Lecture10 Flashcards
(140 cards)
1
Q
What is the skeleton in the context of shape representation?
A
The skeleton is a descriptor of the shape and preserves important topology.
2
Q
What is the Euler number of normal shapes related to?
A
The Euler number of normal shapes should be the same as that of a skeleton.
3
Q
What are the types of points associated with a skeleton?
A
- Skeleton points
- End points
- Branch points
4
Q
What is the thickness of a skeleton line?
A
One pixel thick.
5
Q
What method is used to compute the skeleton while preserving topology?
A
Thinning, a repetitive kind of erosion with boundary conditions.
6
Q
What is the purpose of the distance transform in skeletonization?
A
To find the local maxima, which are the skeleton.
7
Q
What is the difference between the Hilda skeleton and the distance skeleton?
A
The Hilda skeleton preserves topology, while the distance skeleton derives from the distance transformation.
希尔达骨架保留了拓扑结构，而距离骨架则源自距离变换。
8
Q
How can a shape be reconstructed from its skeleton?
A
By using the distance to the nearest background pixel as a radius to draw circles.
9
Q
What is thinning in image processing?
A
A subtraction of a hit and miss transform applied to an image to achieve a one pixel thick line.
10
Q
What is a hit and miss transformation?
A
A method that uses structuring elements to find specific patterns in an image.
11
Q
What are the characteristics of normal skeleton points?
A
Normal skeleton points have two neighbors.
12
Q
What defines an end point in a skeleton?
A
An end point has only one neighbor.
13
Q
What defines a branch point in a skeleton?
A
A branch point has three neighbors.
14
Q
How are special points in skeletonization identified?
A
Using hit and miss transformations.
15
Q
What is the limitation of thinning on a grid?
A
It may not result in a one pixel thick line and can break topology.
16
Q
What is the relationship between the distance transform and Voronoi diagrams?
A
The distance transform is a discrete counterpart of the Voronoi diagram.
17
Q
What is the effect of removing a pixel in certain cases during thinning?
A
It can disrupt the topology if the removal breaks continuity.
18
Q
What are pathological cases in thinning?
什么是变薄的病理情况？
A
Situations where thinning cannot be performed without breaking topology.
在不破坏拓扑结构的情况下无法进行减薄。
19
Q
What is the significance of the maximum in the distance transform?
A
It indicates the skeleton’s location.
20
Q
Fill in the blank: The skeletonization process aims to produce a _______ representation of a shape.
A
minimal
21
Q
True or False: The skeleton can be used to match objects by minimizing the number of points to compare.
A
True
22
Q
What is the role of structuring elements in hit and miss transformations?
A
They define the pattern to be matched in the binary image.
23
Q
What happens to the Euler number during skeletonization?
A
It remains the same as in the original shape.
24
Q
What are the basic components of a structuring element in thinning?
A
Zeros and ones.
25
How many basic structuring elements are used in hit and miss transformations?
Eight.
26
What is the process of erosion in the context of skeletonization?
A repetitive subtraction that maintains topology.
27
What do the terms 'skeleton points', 'end points', and 'branch points' refer to?
Different types of points identified in the skeleton of a shape.
28
What is the watershed transformation used for?
It is useful for understanding image segmentation and object separation.
29
What are the two kinds of applications of the watershed transformation mentioned?
It is useful for understanding image segmentation and object separation.
30
What are the two mathematical morphology operations related to the skeleton?
1. Thinning
2. Thickening
31
What is the exoskeleton in the context of image processing?
什么是图像处理中的外骨骼？
The skeleton of the background
## Footnote
It represents the skeletal influential zone.
它代表着骨骼影响区。
32
What does the distance transform reveal about an object's background?
It shows higher distances in dark areas of the background.
33
What is the relationship between watersheds and topological features in images?
Watersheds separate regions based on elevation and gray value landscapes.
34
What is a catchment basin in the context of watershed transformation?
A region where water collects, corresponding to local minima in an image.
35
True or False: Watersheds are local maxima in an image.
