This document discusses visual perception and the processes of sensation and perception. It defines sensation as the passive process of bringing external information to the brain through the senses. Perception is defined as the active process of selecting, organizing, and interpreting sensory information. The document outlines different approaches to perception, including bottom-up stimulus-driven perception, top-down goal-driven perception based on knowledge and expectations, and interactive perception involving both processes. It also discusses theories of bottom-up perception, object perception from viewer-centered and object-centered perspectives, Gestalt laws of patterns and forms perception, and depth perception.

1. Visual perception
Syed Ali Raza
Lecturer
Department Of Computer Science
GC University Lahore

2. Sensation
Sensations can be defined as the passive process of bringing information from the outside world into the body
and to the brain. The process is passive in the sense that we do not have to be consciously engaging in a "sensing"
process.

3. Perception
Perception can be defined as the active process of selecting, organizing, and interpreting the information
brought to the brain by the senses.

4. Basics of perception

5. Illusion
Seeing things that ARE NOT THERE and ARE THERE

6. Approaches of perception
Bottom-Up (Stimulus- Driven) Perception
Physical characteristics of stimulus drive perception.
Top-Down (Goal-Driven) Perception
Knowledge, expectations, or thoughts influence perception.
Interactive Perception
Perception is driven by both at the same time.

7. Bottom-up perception
 Direct Perception
 Template Theories
 Feature- Matching Theories
 Recognition by Component Theories

8. Direct perception

9. Template theory

10. Feature matching

11. Recognition by component

12. Top-down perception

13. Object perception
Viewer- Centered
Individual stores the way the object looks to him or her.
The shape of the object changes, depending on the angle from which ones look at it. A number of views of the
object are stored, and when ones try to recognize an object, ones have to rotate that object in his/her mind until it
fits one of the stored images.
Object- Centered
Individual stores a representation of the object, independent of its appearance to the viewer.

14. Gestalt law

15. Patterns and forms perception
 Feature Analysis
 Configurationally Analysis

16. Depth perception