi(y))^2. where q is the reflectance, y is the wavelength of the light, Gr is the reflected radiation and Gi is the incident radiation.

**How do you calculate reflectance value?**

This contrast is calculated using the following formula: (B1 – B2) x 100 / B1, where B1 and B2 are the LRV of the lighter area and darker area, respectively. The LRV can be obtained using the CIE Y values measured under the illuminant D65 (natural daylight) and 10° observer.