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ACOUSTICAL PHYSICS > Ch 15: Displays and Image Processing > Flashcards

Ch 15: Displays and Image Processing Flashcards

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1
Q

Bistable images are composed of how many shades?

A

two: black and white

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2
Q

What two user controls can alter characteristics of displayed images?

A

contrast and brightness

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3
Q

This determines the range of brilliancies withing the displayed image.

A

contrast

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4
Q

T/F? Bistable images are high contrast.

A

true

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5
Q

This determines the brilliance of the displayed images

A

brightness

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6
Q

This translates the information from the spoke format into the video format.

A

scan converter

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7
Q

These ‘real world’ numbers have a continuous range of values.

A

analog

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8
Q

These ‘computer’ numbershave only discrete values.

A

digital

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9
Q

This is a funnel-shaped vacuum tube with an electron gun located within its smaller end.

A

analog scan converter

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10
Q

These charged particles contain image information.

A

electrons

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11
Q

This is in the larger end of the electron gun where the electrons are stored.

A

dielectric matrix or silicon wafer

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12
Q

This is when stored charges on the silicon wafer dissipate over time.

A

image fade

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13
Q

This is caused by switching between read and wrtie modes.

A

image flicker

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14
Q

This is when picture quality depends on many factors including length of use, room temperaure, and humidity.

A

instability

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15
Q

This is when an image degrades as the device ages.

A

deterioration

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16
Q

Why are analog scanners now obsolete?

A
  1. image fade
  2. image flicker
  3. instability
  4. deterioration
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17
Q

This is the process of converting images into numbers.

A

digitizing

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18
Q

This is the consistent gray scale quality throughout an image.

A

uniformity

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19
Q

This is how an image does not fade or drift.

A

stability

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20
Q

This is when an image is not affected by age or heavy use.

A

durabiilty

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21
Q

What are the advantages of digital scan converters?

A
  1. uniformity
  2. stability
  3. durability
  4. speed
  5. accuracy
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22
Q

Two important elements of digital scan converters are…

A
  1. pixel

2. bit

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23
Q

Pixel comes from the words…

A

picture element.

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24
Q

This is the smallest building block of a digital picture.

A

pixel

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25
Q

The entire pixel is how many shades of gray?

A

one

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26
Q

This is the number of picture elements per inch.

A

pixel density

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27
Q

Higher pixel density is achieved with __ pixels per inch and __ pixels.

A

many, smaller

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28
Q

The word ‘bit’ is derived from the terms…

A

binary digit.

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29
Q

A bit is __, having a value of 1 or 0.

A

bistable

30
Q

This is a group of eight bits of computer memory.

A

byte

31
Q

This is consists of two bytes or 16 bits.

A

word

32
Q

More bits per pixel give you __ shades of gray and __ contrast resolution.

A

more, improved

33
Q

To determine the number of gray shades represented by a cluster of bits…

A

2^# of bits

34
Q

How many shades of gray are displayed with 5 bits of memory?

A

2 x 2 x 2 x 2 x 2 = 32

35
Q

This converts the electrical signals from analog to digital form.

A

analog-to-digital (A-to-D) converter

36
Q

Any processing of the reflected signals before storage is called…

A

preprocessing.

37
Q

Any processing after storage in the digital scan converter is called…

A

postprocessing

38
Q

This translates the digital signals back into analog form.

A

digital-to-analog (D-to-A) converter

39
Q

T/F? Preprocessing alters the image data forever and cannot be reversed or undone.

A

true

40
Q

Any alterations to a frozen image must be…

A

postprocessing.

41
Q

This can improve visualization of detail by enlarging a portion of the screen.

A

Magnification (zoom)

42
Q

This kind of magnification happens after the image data is stored in the scan converter.

A

Read magnification

43
Q

T/F? In read magnification, the ROI is rescanned.

A

FALSE, not rescanned

44
Q

T/F? In read magnification, the number of pixels or scan lines in the magnified image is the same as in the original image.

A

True

45
Q

Are the pixels smaller or larger in read magnification?

A

Larger

46
Q

This kind of magnification is applied during data acquisition, before storage in the scan converter.

A

Write magnification

47
Q

T/F? In write magnification, the ROI is rescanned.

A

True

48
Q

T/F? The number of pixels and scan lines in ROI write magnification stay the same.

A

FALSE, they are greater than the original image.

49
Q

T/F? The increased number of pixels in ROI write magnification improves spatial resolution.

A

True

50
Q

T/F? With write magnification, spatial resolution may be improved if the bottom of the ROI is shallower than the original images depth of view.

A

FALSE, temporal resolution

51
Q

This is a sophisticated method of improving image quality within the context of bioeffects.

A

Coded excitation

52
Q

Where does coded excitation occur?

A

In the pulser

53
Q

T/F? Coded excitation creates very short sound pulses containing a wide range of frequencies.

A

FALSE, very long sound pulses

54
Q

This is a method of using info from several different angles to produce a single image.

A

Spatial compounding

55
Q

The Limitations of spatial compounding are…

A
  1. Reduced frame rate

2. Reduced temporal resolution

56
Q

T/F? Spatial compounding is available only with phased array transducers.

A

True

57
Q

This is an advanced technique that reduces speckle artifact and noise in ultrasound images.

A

Frequency compounding

58
Q

With frequency compounding, the reflected signal is divided into sub bands of __ , and an image is created from each __

A

Limited frequencies, sub band

59
Q

This image processing method makes pictures look sharper.

A

Edge enhancement

60
Q

This image processing technique continues to display info from older images.

A

Temporal compounding (persistence, temporal averaging)

61
Q

The primary limitation of persistence is a…

A

Reduction in the displayed frame rate.

62
Q

T/F? Persistence is most effective with slowly moving structures.

A

True

63
Q

How do persistence and spatial compounding differ?

A

Persistence uses images all from the same view, and spatial compounding images are all from different angles.

64
Q

This is a method of constructing new simulated data points to fill in the gaps of sector shaped images.

A

fill-in interpolation

65
Q

This imaging technique is related to the mechanical properties of tissue, particularly how the tissue deforms following the application of a force.

A

elastography

66
Q

PACS stands for…

A

Picture Archiving Communications System

67
Q

What are the three main advantages of a PACS?

A
  1. instant access to archived studies
  2. no degradation of data
  3. the ability to email images and reports to remote sites
68
Q

What is the primary digital storage device used in PACS?

A

the computer hard drive

69
Q

DICOM stands for…

A

Digital Imaging Computers in Medicine

70
Q

This is a set of rules or protocols that allows imaging systems to share information on a network.

A

DICOM

ACOUSTICAL PHYSICS (23 decks)

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