theories of pattern recognition

7/30/2019 Theories of Pattern Recognition

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Theories Of

Pattern Recognition

BY . PRASAD JADHAV


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What exactly a

Pattern

Recognition

is?


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Pattern recognition refers to the

process of recognizing a set of stimuli

arranged in a certain pattern that is

characteristic of that set of stimuli.


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Pattern recognition involves

identification of faces, objects,

words, melodies, etc


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The Gestalt approach.

Gestalt approach is a theory of mind and

brain; the operational principle of gestaltpsychology is that the brain is holistic,

parallel, and analog, with self-organizing

tendencies. The principle maintains that thehuman eye sees objects in their entirety

before perceiving their individual parts.


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Figure - Ground


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Gestalt Approach examples


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Proximity.


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Similarity


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Continuity.


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Closure


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Symmetry.


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Bottom-Up Theories

Template Theories

Prototype Theories

Feature Theories

Structural-Description Theory


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Template Theories

Templates are highly detailed models for

patterns we potentially might recognize.

We recognize a pattern by comparing it

with our set of templates. We then

choose the exact template that perfectlymatches what we observe.


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Chess players who have knowledge of many

games use a matching strategy in line with

template theory to recall previous games


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such theories cannot easilyaccount for our perception

of the letters and words


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Contradiction to template theory

We can recognize anA as anA despite variations in

the size, orientation, and form in which the letter is

written.

Are we to believe that we have mental templates for

each possible size, orientation, and form of a letter?


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Prototype Theories

Prototype means a concept of average characteristics of a

particular subject. It can be found throughout the world.

For instance a concept of small animal with feathers, beak,

two wings that can fly is a prototype concept of a crow,

sparrow, hen, eagle, etc.


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Prototype Theories Example

When a sensory device registers a new stimulus, the devicecompares it with previously stored prototypes. An exact match

is not required; in fact, only an approximate match is expected.


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Feature Theories

According to these theories, we attempt to match features

of a pattern to features stored in memory, rather than to

match a whole pattern to a template or a prototype.


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According to Oliver Selfridges feature-matching model, we recognize patterns by

matching observed features to features already stored in memory. We recognize

the patterns for which we have found the greatest number of matches

Oliver Selfridges feature-matching model


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Top-Down Approaches

Top down processing can be seen as

processing what one is perceiving using pastinformation. It occurs when someone infers

from a generalization, law etc. to conclude

something about a particular example,instance, case etc.


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ST_P


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color constancy

In color constancy, we perceive that the color of an object

remains the same despite changes in lighting that alter the

hue. Consider lighting that becomes so dim that color

sensations are virtually absent.

We still perceive bananas as yellow, plums as purple, and so

on.


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Than

kyou


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Thankyou

theories of pattern recognition

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