Ch. 15 Displays and Image Processing Flashcards
bistable display
bi = two
black and white image
grayscale display
multiple levels of brightness such as white, light gray, medium gray etc.
__________________ determines the range of brilliancies within the displayed image. Bistable images, in which are only black and white appear, are high ____________________
Contrast determines the range of brilliancies within the displayed image. Bistable images, in which are only black and white, are high contrast.
________________________ determines the brilliance of the displayed image
Brightness determines the brilliance of the displayed image
_____________________________ which stores information first and later displays it; changes the format of the data (converts from spoke format to video format)
Scan Converter which stores information first and later displays it; changes the format of the data (converts from spoke format to video format)
storage of the image information in the scan converter is called ______________
storage of the image information in the scan converter is called writing
Later, image data is _________________ from the scan converter for display on the monitor
Later, image data is Read from the scan converter for display on the monitor
__________________ numbers are “real world” numbers that are found in our everyday lives.
Analog numbers are “real world” numbers that are found in our everyday lives.
Example: your weight on a scale or the length of a string
____________________ numbers are associated with computer devices.
Digital numbers are associated with computer devices
limited choices, discrete values
What was the first type of scan converter?
analog scan converter and made gray scale imaging possible
How do Analong Scan converters work?
an electron gun shot out electrons which contained the image information. These electrons strike the dielectric matrix/silicon wafer where they are stored. The stored electron charges are read to retrieve image information
What is the major benefit of an analog scan converter?
the spatial resolution is excellent
Spatial resolution is “___________________”
Spatial resolution is “image detail”
What are the 4 limitations of Analog Scan converters:
- image fade - stored charges on the silicon wafer dissipate over time
- image flicker - caused by switching between read and write modes.
- instability - picture quality depends on many factors including length of use, room temperature, and humidity
- Deteriotation - image degrades as the device ages
Digital scan converters use computer technology to convert images into numbers, a process called ________________________
Digital scan converters use computer technology to convert images into numbers, a process called digitizing
Advantages of digital scan converters:
- Uniformity: consistent gray scale quality throughout the image
- Stability: does not fade or drift
- Durability: not affected by age or heavy use
- Speed: nearly instant processing
- Accuracy: error-free
what are the two important elements of digital scan converters:
- pixel
- bit
__________________ is the smallest building block of a digital picture
Pixel is the smallest building block of a digital picture
_______________________________ is the number of picture elements per inch
Pixel Density is the number of picture elements per inch
Spatial resolution and pixel density are ______________________ (unrelated, related, directly related)
Spatial resolution and Pixel density are Directly related (which in higher pixel density = better spatial resolution)
low pixel density: ____ pixels per inch, ____ pixels, _____ detailed image, ____ spatial resolution
low pixel density:
- few pixels per inch
- larger pixels
- less detailed image
- lower spatial resolution
high pixel density: ____ pixels per inch, ____ pixels, ____ detailed image, ____ spatial resolution
high pixel density:
- many pixels per inch
- smaller pixels
- more detailed image
- higher spatial resolution
_______ is a binary digit, the smallest amount of computer memory
Bit is a binary digit, the smallest amount of computer memory
A ___________________ is a group of bits and simply a series of zeros and ones, such
A Binary number is a group of bits and simply a series of zeros and ones, such as 0101010011
A ____________ is a group of eight bits of computer memory such as 10011111
A Byte is a group of eight bits of computer memory such as 10011111
A _______________ of computer memory consists of two bytes, or 16 bits
A Word of computer memory consists of two bytes, or 16 bits
fewer bits per pixel: _______ shades of gray, _____ contrast resolution
fewer bits per pixel: fewer shades of gray, degraded contrast resolution
More bits per pixel: ___________ shades of gray, ______________ contrast resolution
more bits per pixel: more shades of gray, improved contrast resolution
Formula that determines the number of different shades of gray:
2^# of bits
5 bits, number of shades =
2 x 2 x 2 x 2 x 2 = 32 shades of gray
why do we convert analog to digital data?
digital information is far less susceptible to contamination (the info is converted back to analog before being displayed)
What is the 5 step process for converting analog info into digital info and then back again?
