2. Digital Image Processing Concepts Flashcards
1
Q
the processing of images using a computer
A
Digital Image Processing
2
Q
Steps of Digital Image Processing
A
- Converted into digital data
2. A digital image
3
Q
utilize digital image processing as their central feature of their operations
A
CR / Flat-panel DR / Digital Mammography / Fluoroscopy
4
Q
incorporate digital image processing as an essential tool to manipulate and enhance digital images
A
CT / MRI / Ultrasonography / Nuclear Medicine
5
Q
image processing expert, retired NASA engineer
A
Castleman, Kenneth R. (1994)
6
Q
uses set theory to classify images based on their form and the method used to produce them
A
Castleman, Kenneth R.
7
Q
According to him, “Images as a subset of all objects, and that image set contains subset within it, such as visible and invisible images, optical and mathematical images”
A
Castleman, Kenneth R.
8
Q
photographs, drawings, paintings
A
Visible Images
9
Q
temperature, pressure, elevation maps
A
Invisible Images
10
Q
holograms
A
Optical Images
11
Q
continuous and discrete functions
A
Mathematical Images
12
Q
important in the world of digital imaging
A
Mathematical Images
13
Q
is a continuous function that can be converted into a discrete function, both of which will generate two categories of images, namely, analog and digital images
A
classical sine wave
14
Q
is continuous wave form that changes smoothly over time
A
analog signal
15
Q
is discrete and can only have a limited number of defined values, often as simple as 1 and 0
A
digital signal
16
Q
to generate an image that is more pleasing to the observer
A
Image Enhancement
17
Q
Image Enhancement includes:
A
- Contrast enhancement
- Edge enhancement
- Spatial and Frequency filtering
- Image combining
- Noise reduction
18
Q
to improve the quality of images that have distortion or degradations
A
Image Restoration
19
Q
blurred images can be filtered to make them sharper
A
Image Restoration
20
Q
measurements and statistics, as well as segmentation, feature extraction, and classification of objects
A
Image Analysis
21
Q
are used in 3D medical imaging
A
Segmentation operations
22
Q
the goal of ______ is to simplify and/or change the representation of an image into something that is more meaningful and easier to analyze
A
segmentation
23
Q
to reduce the size of the image in order to decrease transmission time and reduce storage space
A
Image Compression
24
Q
Types of Image Compression
A
- Lossy or irreversible
2. Lossless or reversible
25
there is some loss of image details when the image is decompressed
Lossy or irreversible
26
there is no loss of any information in the image (detail is not compromised) when the image is decompressed
Lossless or reversible
27
More recent form of compression
wavelet compression (special waveforms) / Haar compression
28
Wavelet (special waveforms) compression
| Main advantage:
There is no loss in either spatial and frequency information
29
offers an approach that allows one to reduce the size of the data while at the same time improving its quality through the removal of high-frequency noise components
Wavelet compression
30
these processing operations “create images from other or non-image data”
Image Synthesis
31
these operations are used when a desired image is either physically impossible or impractical to acquire, or does not exist in a physical form at all
Image Synthesis
32
Examples of Image Synthesis
- Image reconstruction techniques
| - 3D visualization techniques which are based on computer graphics technology
33
numerical image
Matrix
34
a digital image is made up of a 2D array of numbers
Matrix
35
consists of columns (M) and rows (N) that define small square regions
Matrix
36
small square regions
Picture elements or Pixels
37
dimension of the image can be described by M, N and the size of the image is given by the relationship:
M x N x k bits (row x column)
38
Matrix size =
Field of view (FOV)
39
M=N
the image is square
40
Increasing FOV will result to:
* Increase Image processing time
* Increase Storage space
* Increase Transmission time
41
Picture element
Pixels
42
each pixel contains a number (discrete value) that represents a ______ level, which reflects the tissue characteristic being imaged
brightness
43
MRI Image matrix (in pixels)
256 x 256
44
CT Scan Image matrix (in pixels)
512 x 512
45
Ultrasound Image matrix (in pixels)
512 x 512
46
Color Doppler Image matrix (in pixels)
768 x 576
47
Digital radiography Image matrix (in pixels)
Up to 3000 x 3000
48
Digital mammography Image matrix (in pixels)
Up to 3328 x 4096
49
Computed radiography Image matrix (in pixels)
3520 x 4280
50
MRI Dynamic range (bits per pixel)
16
51
CT Scan Dynamic range (bits per pixel)
16
52
Ultrasound Dynamic range (bits per pixel)
8
53
Color Doppler Dynamic range (bits per pixel)
8
54
Digital radiography Dynamic range (bits per pixel)
Up to 16
55
Digital mammography Dynamic range (bits per pixel)
14
56
Computed radiography Dynamic range (bits per pixel)
12
57
MRI File size (per image)
131 KB
58
CT Scan File size (per image)
524 KB
59
Ultrasound File size (per image)
262 KB
60
Color Doppler File size (per image)
442 KB
61
Digital radiography File size (per image)
Up to 18 MB
62
Digital mammography File size (per image)
27 MB
63
Computed radiography File size (per image)
30 MB
64
related to atomic number and mass density of the tissues
Radiography / CT
65
represents characteristics of tissues such a proton density and relaxation times
MRI
66
DIFFERENTIAL ABSORPTION FACTORS
- High atomic number
| - Mass Density
67
how tightly the atoms of tissues are packed
Mass Density
68
