Lecture13

Question 1

What is image analysis primarily concerned with?

Answer 1

Data Reduction

Image analysis transforms images into numerical data representing features of objects.

Question 2

What are the key features of image analysis?

Answer 2

• Features from the image as a whole
• Features from objects in the image
• Handcrafted features
• Deep features

Features classify images or objects in classes, utilizing supervised or unsupervised methods.

Question 3

What is the definition of size?

Answer 3

The quality of an object that determines how much space it occupies

This definition is based on Webster’s dictionary.

Question 4

Who is D’Arcy Thompson and what is his contribution to understanding size?

Answer 4

D’Arcy Thompson wrote ‘On Growth and Form’ in 1917, defining form in relation to magnitude in various directions.

Question 5

What does magnitude refer to?

Answer 5

• A small elephant
• A large rat

Magnitude is used for comparing sizes at different orders.

Question 6

What is the definition of shape?

Answer 6

The quality of an object that depends on the relative position of all points on its surface

This definition is also based on Webster’s dictionary.

Question 7

What aspects are related to size?

Answer 7

• Length
• Area
• Volume
• Density
• Moments

Question 8

What aspects are related to shape?

Answer 8

• Shape factor
• Compactness
• Convexity
• Solidity
• Curvature
• Bending energy
• Moments

Question 9

How is size and shape expressed in imaging?

Answer 9

• Pixels/Voxels
• Imels
• Calibration to metric units

Measurement involves observations like average, variance, and standard deviation.

Question 10

What is surface area and how can it be computed?

Answer 10

Area can be expressed analytically by formulas for different shapes, such as circle and triangle.

Question 11

What is the importance of accurate surface area measurement?

Answer 11

Counting pixels (imels) must be compared with analytical surfaces for accuracy.

Question 12

What is perimeter?

Answer 12

A measure derived from the boundary pixels of an object.

Question 13

What is the difference between 4-connected and 8-connected contours?

Answer 13

4-connected uses a city-block code, while 8-connected uses a chain code.

Question 14

What does convex deficiency measure?

Answer 14

Cd = Area(hull) - Area(object)

Question 15

What is the ratio used to measure solidity?

Answer 15

Aobject / Areahull

Question 16

What does compactness relate to?

Answer 16

A standard shape, specifically a circle.

Question 17

What is roundness and how is it calculated?

Answer 17

Roundness = 4π Aobject / (Phull)²

Question 18

What does sphericity express?

Answer 18

Sphericity = Rinscribed / Rcircumscribed

Question 19

What is curvature in the context of shape analysis?

Answer 19

Curvature is a boundary descriptor representing the rate of change of direction at a point on a curve.

Question 20

What does a positive curvature indicate?

Answer 20

Convex parts of a shape.

Question 21

What does a negative curvature indicate?

Answer 21

Concave parts of a shape.

Question 22

What does curvature provide in relation to shape?

Answer 22

Local shape information.

Curvature indicates the nature of a shape, with convex parts resulting in positive curvatures and concave parts resulting in negative curvatures.

Question 23

What is the relationship between curvature and K-slope?

Answer 23

Curvature is calculated from K-slope.

The formula involves angles and periodic functions.

Question 24

What is the range of total absolute curvature?

Answer 24

1 ≤ TOTAL ≤ ∞, where P is length.

This indicates that total curvature can vary widely based on the shape.

Question 25

What does bending energy Ec represent?

Answer 25

The energy required to bend a rod to the desired shape. ## Footnote It is calculated from curvature values over a boundary length P.

Question 26

What is the minimum bending energy value for a circle?

Answer 26

2π/R, where R is the radius of the circle. ## Footnote This represents the most efficient shape in terms of bending energy.

Question 27

What is a defining characteristic of fractal behavior?

Answer 27

Observed when a measurement is n-1 lower than viewing dimension n. ## Footnote For example, perimeter in 2D and surface in 3D.

Question 28

How does resolution affect the measurement of a rough boundary?

Answer 28

Higher resolution leads to larger measurement results. ## Footnote This is typical for measurements that are one dimension lower than the measurement grid.

Question 29

How is fractal dimension calculated?

Answer 29

D = log(N) / log(r), where N is the measurement and r is the scale. ## Footnote This reflects the relationship between measurement and dimension.

Question 30

What is the Richardson plot used for?

Answer 30

To derive fractal dimension from the slope of a log-log plot. ## Footnote It involves plotting perimeter against width or ruler L.

