Contour Detection: Unveiling the Art of Visual Perception in Computer Vision

By Fouad Sabry

What is Contour Detection

Abnormalities in visual processing are frequently observed in people with schizophrenia, and they are a contributing factor to impaired social function.

How you will benefit

(I) Insights, and validations about the following topics:

Chapter 1: Visual processing abnormalities in schizophrenia

Chapter 2: Visual cortex

Chapter 3: Optical illusion

Chapter 4: Magnocellular cell

Chapter 5: Chubb illusion

Chapter 6: Colour centre

Chapter 7: Visual modularity

Chapter 8: Form perception

Chapter 9: Phantom contour

Chapter 10: Sensory memory

(II) Answering the public top questions about contour detection.

(III) Real world examples for the usage of contour detection in many fields.

Who this book is for

Professionals, undergraduate and graduate students, enthusiasts, hobbyists, and those who want to go beyond basic knowledge or information for any kind of Contour Detection.

• Language: English
• Publisher: One Billion Knowledgeable
• Release date: Apr 29, 2024

Book preview

Chapter 1: Visual processing abnormalities in schizophrenia

Abnormalities in visual processing are widespread in schizophrenia and have been linked to impaired social functioning.

The ability to perceive contrast and motion, regulate eye movement, recognize visual outlines, and identify faces or facial expressions may all be impaired in people with schizophrenia. There is still much discussion amongst scientists about the particular causes of numerous visual processing impairments seen in schizophrenia.

The contrast of a visual stimulus is the degree to which dark and light areas are visually differentiated from one another. The contrast sensitivity function characterizes the sensitivity to contrast in sine wave stimuli, which is determined by the stimulus's temporal frequency and spatial frequency features, respectively. Researchers have shown that people with schizophrenia have decreased contrast sensitivity. However, Butler and coworkers disagree with the magnocellular deficit theory, arguing that not enough data exists to support it and that investigations investigating this topic have had highly conflicting results.

Similar to the simultaneous contrast illusion is an effect known as surround suppression (see Figure 1), in which one stimulus' apparent contrast is reduced when another stimulus is shown around it. Perceived contrast in the surrounding environment is estimated to be less repressed in people with schizophrenia than in healthy adults.

Individual neurons are oriented to a preferred direction of motion, and this occurs as early as the first stages of cortical visual processing, making motion perception a crucial visual function. One study found evidence of reduced motion perception and weaker perceptual suppression effects in schizophrenia when they tested the ability to inhibit motion perception by adding a surround stimulus.

Moving one's eyes around is a crucial behavior for finding and following items in one's field of vision. Saccades and smooth pursuit are two of the most common types of eye movement. Saccades, which are quick and precise movements of the eyes between two points, are crucial for establishing fixation. On the other hand, smooth pursuit lets you follow an object as it travels across your field of view. People with schizophrenia have been observed to show deficits in eye movement behavior since the early 20th century. Results from this study showed a correlation between motion perception and smooth pursuit task performance, but no association between smooth pursuit measures and attention.

An essential task in both human and machine vision, edge detection is crucial for figure-ground segmentation and object recognition. The ability to integrate disparate visual inputs into a unified perception is essential for contour perception. In trials testing the ability to build a cohesive perception of a line from disparate visual data, such as a simplified connect the dots puzzle, participants with schizophrenia performed lower than healthy adults. In schizophrenia, problems with visual processing (such flawed contour detection abilities) tend to be mild. As a result, it may be essential to compare large samples of healthy adults to samples of those with schizophrenia using statistical approaches, which requires conducting experiments on a large number of subjects. It has been hypothesized that deficits in NMDA-receptor function contribute to weaker lateral excitation, which in turn may impair brain processing and contribute to the difficulties with contour integration seen in schizophrenia. This fits with the glutamate theory of schizophrenia, which proposes that abnormalities in this neurotransmitter system are responsible for the symptoms typically associated with the disorder.

The impact of flanker or collinear facilitation, in which the presentation of stimuli surrounding a target can increase responses to the target in cortex, is reduced in people with schizophrenia compared to normal adults or those with bipolar disorder. According to them, the