LECTURE 13 Flashcards
SCAN CONVERTER IS ALSO KNOWN AS:
MEMORY
FUNCTION OF SCAN CONVERTER:
STORES INFO FROM RECEIVER.
TWO METHODS OF STORING DATA:
ANALOG AND DIGITAL.
ADVANTAGE/DISADVANTAGE OF ANALOG SCAN CONVERTER:
EXCELLENT RESOLUTION.
UNSTABLE IMAGE.
WHAT DOES A DIGITAL SCAN CONVERTER DO?
- TRANSLATES ANALOG INFORMATION TO DIGITAL AND STORES DATA IN DIGITAL FORM.
- SIGNALS STORED AS NUMBERS IN RAM.
(NUMBERS ARE BINARY)
ADVANTAGE OF A DIGITAL SCAN CONVERTER:
DIGITAL STORAGE IS VERY STABLE.
WHAT IS A BIT?
BINARY NUMBER.
T/F: A BIT CAN ONLY BE ON OR OFF.
TRUE
0=OFF
1=ON
HOW MANY BITS MAKE UP A BYTE?
8
WHAT IS A PIXEL?
A SINGLE POINT IN A GRAPHIC IMAGE.
INFORMATION IS STORED AS A BIT WITHIN A PIXEL
THE MORE PIXELS THE BETTER THE:
SPATIAL RESOLUTION.
WHY IS THERE BETTER SPATIAL RESOLUTION WITH MORE PIXELS?
PIXEL DENSITY INCREASES.
SPATIAL RESOLUTION INCREASES.
HOW MANY SHADES OF GRAY WILL:
A TWO BIT SYSTEM DISPLAY?
A FIVE BIT SYSTEM DISPLAY?
- 4
- 32
THE GREATER THE NUMBER OF BITS:
-THE BETTER THE CONTRAST RESOLUTION.
PIXEL’S LOCATION RELATES TO:
ECHO ARRIVAL TIME AND BEAM ORIENTATION.
PREPROCESSING OCCURS:
BEFORE INFORMATION HAS BEEN STORED IN MEMORY.
T/F: POSTPROCESSING OCCURS IMMEDIATELY AFTER THE INFORMATION IS RECEIVED FROM TRANSDUCER.
FALSE.
PREPROCESSING OR POSTPROCESSING?
RES (WRITE ZOOM, HD ZOOM)
PRE
PREPROCESSING OR POSTPROCESSING? DISTANCE MEASUREMENT (CALIPER PLACEMENT)
POST
PREPROCESSING OR POSTPROCESSING? DYNAMIC RANGE (LOG COMPRESSION)
PRE
PREPROCESSING OR POSTPROCESSING? READ MAGNIFICATION (ZOOM)
POST
PREPROCESSING OR POSTPROCESSING?
B/W INVERSION
POST
PREPROCESSING OR POSTPROCESSING?
TGC
PRE
A TYPE OF FRAME AVERAGING USED TO MAKE THE IMAGE APPEAR SMOOTHER.
PERSISTANCE
HIGHER PERSISTANCE RESULTS IN:
DECREASED TEMPORAL RESOLUTION (FRAME RATE).
HIGHER PERSISTANCE IS USED FOR:
SLOW MOVING STRUCTURES.
EDGE ENHANCEMENT IS GOOD FOR:
DIFFERENTIATING CYSTS FROM MASSES.
T/F: TOO MUCH SMOOTHING WILL RESULT IN A LOSS OF TEMPORAL DETAIL.
FALSE - SPATIAL DETAIL.
- A TECHNIQUE USED FOR FILLING IN MISSING PIXELS. (SPACIAL COMPOUNDING)
- ADDS SIGNAL BRIGHTNESS BASED ON AVERAGE BRIGHTNESS OF SURROUNDING PIXELS.
FILL-IN INTERPOLATION
INCREASING THE NUMBER OF SHADES OF GRAY:
ADD MORE BITS TO SYSTEM.
MORE BITS=MORE SHADES OF GRAY
DETERMINING HOW MANY SHADES OF GRAY SCAN CONVERTER CAN DISPLAY:
NUMBER 2 RAISED TO THE POWER OF THE NUMBER OF BITS.
PREPROCESSING:
- ALLOWS CHANGE, ALTERATION OR MANIPULATION OF ECHO SIGNALS BEFORE STORED IN CPU MEMORY.
- NOT OPERABLE AFTER IMAGE IS FROZEN.
- WAY OF ENLARGING AREA OF INTEREST ONLY.
- ALL SCAN LINES AND MORE PIXELS CONTAINED.
- BETTER SPACIAL RESOLUTION.
WRITE ZOOM (RES)
POSTPROCESSING:
- ALLOWS SONOGRAPHER TO CHANGE, MANIPULATE, OR ALTER ECHO SIGNALS AFTER BEING STORED IN CPU MEMORY.
- ONLY AFTER FRAME IS FROZEN.
A TYPE OF FILTERING TO INCREASE THE APPEARANCE OF SMALL HIGH CONTRAST STRUCTURES.
EDGE ENHANCEMENT.
- FILTERING TECHNIQUE USED TO REDUCE NOISE.
- TYPE OF PIXEL AVERAGING.
- MAKES IMAGE APPEAR SMOOTHER (SOFTER).
- TOO MUCH CAN RESULT IN A LOSS OF SPATIAL DETAIL.
SMOOTHING.
