Lesson 4 Flashcards
What is morphological image processing?
A tool for extracting image components used to represent the region shape (e.g. boundaries)
Based on mathematical morphology
What are morphological operations based on?
Set theory and logic operations
Define a structuring element (SE).
A small shape or set to probe the image under study, adapted to geometric properties of objects
What does binary dilation do?
Grows (thickens) objects in a binary image
What is the effect of binary erosion on an image?
Erodes away the boundaries of regions of foreground pixels, shrinking areas and enlarging holes
What is the convolution theorem in image processing?
Convolution in an image domain is equivalent to simple multiplication in the frequency domain
What does the Fourier transform allow in image analysis?
Transforms an image into the frequency domain
What is the primary use of the Hough transform in image analysis?
To detect shapes, such as lines and circles, in images
Fill in the blank: Morphological operations are used to describe and apply _______ for image analysis.
morphological operations
What are the two main types of morphological operations?
Dilation and erosion
What does the term ‘set theory operations’ refer to in the context of image processing?
Operations such as union, intersection, and complement that are foundational for morphological operations
What is the main purpose of using existing functions and software packages like scikit-image?
To automatically analyze images
What is the relationship between dilation and erosion?
Dilation and erosion are duals of each other with respect to set complementation and reflection
What is the role of the Fourier transform in filtering images?
Allows for frequency domain manipulation to filter images
What is a key outcome of applying binary opening?
An erosion followed by a dilation
What does the term ‘magnitude’ refer to in the context of the Fourier transform?
The amplitude of the frequency components in an image
What is the difference between convolution and multiplication in image processing?
Convolution is slow to compute, while multiplication is fast
What does the term ‘top hat operations’ refer to in image analysis?
A morphological operation that extracts small elements from larger ones
What is the significance of the image size (M and N) in the Fourier transform?
They define the dimensions of the image in the frequency domain
In morphological image processing, what effect does the structuring element have?
Controls the shape and size of the objects being processed
What is the purpose of implementing solutions to real-world image analysis problems?
To improve tasks such as contrast enhancement and object counting
True or False: The Fourier transform can only represent spatial domain information.
False
What is a practical application of image erosion?
Separates touching objects in an image
What is the basis for morphological operations?
Set theory operations
What is binary opening?
An erosion followed by a dilation.
What is the result of binary opening?
Result of Binary Opening (Erosion + Dilation)
What is binary closing?
A dilation followed by an erosion.
What is the result of binary closing?
Result of Binary Closing (Dilation + Erosion)
What is the application of the opening operation?
Often performed to clear an image of noise whilst retaining the original object size.
What does the closing operation do?
Used to fill holes in a region whilst retaining the original object size.
Fill in the blank: The opening operation tends to ______ the sharp peninsular projections on the object.
flatten
What is a structuring element in morphological operations?
A shape used to probe and transform the input image.
How does the opening operation affect small bright spots?
It can remove small bright spots (i.e., ‘salt’).
What happens during a dilation operation?
The size of the object in the image increases.
What happens during an erosion operation?
The size of the object in the image decreases.
What is the purpose of grayscale morphology?
To extend binary morphological operations to grayscale images using min and max operations.
True or False: The closing operation can connect small light cracks.
True
What is the result of applying grayscale dilation?
The white boundary of the image thickens.
What occurs during the closing operation on grayscale images?
Ellipses at the bottom get connected because of dilation.
Fill in the blank: The elementary binary morphological operations can be extended to grayscale images through the use of ______ and ______ operations.
min, max
What does a hit-and-miss structuring element involve?
It has pixels of 3 values: 0, 1, and ‘don’t care’.
What is a basic morphological smoothing operation?
An opening followed by a closing operation.
What is the white top-hat transformation?
Original image minus its opening.
What does the black top-hat transformation return?
Returns the dark spots of the image that are smaller than the structuring element.
What is the primary goal of morphological operations?
To process images based on their shapes.
Fill in the blank: The closing operation tends to fill the ‘______’ on the edge of a region.
bays
What is the purpose of the closing operation in image processing?
It removes both bright and dark artifacts of noise.
What does the White Top-hat transformation return?
The bright spots of the image that are smaller than the structuring element.
What does the Black Top-hat transformation return?
The dark spots of the image that are smaller than the structuring element.
What is one of the principal applications of the White and Black Top-hat transformations?
Removing objects from an image using a structuring element.
Fill in the blank: The White Top-hat transformation is calculated as the original image minus its _______.
opening
Fill in the blank: The Black Top-hat transformation is calculated as the closing minus the _______.
original image
What does the function skimage.morphology.label do?
It labels connected components in a binary image.
True or False: Two pixels are considered connected if they share a common vertex.
True
What are the two types of connectivity mentioned in connected components?
- 4 connectivity
- 8 connectivity
What does thinning do in image processing?
It removes selected foreground pixels.
What is the result of the thinning operation?
It reduces the foreground regions in a binary image to a skeleton.
What is the skeleton in the context of image processing?
It is the loci of centers of bi-tangent circles that fit entirely within the foreground region.
Fill in the blank: The medial axis is the set of all points having more than one _______ on the object’s boundary.
closest point
What does the function medial_axis return in addition to the medial axis?
The distance transform.
True or False: Skeletonization retains the size of the input object.
True
What is the main difference between thinning and skeletonization?
Thinning reduces the object to a 1-pixel wide representation, while skeletonization retains the size.
What is the purpose of the structuring element in morphological operations?
It defines the neighborhood used to process the image.
Fill in the blank: The structuring element has pixels of 3 values: 0, 1, and _______.
Don’t care
What is the effect of a structuring element with a value of 1?
The corresponding pixel must be 1.
What is the effect of a structuring element with a value of 0?
The corresponding pixel must be 0.