False
36
What happens when water is poured into a watershed image?
It overflows into the local minima, forming catchment basins.
37
How can over-segmentation be prevented when applying watershed transformation?
By smoothing the image before applying watershed.
在应用分水岭之前对图像进行平滑处理。
38
What is the significance of erecting dams in the watershed transformation process?
Dams prevent overflow at local maxima, defining the watershed lines.
39
What is meant by the 'influential zone' of a local minimum?
The area surrounding a local minimum where points are attracted to that minimum.
40
Fill in the blank: The maximum value of a pixel in an 8-bit image is _______.
255
41
What is the purpose of the distance transform in identifying objects?
To find local maxima and minima for segmentation.
42
What is the ultimate eroded point in an object?
Characteristic points that define the object's shape.
43
How does the distance transform help in separating clustered cells?
距离变换如何帮助分离聚类单元格？
By identifying local maxima and allowing segmentation based on those points.
44
What is watershed-based clustering?
Applying watershed transformation to segment objects within a labeled basin.
45
What is the primary challenge when segmenting fluorescent cells?
High density range and varying responses to fluorescence.
高密度范围和对荧光的不同反应。
46
What happens if local minima are not well-defined in an image?
It can lead to over-segmentation.
47
What does the term 'homogeneous' refer to in the context of catchment basins?
在集水盆地中，"均质 "一词指的是什么？
Regions where pixel values are similar.
48
What is the purpose of watershed transformation?
To transform an image into an image with only catchment bays and watersheds.
将图像转换为只有汇水湾和流域的图像。
49
What are the two applications of watershed segmentation mentioned?
* Divide the space * Divide the object
50
What are the components of a linear spatial transformation?
* Translations * Rotations * Scaling * Shearing * Mirroring
51
What is the pivotal point in rotation transformations?
旋转变换的关键点是什么？
The point about which the image is rotated.
52
What happens during a translation transformation?
The image is shifted by a specified vector.
53
What is the effect of a clockwise rotation on coordinates?
The new x and y coordinates are calculated using cosine and sine functions.
54
What do we need to consider when transforming coordinates that are not grid points?
Interpolation.
55
What is the result of scaling an image?
The x and y coordinates are multiplied by a scaling factor.
56
What is the difference between shearing and scaling?
Shearing changes the shape of the object without preserving angles, while scaling preserves the shape.
57
What is a rigid transformation?
A transformation that consists only of rotation and translation.
58
What remains unchanged in a rigid transformation?
The shape of the object.
59
What is the general form of an affine transformation?
仿射变换的一般形式是什么？
It involves transforming a point (x, y) to a new point (u, v) using a transformation matrix.
60
True or False: In a rubber sheet transformation, parallel lines remain parallel.
False.
61
What is the mathematical operation used to apply an affine transformation?
Matrix multiplication.
62
What must be done if the scaling results in non-grid points?
Interpolation must be applied.
63
What happens when an image is rotated and scaled larger than its original size?
Information may be lost if the image size is not adapted.
64
What is the purpose of using a transformation matrix in image processing?
To systematically apply transformations to points in the image.
65
What is a common approach when performing transformations on images that need to match in orientation or scale?
Using spatial transformations to make them comparable.
66
What does the term 'distance transform' refer to in image processing?
A method used to separate objects in an image.
67
What is a polar transformation?
A polar transformation is a method where an image is transformed according to polar coordinates, sampling values based on the distance from a pole and an angle.
## Footnote
Polar transformations often result in sub-pixel values and require interpolation techniques.
68
What coordinate systems are compared in the discussion?
Cartesian coordinate system and polar coordinate system.
## Footnote
The Cartesian system uses x and y coordinates, while the polar system uses radius and angle.
69
What happens to parallel lines in polar transformations?
Parallel lines do not remain parallel in polar transformations.
## Footnote
This is a significant difference compared to linear transformations.
70
How does sampling density change in polar transformations?
Sampling density decreases as you move further from the pole.
## Footnote
This results in larger cells requiring more information for interpolation.