Atomic number for air and soft tissue are about the same the OD changes are due to
mass density difference
69
INTERACTIONS OF X-RAYS WITH MATTER
- No interaction
- Complete absorption
- Partial absorption with scatter
70
x-ray passes completely through tissue and into the image receptor
No interaction (ex. air)
71
x-ray energy is completed absorbed by the tissue. No imaging information results
Complete absorption (ex. bone)
72
involves a partial transfer of energy to tissue, with the resulting scattered x-ray having less energy and trajectory
scattering
73
degrades image quality and causes patient and staff dose
Partial absorption with scatter
74
For digital imaging modalities, the ____ the matrix size, the ____ the pixel size, the better the spatial resolution
larger,
| smaller
75
Pixels in a digital image represent the information contained in a volume of tissue in the patient
VOXEL (3D)
76
Tissue voxel information is converted into numerical values and expressed in the pixels, and these numbers are
assigned brightness levels
77
8-bit = ____ tonal levels
256 tonal levels
78
5-bit = ____ tonal levels
32 tonal levels
79
3-bit = ____ tonal levels
8 tonal levels
80
implies that every pixel in the digital image matrix M x N is represented by k binary digits
K bits
81
The number of bits per pixel is the
bit depth
82
K bits =
2^k
83
The bit depth has an effect on the number of shades of gray, hence the _____ of the image
density resolution
84
3 STEPS IN DIGITIZING AN IMAGE
1. Scanning
2. Sampling
3. Quantization
85
the image is first divided into an array of pixels
Scanning
86
involves measuring the brightness level of each of the pixels using special devices such as PMT (Photomultiplier Tube)
Sampling
87
the signal from the PMT is an analog signal (voltage waveform) that must be a converted into a digital image for processing by a computer
Sampling
88
it determines the spatial resolution of the digitized images
Sampling
89
it determines the number of grey levels in the digitized images
Quantization
90
brightness levels obtained from sampling are assigned an integer (zero or negative or positive number) called a
gray level
91
the image is now made up of a range of gray levels
Quantization
92
total number of grays levels
Gray scale
93
Common Image Processing Operations:
Image Reformatting, Windowing, Region of Interest (ROI), Magnification, Surface and Volume Rendering, Profile, Histogram, Collage, Image Synthesis
Computed Tomography
94
Common Image Processing Operations:
Windowing, Region of Interest (ROI), Magnification, Surface and Volume Rendering, Profile, Histogram, Collage, Image Synthesis
Magnetic Resonance Imaging
95
Common Image Processing Operations:
Analytic Processing, Subtraction of images out of a sequence, Gray-scale Processing, Temporal Frame Averaging, Edge Enhancement, Pixel Shifting
Digital Subtracting Angiography/ Digital Fluoroscopy
96
Common Image Processing Operations:
Partitioned Pattern Recognition, Exposure Field Recognition, Histogram Analysis, Normalization of Raw Image Data, Gray-Scale Processing (Windowing), Spatial Filtering, Dynamic Range Control, Energy Subtraction, etc.
Computed Radiography/ Digital Radiography
97
simple and the most frequently used operation in digital diagnostic imaging
Point Processing Operations
98
the value of the one (point) input image pixel is mapped onto the corresponding output image pixel
Point Processing Operations
99
a graph of numbers of pixels in the entire image or part of the image having the same gray levels (density values) plotted as a function of the gray levels
Histogram
100
graphical display of the pixel intensity distribution for a digital image / graphical representation of the image
Histogram
101
plots the number of pixels found at each pixel value
Histogram
102
Changing the histogram of the image can alter its
brightness and contrast
103
If the histogram is modified or change, the _____ will change as well
brightness and contrast
104
Wide histogram implies _____ contrast
more
105
Narrow histogram will show _____ contrast
less
106
If the values of the histogram are concentrated in the lower end of the range of values, the image appears _____; conversely, the image appears _____ at the end of the range
dark,
| bright
107
determines the numbers assigned to the input pixel values that change them into output pixel values resulting in a change in contrast and brightness of the image
Look-up table
108
change the contrast and brightness of an image
Windowing
109
a digital image is made up of numbers, the range of numbers is the _____, controls the contrast or gray scale
Window Width (WW)
110
the center of the range is define as the _____, controls the brightness of the image
Window Level (WL)
111
_____ Window Width provides higher image contrast (short-scale)
Narrow
112
_____ Window Width will show an image with less contrast
Wide
113
one of the first step in becoming aware of and versatile with digital image processing is to understand the general nature of images
Image Formation and Representation
114
SUBSETS OF IMAGES
| CLASSIFICATION
1. Visible Images
2. Invisible Images
3. Optical Images
4. Mathematical Images
115
5 CLASSES OF DIGITAL IMAGE PROCESSING OPERATIONS
1. Image Enhancement
2. Image Restoration
3. Image Analysis
4. Image Compression
5. Image Synthesis
116
combination of lossy and lossless compression
Wavelet compression
117
How is matrix named
N x M
rows x columns
horizontal x vertical
118
High atomic number = _____ atoms
larger
119
a series of mathematical equations that are used for post processing in radiography
Look-up table
120
It is used to correct values using a mapping function
Look-up table