- the analog-digital-converter changes the electric signals created during reception from analog to digital format
- digital info is stored on the computer memory, any processing of reflected signals before storage is preprocessing
- digital info continues to be processed in the digital scan converter, any processing after storage is called postprocessing
- A digital-analog-converter changes the digital signals back to analog information to be displayed on the monitor
- the analog info is presented on the video display for interpretation
___________________________ is the manipulation of image data before storage in the scan converter
Preprocessing is the manipulation of image data before storage in the scan converter
____________________________ is the manipulation of image data after storage in the scan converter
Postprocessing is the manipulation of image data after storage in the scan converter
Time gain compensation, log compression, write magnification, persistence, spatial compounding, edge enhancement, fill-in interpolation are all apart of ________________________________
Time gain compensation, log compression, write magnification, persistence, spatial compounding, edge enhancement, fill-in interpolation are all apart of Preprocessing
Any change after freeze frame, black/white inversion, read magnification, contrast variation, 3-D rendering are all apart of ___________________________________
Any change after freeze frame, black/white inversion, read magnification, contrast variation, 3-D rendering are all apart of Postprocessing
what are two forms of magnification?
read magnification, and write magnification
____________ magnification occurs after the image data is stored in the scan converter
Read magnification occurs after the image data is stored in the scan converter
____________ magnfication is applied during data acquisition, before storage in the scan converter
Write magnification is applied during data aquisition, before storage in the scan converter
__________________________________ is a sophisticated method of improving image quality, that makes the strongest pulse possible within FDA limits, provides higher signal-to-noise ratio, improved axial, spatial and contrast resolution, deeper penetration
Coded Excitation is a sophisticzted method of improving image quality, that makes the strongest pulse possible within FDA limits, provides higher signal-to-noise ratio, improved axial, spatial and contrast resolution, deeper penetration
coded excitation occurs in the _________________________
coded excitation occurs in the pulser
higher signal-to-noise ratio, improved axial resolution, improved spatial resolution, improved contrast resolution, and deeper penetration is provided by _____________________________________
higher signal-to-noise ratio, improved axial resolution, improved spatial resolution, improved contrast resolution, and deeper penetration is provided by coded excitation
__________________________________________ is a method of using sonographic information from several different imaging angles to produce a single image. Reduces speckle and minimizes shadowing artifacts.
(is available only with phased array transducers)
Spatial Compounding is a method of using sonographic information from several different imaging angles to produce a single image.
- is available only with phased array transducers
In general, the more _____________ in the compound acquisition sequence, the better the compound image quality.
In general, the more frames in the compound aquisition sequence, the better the compound image quality
what are the limitations of spatial compounding?
reduced frame rates and reduced temporal resolution
_______________________________ is an advanced technique that reduces speckle artifact and noise in ultrasound images. the reflected signal is divided into sub-bands of limited frequencies, and an image is created from each sub-band. The images from the sub-bands are then combined, or compounded into a single image.
Frequency Compounding is an advanced technique that reduces speckle artifact and noise in ultrasound images. the reflected signal is divided into sub-bands of limited frequencies, and an image is created from each sub-band. The image from the sub-bands are then combined, or compounded into a single image.
how does frequency compounding affect the image?
reduces speckle artifact and noise
_______________ enhancement is an image processing method that makes pictures look sharper by increasing the image contrast in the area immediately around the edge (creates subtle bright and dark highlights on either side of these boundries to make them appear more defined)
Edge Enhancement is an image processing method that makes pictures look sharper by increasing the image contrast in the area immediately around the edge - by creating subtle bright and dark highlights on either side of these boundries to make them appear more defined
_______________________________, persistence, or temporal averaging, is an image processing technique that continues to display information from older images.
Temporal Compounding, persistence or temporal averaging, is an image processing technique that continues to display information from older images.
what are the consequences of temporal compounding?
reduced frame rate and temporal resolution
What does PACS stand for?
What is it?
Picture Archiving & Communications System
BMI platform configured to facilitate storing, retrieving and distributing medical images
What does DICOM stand for and what does it do?
DICOM stands for Digital Imaging and Computers in Medicine
DICOM is a set of rules, or protocols, that allows imaging systems to share information on a network.
