Displays And Image Processing Flashcards
What does the term ‘Bistable’ refer to?
A system with two stable states, often representing black and white in images.
Define ‘Contrast’ in the context of image processing.
The difference in brightness between the lightest and darkest parts of an image.
What is ‘Brightness’ in image processing?
Determines the brilliance of the displayed image.
What does a ‘Scan Converter’ do?
Translates information from pulse format into video format.
How are images composed in a bistable system?
Images are composed of only 2 shades: black and white.
Differentiate between Analog Numbers and Digital Numbers.
Analog numbers are unlimited and continuous, while digital numbers have discrete values.
What are ‘Electrons’ in the context of an analog scan converter?
Charged particles that contain image information and are shot out to create the image.
What is meant by ‘High contrast’?
A significant difference in brightness levels in an image.
What is a ‘Dielectric matrix’?
A component of an analog scan converter that stores electrons.
Define ‘Pixel Density’.
The number of picture elements per inch.
What is a ‘Bit’?
The smallest amount of computer memory, having a value of either 0 or 1.
What is a ‘Word’ in computer terminology?
A group of bits, typically representing a series of 0s and 1s.
What is a ‘Byte’?
A group of eight bits of computer memory.
What does ‘Analog’ refer to?
An unlimited and continuous range of real-world numbers.
What does ‘Digital’ refer to?
Data represented by discrete values, typically in 0s and 1s.
What is an ‘A-to-D’ Converter?
Analog-to-digital converter that converts electrical signals into digital form.
What is ‘Spatial resolution’?
Image detail determined by the number of pixels.
Define ‘Pixel’.
The smallest building block of a digital picture, representing a single shade of gray.
What is ‘Preprocessing’?
Any process of the reflected signals before storage, controlled by the sonographer.
What is ‘Postprocessing’?
Any process after storage in the digital scan converter that can be reversed.
What does a ‘D-to-A’ Converter do?
Translates digital signals back into analog form for display.
What is ‘Magnification’ in image processing?
Zoom or enlargement of a portion of the image to fill the entire screen.
What does ‘ROI’ stand for?
Region of Interest, the selected part of the image.
Fill in the blank: Grayscale determines the range of _______ within the displayed image.
[brilliancies (shades of gray)]
True or False: Low contrast images have a significant difference in brightness.
False
What does the term ‘Grayscale’ refer to?
Assigns different gray shades to different echo amplitudes.
What is ‘Storage of image data’ referred to as?
‘Writing’ image data.
What is ‘Reading’ in the context of image data?
Displaying image data after it has been stored.
What is Magnification?
The process of enlarging an image to improve visualization
Magnification can occur during data acquisition or post-processing.
Define Coded Excitation.
A sophisticated method to improve image quality by creating long sound pulses with a wide range of frequencies
Keeps peak intensity below FDA limits and improves resolution.
What is Spatial Compounding?
Combining multiple frames from different angles to create a single real-time image
Requires electronic beam steering and is only available with phased array transducers.
What does Edge Enhancement do?
Increases image contrast around edges to make them appear more defined
Creates subtle bright and dark highlights on either side of boundaries.
What is Temporal Compounding?
An image processing technique that displays a view with a history from earlier frames
Reduces noise and improves image quality but lowers frame rate.
Fill-in the blank: The method of image processing that predicts gray scale levels from neighboring pixels is called _______.
Interpolation
Improves spatial resolution by filling in gaps in sector-shaped images.
What is Elastography?
An emerging technique that estimates tissue stiffness/elasticity by analyzing tissue deformation
Combines ultrasound reflections to create an elastogram.
Define PACS.
Picture Archiving and Communications System; a network for digitizing and storing medical images
Provides instant access, no data degradation, and electronic transmission of images.
What does DICOM stand for?
Digital Imaging and Communications in Medicine
A set of rules for communication between imaging systems on a network.
True or False: Spatial Compounding improves temporal resolution but may reduce frame rate.
False
Spatial Compounding reduces temporal resolution.
List three advantages of PACS.
- Instant access
- No degradation of data
- Ability to electronically transmit images and reports to remote sites
What is the primary function of an Analog Scan Converter?
Making gray scale imaging possible
It utilizes a funnel-shaped vacuum tube with an electron gun and a dielectric matrix.
What are the limitations of Analog Scan Converters?
1) Image Fade 2) Image Flicker 3) Instability 4) Deterioration
These limitations affect the quality and longevity of the images produced.
What causes image fade in Analog Scan Converters?
Stored charges on the silicon wafer dissipate over time
What is the effect of image flicker in Analog Scan Converters?
Caused by switching between read and write modes, leading to less detailed images
What is the definition of bits in the context of digital imaging?
Binary digits used to represent information in the computer world
What is the significance of pixel density in digital images?
High pixel density results in many pixels per inch and more detailed images
Fill in the blank: A digital scan converter uses a process called _______ to convert images into numbers.
digitizing
What are the advantages of Digital Scan Converters?
1) Uniformity 2) Stability 3) Durability 4) Speed 5) Accuracy
These advantages make digital scan converters preferable in modern ultrasound machines.
What is the primary image storage format used in Digital Scan Converters?