Question 31

What are moments in the context of image analysis?

Answer 31

Defined as qp m = ∫∫ xy f(x, y) dx dy for continuous case. ## Footnote For discrete cases, it is M = ΣΣ xy F(x, y).

Question 32

What are centralized moments?

Answer 32

Translation invariant moments defined as µpq = (x - x̄)(y - ȳ) F(x, y). ## Footnote Here, x̄ and ȳ are the mean values.

Question 33

What does the zero order moment represent?

Answer 33

The number of points in F(x,y), corresponding to surface area. ## Footnote It counts the total pixel value in a binary image.

Question 34

What is the interpretation of first order moments?

Answer 34

They represent the center of gravity of a binary distribution. ## Footnote This is different for binary versus intensity images.

Question 35

What are normalized moments derived from?

Answer 35

Centralized moments, with first order moments set to zero. ## Footnote Normalized moments are scale invariant.

Question 36

How is the semi-major axis calculated from moments?

Answer 36

1/2 * √(µ20 + µ02 + √((µ20 - µ02)² + 4µ11)). ## Footnote This formula is used to describe the shape of the object.

Question 37

What does the orientation of the major principal axis indicate?

Answer 37

It is the angle of the major axis with respect to the x-axis, given by θ = 1/2 * tan(2µ11 / µ20 - µ02). ## Footnote This is derived from second order central moments.

Question 38

What are moment invariants?

Answer 38

A set of invariants derived from normalized moments (0th to 3rd order). ## Footnote They are rotation and scale invariant.

Question 39

What does the extension measure in shape analysis?

Answer 39

How much the shape differs from a circle, with zero indicating a circular shape. ## Footnote It increases without upper limit as the shape becomes less compact.

Question 40

What is the significance of dispersion in shape analysis?

Answer 40

It indicates the minimum extension that can be attained by uniform compression of the shape. ## Footnote The long axis is the unique axis for this measurement.

Question 41

How is elongation defined?

Answer 41

It measures how much the shape must be compressed along its long axis to minimize extension. ## Footnote Elongation is never less than zero and never greater than extension.

Question 42

What is the average density of a binary object?

Answer 42

1. ## Footnote A binary object serves as a mask for density image calculations.

Question 43

What does the Lambert-Beer law relate to in microscopy?

Answer 43

It relates intensity to concentration and extinction coefficient in a logarithmic form. ## Footnote It allows for the computation of concentration from intensity measurements.

Question 44

What is the purpose of labeling objects in an image?

Answer 44

To select relevant objects and remove irrelevant ones. ## Footnote This step is crucial for accurate measurements in image analysis.

Question 45

What is the assessment method used in Life-Sciences for organisms exposed to environmental factors?

Answer 45

Two-class, Multi-class problem ## Footnote This involves comparing wild-type with experimental phenotypes.

Question 46

What are the main components of the learning process in image analysis?

Answer 46

Learning, Classification, Pattern Recognition ## Footnote These components are essential for prediction from a classifier.

Question 47

Define accuracy in the context of measurements.

Answer 47

Accurate result, close to the true value, no bias ## Footnote Measurements should be taken from a standard calibrated caliper.

Question 48

What is precision in measurements?

Answer 48

Same result after repeated application, reproducibility ## Footnote It reflects the consistency of measurements.

Question 49

What constitutes a valid measurement?

Answer 49

Accurate & Precise ## Footnote Both accuracy and precision are necessary for measurements to be considered valid.

Question 50

List some features that can be evaluated in image analysis.

Answer 50

* Surface Area * Perimeter * Shape, Normalized Features * Curvature * Fractal dimension * Moments, Invariant Features ## Footnote These features help in analyzing the morphology of samples.

Question 51

What is the goal of comparing wild-type with experimental phenotypes?

Answer 51

Select features to differentiate between Wt-phenotype and Exp-phenotype.

Question 52

True or False: A valid measurement can be accurate but not precise.

Answer 52

False ## Footnote A valid measurement must be both accurate and precise.

Question 53

What is the purpose of minimizing bias in measurements?

Answer 53

To ensure accurate results when testing a feature.

Question 54

What is the source of the books mentioned in the acknowledgments?

Answer 54

Gonzales & Woods: Digital Image Processing ## Footnote This book is referenced for foundational knowledge in digital image processing.

Question 55

What is the relationship between accuracy and bias in measurements?

Answer 55

No bias is required for a measurement to be considered accurate.