71
What is a rubber sheet transformation?
A rubber sheet transformation is a nonlinear mapping that can distort an image by stretching or compressing parts of it.
## Footnote
This transformation can result in non-grid points and altered relative distances.
橡皮布变换是一种非线性映射，它可以通过拉伸或压缩图像的某些部分来扭曲图像。
##脚注
这种变换会导致非网格点和相对距离的改变。
72
What is the purpose of inverse mapping in transformations?
Inverse mapping is used to determine the original point from a transformed point to correctly assign intensity values.
## Footnote
This involves calculating the inverse of the transformation matrix.
73
What are the methods of interpolation mentioned?
Nearest neighbor interpolation, bilinear interpolation, and cubic interpolation.
## Footnote
Nearest neighbor is the simplest method, while bilinear and cubic interpolations provide more accurate results.
74
What is bilinear interpolation?
Bilinear interpolation uses the four nearest grid points to compute a weighted average for a new point's intensity value.
## Footnote
The weights are based on the distances from the new point to the four surrounding points.
75
What is the significance of the weights in interpolation?
The weights in interpolation always sum up to one.
## Footnote
This ensures that the calculated intensity value is a proper average of the surrounding points.
76
Fill in the blank: In polar coordinates, the point is defined by its _______ and _______.
radius, angle.
77
What is dynamic programming's role in polar transformations?
Dynamic programming is used to optimize the polar resampling process and find optimal paths in transformations.
## Footnote
This technique is particularly useful for determining boundaries in images.
78
What is the purpose of inverse mapping in image processing?
To find the original point in XY space that corresponds to a value in UV space.
79
What is bicubic interpolation?
A complex interpolation method that considers multiple values, often using a 4x4 grid.
80
What types of functions can be used in bicubic interpolation?
* Spline functions
* Pure cubic functions
* Other interpolation functions
81
What is the main difference between bilinear and bicubic interpolation?
Bilinear interpolation is straightforward, while bicubic interpolation is dependent on the interpolation function used.
82
What is the goal of image registration?
To align two images and check their similarity.
83
What is a similarity feature in image registration?
A criterion used to assess how similar two images are.
84
What techniques can be used to find a transformation for image registration?
* Control points
* Least squares approach
* Affine transformation
* Polynomial fitting
85
What is the difference between affine transformation and polynomial fitting?
Affine transformation is linear, while polynomial fitting is nonlinear.
86
What is a checkerboard display used for in image registration?
To visualize and assess the fit between images.
87
What is realignment in the context of image registration?
88
What is the role of distance transformations in registration?
To optimize the transformation matrix based on distance criteria.
89
What is a chamfer distance transform?
A method used to calculate distances in edge models for matching images.
90
Fill in the blank: Bicubic interpolation takes into account values from a _______ grid.
4x4
91
True or False: Registration only involves linear transformations.
False
92
What is the purpose of using control points in image registration?
To define a transformation matrix based on identified matching points.
93
What is the expected outcome of successful image registration?
A well-aligned image that accurately represents the same features as the reference image.
94
How does realignment differ from traditional registration?
Realignment considers additional layers above and below to maintain the original shape.
95
What is the significance of using the most significant bit in image overlay?
To ensure that the critical information is prioritized in alignment adjustments.
96
What method can be used to visualize the differences after transformation?
Subtraction of the transformed images.
97
What is the primary goal when aligning consecutive images?
To build a coherent 3D model.
98
What is the primary goal of minimizing root mean square distance?
To achieve a minimal root mean square distance between two contours.
99
In the context of satellite imagery, what is the purpose of bringing models into correspondence?
To compare a model of the earth with a satellite image.
100
What is a resolution pyramid used for?
To quickly find an optimum in translations, rotation, and scaling by sub-sampling the image.
101
What transformation sequence is determined during the image registration process?
A sequence of affined transformations.
102
What does the term 'Euclidean distance transformation' refer to?
A method of measuring distance using Euclidean geometry.
