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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

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
What does a byte refer to?
Is a group of eight bits of computer memory.
26
What is a "word".
a word consists of 2 bytes or 16 bits.
27
What does contrast resolution refer to?
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
Fewer bits per pixel will have what?
1. fewer shades of gray 2. degraded contrast resolution
29
More bits per pixel will have
1. more shades of gray 2. improved contrast resolution
30
A pixel has……
1. an image element 2. image detail 3. spatial resolution
31
Bits have (3 things)
1. computer memory 2. gray shades 3. contrast resolution
32
What determines a systems contrast resolution?
the number of grays that can be displayed
33
The more grays, the better what?
Contrast resolution
34
Digital signal is less susceptible to what?
contamination
35
What is preposcessing?
A processing of the reflected signals before storage .The manipulation of image data before storage.
36
What is post processing?
Any processing after storage in the digital scan converter. The manipulation of image data after storage.
37
Processing
1. TGC 2. Log compression 3. write magnification 4. persistance 5. Spatial compounding 6. edge enhancement 7. fill-in interpolation
38
Postprocessing
1. any change after freeze frame 2. black/white inversion 3. Read magnification 4. contrast variation 5. 3-D rendering
39
What 2 types of magnification exist?
1. read magnification 2. Write magnification
40
What is READ Magnification?
occurs after the image data is stored in the scan converter.
41
What is read magnification characterized by?
1. The number of scan lines in the magnified image.
42
Is read magnification pre or post processing?
postprocessing
43
What is Write magnification?
is applied during data acquisition, before storage in the scan converter.
44
Read magnification has what 6 things?
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
Write magnification........
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
What does PACS stand for?
Picture Archiving and Communications System
47
True or False, digital scan converters do not use computer technology to process electronic data into images?
False
48
What happens to a digital image when the pixel density increases?
Spatial detail improves
49
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?
True
50
What happens to an image when the number of bits allocated to each pixel increases?
more shades of gray
51
What is the maximum number of shades of gray that are represented with 4 bits?
16
52
Spatial resolution improves with what?
high pixel density
52
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?
True
53
Spatial resolution creates an image with what?
greater detail

Semester 3 Advanced Ultrasound Physics (6 decks)

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