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Semester 3 Advanced Ultrasound Physics > Displays and Image Processing Part 1 > Flashcards

Displays and Image Processing Part 1 Flashcards

Week 1

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1
Q

What is the meaning of the word “bi-stable”?

A

images composed of only 2 shades, black and white

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2
Q

What does gray scale mean?

A

displays multiple levels of brightness

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3
Q

What does contrast determine?

A

the range of brilliance within the displayed image.

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4
Q

Bi-stable images in which only white and black appear are what, high or low contrast?

A

High contrast

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5
Q

Brightness determines what?

A

The brilliance of the displayed image.

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6
Q

What knob controls brightness?

A

overall Gain

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7
Q

What does a scan converter do?

A

It changes the format of data. It converts the information from the spoke format ( analog) into the video (digital) format.

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8
Q

Analog numbers are what?

A

Real world numbers, 1,2,3,…..

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9
Q

Digital numbers are associated with what?

A

1’s and 0’s.

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10
Q

Analog numbers….

A
  1. real world numbers
  2. unlimited # of choices
  3. continuous values
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11
Q

Digital numbers…..

A
  1. computer world
  2. limited choices
  3. discrete values
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12
Q

Digital scan converters change what?

A

sound into electrical information then into an image on a flat screen.

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13
Q

Analog scan converter has excellent what?

A

Spatial resolution

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14
Q

Spatial resolution means what?

A

image detail

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15
Q

What type of scan converter made gray scale possible?

A

Analog scan converter

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16
Q

What are some limitations for an Analog Scan converter?

A
  1. Image fade
  2. Image flicker
  3. Instability
  4. Deterioration
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17
Q

What are some advantages of a digital scan converter?

A
  1. uniformity
  2. stability
  3. durability
  4. speed
  5. Accuracy
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18
Q

What is a pixel?

A

A pixel is the smallest element of a digital image.

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19
Q

Pixel density has to do with what?

A

pixels per square inch

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20
Q

High pixel density is achieved with what?

A

smaller pixels

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21
Q

Spatial resolution improves with higher or lower pixel density?

A

Higher pixel density.

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22
Q

Low Pixel density will have….

A
  1. fewer pixels per square inch
  2. larger pixels
  3. less detailed image
  4. lower spatial resolution
23
Q

Higher Pixel density will have….

A
  1. many pixels per square inch
  2. smaller pixels
  3. more detailed image
  4. higher spatial resolution
24
Q

What does bit mean?

A

A bit is the smallest amount of computer memory. It has a value of either 0 or 1.

25
Q

What does a byte refer to?

A

Is a group of eight bits of computer memory.

26
Q

What is a “word”.

A

a word consists of 2 bytes or 16 bits.

27
Q

What does contrast resolution refer to?

A

images with many shades of gray, this also means that the image has an increasing number of bits per pixel, more shades of gray appear on the image.

28
Q

Fewer bits per pixel will have what?

A
  1. fewer shades of gray
  2. degraded contrast resolution
29
Q

More bits per pixel will have

A
  1. more shades of gray
  2. improved contrast resolution
30
Q

A pixel has……

A
  1. an image element
  2. image detail
  3. spatial resolution
31
Q

Bits have (3 things)

A
  1. computer memory
  2. gray shades
  3. contrast resolution
32
Q

What determines a systems contrast resolution?

A

the number of grays that can be displayed

33
Q

The more grays, the better what?

A

Contrast resolution

34
Q

Digital signal is less susceptible to what?

A

contamination

35
Q

What is preposcessing?

A

A processing of the reflected signals before storage .The manipulation of image data before storage.

36
Q

What is post processing?

A

Any processing after storage in the digital scan converter. The manipulation of image data after storage.

37
Q

Processing

A
  1. TGC
  2. Log compression
  3. write magnification
  4. persistance
  5. Spatial compounding
  6. edge enhancement
  7. fill-in interpolation
38
Q

Postprocessing

A
  1. any change after freeze frame
  2. black/white inversion
  3. Read magnification
  4. contrast variation
  5. 3-D rendering
39
Q

What 2 types of magnification exist?

A
  1. read magnification
  2. Write magnification
40
Q

What is READ Magnification?

A

occurs after the image data is stored in the scan converter.

41
Q

What is read magnification characterized by?

A
  1. The number of scan lines in the magnified image.
42
Q

Is read magnification pre or post processing?

A

postprocessing

43
Q

What is Write magnification?

A

is applied during data acquisition, before storage in the scan converter.

44
Q

Read magnification has what 6 things?

A
  1. uses old data
  2. postprocessing
  3. larger pixel size
  4. same # of pixels as in the original ROI
  5. unchanged spatial resolution
  6. unchanged temporal resolution
45
Q

Write magnification……..

A
  1. acquires new data
  2. preprocessing
  3. identical pixel size
  4. more pixels than in the original ROI
  5. improved spatial resolution
  6. may improve temporal resolution
46
Q

What does PACS stand for?

A

Picture
Archiving and
Communications
System

47
Q

True or False, digital scan converters do not use computer technology to process electronic data into images?

A

False

48
Q

What happens to a digital image when the pixel density increases?

A

Spatial detail improves

49
Q

True or False, the greater the number of bits assigned to each pixel of a digital image the greater the number of shades and gray the image has?

A

True

50
Q

What happens to an image when the number of bits allocated to each pixel increases?

A

more shades of gray

51
Q

What is the maximum number of shades of gray that are represented with 4 bits?

A

16

52
Q

Spatial resolution improves with what?

A

high pixel density

52
Q

True or false, for digital image info to be displayed on a conventional TV, the data must be processed by a digital to analog converter?

A

True

53
Q

Spatial resolution creates an image with what?

A

greater detail

Semester 3 Advanced Ultrasound Physics (4 decks)

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