A series of ones and zeros
True or False: Digital Scan Converters are affected by age or heavy use.
False
What does high spatial resolution in digital images indicate?
Higher detail and clarity in the image due to smaller pixels
What is the relationship between bits and shades of gray in digital imaging?
More bits allow for more shades of gray
What is the maximum number of shades that can be represented with 8 bits?
256
What does the term ‘spatial resolution’ refer to in imaging?
The detail and clarity of the image based on pixel density
Fill in the blank: Digital images consist of small elements called _______.
pixels
What is a key characteristic of digital numbers compared to analog numbers?
Limited choices and discrete values
What is the effect of fewer bits per pixel on image quality?
Degraded contrast resolution
Fewer shades of gray result in less detail in the image.
What is the role of an analog-to-digital (A-to-D) converter?
Converts analog signals to digital form
A string of 0s and 1s represents the analog information.
What is preprocessing in the context of ultrasound systems?
Any processing before storage in the scan converter
This occurs when the information is in digital form.
What is postprocessing in ultrasound imaging?
Any processing after storage in the digital scan converter
This is done after the image is frozen.
What happens when a display unit is analog?
Information must be translated back to analog by a D-to-A converter
This is not needed if the display is digital.
What is time gain compensation (TGC)?
A technique to adjust the gain of the received signal over time
It helps to improve image quality.
What are the main functions of coded excitation?
Provides higher S/N ratio, improved axial resolution, improved spatial resolution, improved contrast resolution, deeper penetration
These enhancements lead to better image quality.
What is the difference between write magnification and read magnification?
Write magnification acquires new data; read magnification uses old data
Write magnification cannot be used on a frozen image.
What is the outcome of using read magnification?
Unchanged spatial resolution, larger pixel size, same number of pixels as in the original ROI
It may not enhance image detail significantly.
What is the result of increased bits per pixel?
Improved contrast resolution, more shades of gray
This leads to better differentiation of structures in the image.
What does black/white inversion do in postprocessing?
Reverses the brightness values of the image
This can help in visualizing certain structures more clearly.
How does spatial compounding improve images?
Reduces artifacts and improves image quality by combining multiple images
It enhances the clarity of the final displayed image.
What is the effect of persistence/temporal compounding?
Improves image stability and reduces noise
It averages multiple frames to enhance image quality.
What is the function of edge enhancement in ultrasound imaging?
Increases the visibility of edges in the image
It helps in better delineation of structures.
What is the purpose of fill-in interpretation?
Improves visualization of structures in phased array transducers
It enhances the image quality by filling in gaps.
What does write magnification do to pixel size?
Maintains identical pixel size but has more pixels than the original ROI
This can lead to improved spatial resolution.
What is the impact of a larger pixel size in read magnification?
Unchanged spatial resolution
The image may appear less detailed.
What does improved spatial resolution indicate?
The ability to distinguish smaller structures in the image
Higher spatial resolution leads to more detailed images.
Fill in the blank: Coded Excitation provides _______.
Higher S/N ratio
This is crucial for enhancing image quality.
Fill in the blank: Larger pixel size in read magnification leads to _______.
Unchanged spatial resolution
The overall image clarity may not improve.
True or False: Postprocessing can only be performed on frozen images.
False
Postprocessing can be done after the image is captured and frozen.
What are the types of data storage mediums?
Paper Media, Magnetic Media, Chemically Mediated, Photographs, Optical Media
These categories encompass various methods and technologies used to store data.
Give examples of Paper Media.
Charts from pen, writers
Paper media include any physical documents created using writing instruments.
What are examples of Magnetic Media?
Floppy disks, Computer Discs, Magnetic Tape, Video Tape
Magnetic media utilize magnetic storage to record and retrieve data.
List examples of Chemically Mediated storage.
Photographs, Flat films, Multiformat camera film
This type of storage relies on chemical processes to capture and preserve images.
What are examples of Optical Media?
Laser discs, Compact discs (CDs)
Optical media use lasers to read and write data.
What is an advantage of Paper Media?
Does not require a device to read
Paper can be accessed without electronic devices, making it universally accessible.
What is an advantage of Magnetic Media?
Able to store large amounts of information efficiently
Magnetic media are designed to hold significant data volumes relative to their size.
What is an advantage of Chemically Mediated storage?
Can produce color images
Chemical processes in photography allow for vibrant and detailed color reproduction.
What is an advantage of Optical Media?
Can store and play dynamic (moving) images
Optical media are capable of handling video content effectively.
What is a disadvantage of Paper Media?
Bulky, hard to store
Physical documents can take up significant space and can be cumbersome to manage.
What is a disadvantage of Magnetic Media?
Can be erased by strong magnetic fields
Strong magnetic fields can disrupt the data stored on magnetic media, leading to loss.
Fill in the blank: Photographs require _______ processing.
chemical
Chemical processing is essential for developing photographs from film.
True or False: Optical Media requires a display system.
True
Optical media must be used with a compatible device to display the stored content.
What is a disadvantage of Chemically Mediated storage?
Requires chemical processing
The development of chemically mediated images necessitates specific chemical treatments.
What is a disadvantage of Optical Media?
No standardized format for image display and storage
The lack of standardization can lead to compatibility issues across different devices.
