The perceived orientation of aliased lines

Area of Science:

• Computer Vision
• Human-Computer Interaction
• Visual Perception

Background:

• Raster display devices can produce aliasing artifacts, affecting the visual representation of lines and edges.
• Aliasing can be problematic in psychophysical studies, particularly those investigating the perception of stimulus orientation.
• Understanding how aliasing impacts perceived orientation is crucial for accurate visual stimulus design.

Purpose of the Study:

• To assess the perceived orientation of aliased lines.
• To compare the perceived orientation of aliased lines with a computational model.
• To investigate the impact of aliasing on orientational acuity.

Main Methods:

• Subjects were presented with aliased lines generated by raster displays.
• Perceived orientation was assessed by comparing aliased lines with pairs of dots.
• A least-squares metric was applied to the pixels forming the lines to model perceived orientation.

Main Results:

• The perceived orientation of aliased lines is well-modeled by a least-squares metric of the constituent pixels.
• Small deviations from the least-squares model were observed for both aliased and anti-aliased lines.
• These deviations appear to be related to range effects in perception.

Conclusions:

• A least-squares pixel metric provides a robust model for the perceived orientation of aliased lines.
• Range effects can introduce minor perceptual deviations, even with anti-aliased lines.
• Orientational acuity is only slightly reduced when viewing aliased lines compared to ideal lines.