Displays
Black and white - high contrast
Bistable
Converts radiofrequency pattern into interlaced or video format
Scan Converter
Smallest element of digital image
Pixel
determine shades of gray by multiplying ____
2 raised to the number of bits
# of bits
Exponent
Number of Shades
0 2o 1
1 21 2
2 22 4
3 23 8
Manipulation of image data before storage
Preprocessing
Multiple levels of brightness, low contrast
Grayscale
Limited choices, discrete values
Digital Numbers
Always whole numbers and continuous values
Number of pixels per square inch
Pixel Density
The only digits included in binary numbers
0 and 1
Can preprocessing be undone?
Controlled?
No.
Yes.
Determines range of brilliances within the displayed image
Contrast
Image detail
Spatial Resolution
Relationship between pixel density and spatial resolution
Direct
^ pixels per square inch = ^ pixels = ^ detailed image = ^ spatial resolution
Binary is based on the base of ___ raised to exponents
2
Manipulation of data after storage in the scan converter
Postprocessing
Determines brilliance of displayed image
Brightness
Converting images to numbers
Digitizing
Smallest amount of computer memory
Group of ___ = 1 byte
Group of ___ = 2 bytes = 1 ____
Bit
8 bits
16 bits, word
29 as a binary number
11101
Can postprocessing be undone?
Controlled?
Yes.
Yes.
Order of image creation
Transducer > Receiver > Scan Converter >Display
Advantages of Digital Scan Converters
Uniform, stable, durable, speed, accuracy
Relationship between bits per pixel and contrast resolution
Direct
^ bits per pixel = ^ shades of grey = ^ contrast resolution
1001001 in decimal number
73
Examples of Preprocessing
Examples of postprocessing
Time Gain Compensation, Log Compression, Write Mag, Persistence, Spatial Compounding, Edge Enhancement, Fill-in Interpolation
After freezing, black/white inversion, Read Mag, Contrast Variation, 3-D Rendering