Visual Gloss

Visual Gloss (VGU): Refers to the subjective perception of glossiness as experienced by human observers.

Gloss perception of high gloss surfaces is influenced not only by the intensity of the specular highlight but also the background colour of the material it is reflected in.

^{Materials with a dark background appear glossier to a human observer than the same amount of reflection on a material with a white background. This image shows the difference between standard gloss and visual gloss on a dark blue, grey and white car with identical clear coat.}

Visual Gloss Scale

The scale for Visual Gloss (VGU) was obtained through psychophysical experiments where human observers rated the glossiness of various samples under controlled lighting conditions. Experiments involved a light booth with adjustable specular and background light sources, and samples with different back painted colours and various gloss levels.
Observers used a method called magnitude estimation to assess the glossiness of each sample, comparing them to a standard reference with a predefined gloss value.

Visual Gloss and Human Perception

The VGU equation was derived from the psychophysical experiments showed a high degree of correlation with human perception of gloss, the equation predicts visual gloss (VG) based on the contrast between the brightness of the reflected image against the background colour of the surface.
The performance of the Visual Gloss prediction formula was evaluated using a psychophysical scaling function, and it achieved a high adjusted coefficient of determination (r2 =0.963).

Visual Gloss Measurement

The Aesthetix measures Visual Gloss (VGU) using dual cameras and a combination of light sources, images of the sample are captured under direct illumination by the specular source and background illumination provided by a 45 degree circumferential ring light. The visual gloss algorithm calculates considers intensity of the specular highlight viewed against the luminance of the background viewed in indoor conditions.

^{The Rhopoint Aesthetix measures Visual gloss with images from the specular and observer camera.}

Visual Gloss Validated

The Aesthetix method for calculating visual gloss was validated using an Imaging Luminance Measurement Device (ILMD), mathematical modelling and ray-tracing simulations. Results were empirical tested using diverse samples from a commercial gloss scale.

This validation demonstrated a strong correlation between the Aesthetix measurements and the contrast gloss formula, particularly effective in mid to high gloss ranges.

When to use Visual Gloss VGU compared to Standard Gloss GU

Visual gloss is better suited for applications where human perception is crucial, standard gloss is useful when compliance to a standard is key or measurements need to match historic specifications. Balancing between these two methods can be essential depending on the specific requirements of the project or product

Measurement tip-When Visual Gloss is important

Subjective Perception is Key: If the goal is to understand how people perceive the glossiness of a surface under real-world conditions, VG is more appropriate. This is crucial in industries where the aesthetic and visual appeal are critical, such as in automotive finishes, furniture, consumer electronics, and interior design. Both measurements are visible simultaneously in Rhopoint Appearance Elements software.

Product Development and Marketing: When developing products where the consumer's perception influences their decision to purchase, VG can provide insights into how potential buyers might view the product under typical use conditions.

Quality Control: If the product quality is judged visually by consumers, VG assessments can help ensure consistency in how products are perceived in the marketplace.

Last modified: 31 July 2024