Brightness of luminance distributions with gradual changes

Area of Science:

• Visual perception
• Psychophysics
• Computational neuroscience

Background:

• Understanding how humans perceive luminance is crucial for fields like display technology and computer vision.
• Previous models often focused on specific luminance changes, like steps or second-order differences.

Purpose of the Study:

• To investigate the perception of gradually changing luminance distributions.
• To determine the contrast threshold at which inner and outer edges of a stimulus are perceived as different.
• To explore how different luminance functions and background configurations influence brightness perception.

Main Methods:

• Subjects viewed stimuli with luminance changing linearly, quadratically, or cubically across a disk's radius.
• Participants adjusted luminances to match the inner and outer edges of the stimuli.
• Contrast thresholds and perceived brightness differences were recorded under varying conditions.

Main Results:

• A consistent contrast threshold of approximately 20% was found for distinguishing inner and outer edge luminances.
• This threshold remained stable regardless of the luminance distribution function (linear, quadratic, cubic).
• Perceived brightness differences increased with greater luminance change magnitude and were influenced by background luminance contrast.

Conclusions:

• Brightness perception models must incorporate the entire luminance distribution, not just localized changes.
• The 20% contrast threshold offers a quantifiable measure for perceptual differences in gradual luminance gradients.
• Background context significantly modulates the perception of luminance differences within a stimulus.