103
Fill in the blank: The _______ coefficient is often used to measure overlap in image registration.
dice
104
What does a low entropy between joint histograms indicate?
That the images are in register with minimal difference.
105
What is the purpose of watershed transformation in image processing?
To separate touching objects in an image.
106
How does the propagation method work for finding connections in an image?
传播法是如何在图像中找到连接点的？
It uses a structuring element to walk along the border and find connected components.
107
What is the function of a seed in the context of image segmentation?
To initiate the propagation process in the segmentation of objects.
108
What does labeling in image processing allow us to do?
To identify and analyze separate objects in an image.
109
What is the significance of using z4 or z8 connectivity in image processing?
To determine how neighboring pixels are connected.
110
True or False: The exclusive OR operation is equivalent to binary subtraction in image processing.
True.
111
What is the outcome of the watershed transformation regarding border elements?
It identifies and connects only those elements that are connected to the border.
112
What measures are used to evaluate the goodness of fit in image registration?
* Root mean square error
* Overlap measures
* Dice coefficient
* Correlation
* Hausdorff distance
113
Fill in the blank: A _______ is used to scan the image for connected components.
structuring element
114
What type of images is typically analyzed using gray value images?
Binary images.
115
What is the main challenge when separating objects in image analysis?
Managing objects that touch the border.
116
What is realignment in the context of image registration?
什么是图像配准中的重新配准？
Realignment refers to the process of adjusting images so that they accurately overlap and correspond with one another.
重新对齐是指调整图像，使其准确重叠并相互对应的过程。
117
What is the primary goal of realignment in image registration?
To ensure that multiple images are accurately aligned for comparative analysis.
118
Fill in the blank: Realignment is often used in _________ to improve the accuracy of image analysis.
medical imaging
119
Which of the following techniques is commonly used for image realignment?
Affine transformation
120
True or False: Realignment can help reduce the effects of motion artifacts in imaging.
真或假： 对齐有助于减少成像中运动伪影的影响。
True
121
What is the difference between realignment and image registration?
Realignment is a step within the broader process of image registration.
重新配准是更广泛的图像配准过程中的一个步骤。
122
Name one application of realignment in the medical field.
Functional MRI analysis
123
What mathematical methods are frequently used in realignment processes?
Interpolation and transformation algorithms
124
Multiple choice: Which of the following is NOT a type of image registration? A) Rigid B) Non-rigid C) Linear D) Circular
D) Circular
125
What role does pixel intensity play in the realignment process?
像素强度在调整过程中起什么作用？
Pixel intensity is used to assess the similarity between images for alignment.
像素强度用于评估图像之间的相似性，以便进行配准。
126
True or False: Realignment can only be performed on images taken from the same viewpoint.
False
127
What is a common challenge faced during realignment?
Dealing with varying image resolutions and perspectives.
128
Fill in the blank: Realignment can be performed using _________ algorithms to minimize error.
optimization
129
What is the significance of control points in realignment?
Control points help define the geometric transformation needed for alignment.
130
True or False: Realignment has no effect on the quality of the final registered image.
False
131
Which type of image registration is typically used for realignment in dynamic imaging?
Temporal registration
132
What is the first step in the realignment process?
Identifying and selecting reference images.
133
Fill in the blank: The output of realignment is a set of _________ images that are spatially coherent.
aligned
134
What is the purpose of using a reference image in realignment?
To provide a baseline for aligning all other images.
135
Multiple choice: Which of the following factors does NOT affect realignment accuracy? A) Image noise B) Illumination changes C) Image compression D) Image color
D) Image color
136
What is the role of software in the realignment process?
Software automates the alignment process and applies algorithms for accuracy.
137
True or False: Realignment is a one-time process that does not require adjustments.
False
138
What is the impact of motion during image acquisition on realignment?
Motion can cause misalignment that realignment aims to correct.
139
Fill in the blank: Realignment is crucial for enhancing the _________ of image-based studies.
reliability
140
What are the two main types of transformations used in realignment?
Rigid and non-rigid transformations.
