Perceiving Form and Perceptual Organisation Flashcards
True or False?
The retina is curved
True
What are unevenly distributed in the eye?
Receptors
Images perceived by the retina have 4 main characteristics. What are they?
1) Inverted
2) Distorted
3) Tiny
4) Flat
True or False?
There’s an even amount of cortex devoted to different parts of the visual field
False
There’s an uneven amount of cortex devoted to different parts of the visual field
What are the 2 approaches to the perception of form and organisation?
1) Marr’s approach
2) Gestalt approach
What is Marr’s approach concerned with?
The representation of edges, contours and other areas of contrast change
What is the Gestalt approach concerned with?
The rules of perceptual organisation
The representation of edges, contours and other areas of contrast change
Which form perception approach is concerned with this?
Marr’s approach
The rules of perceptual organisation
Which form perception approach is concerned with this?
Gestalt approach
Who thought of Marr’s approach?
David Marr
Which form of perception and organisation approach is bottom-up?
Marr’s approach
Which form of perception and organisation approach breaks down the computation between input and producing output between units of perception?
Marr’s approach
Which form of perception and organisation approach starts with input to the perceptual system in the form of a retinal image and describes the stages in processing this image?
Marr’s approach
What happens in each stage of Marr’s approach?
Each stage takes the input information from the previous stage and transforms it into a more complex description or representation of the image
Which form of perception and organisation approach is a computational model?
Marr’s approach
Computational models consist of 3 theories/levels. What are they?
1) Computational theory
2) Algorithmic level
3) Mechanism level
What does the computational theory look for in a model?
- What is the model trying to do?
- What are the processes for?
- What is the goal?
What does the algorithmic level look for in a model?
- What algorithm is needed
- What process is needed in order to recognise objects in the environment
What does the mechanism level look for in a model?
- What mechanism is needed to implement the algorithm?
- How is this mechanically done to perform such algorithms?
Define algorithms
Movements you make to achieve a certain output
How is retinal image analysed as suggested by Marr’s approach?
Sequentially at different levels
List the 5 stages of retinal image analysis according to Marr’s approach
1) Retinal image projected at the back of the eye
2) Grey-level description
3) Primal sketch
4) 2 1/2 D sketch
5) 3D representation
What happens in the grey-level description stage of retinal image analysis according to Marr’s approach?
Measure the intensity of light at each point in the image
What happens in the primal sketch stage of retinal image analysis according to Marr’s approach?
Representation of contrast change (blobs, edges, bars) over a range of spatial frequencies