image processor Flashcards
image processor includes?
- preprocessor
- scan converter
- image memory
- postprocessor
- digital-to-analog converter
scan line info is?
- built into frames of information
- pre-processed
scan conversion?
- done by scan conveter
- building a frame
- properly located each echo on image frame
- real time
- echo info (scan lines) to image form (frames)
scan convertion how many scan lines in a frame?
96-256 scan lines in a frame
Each frame is made up of a ‘matrix’ of tiny blocks called?
pixels
typically pixels in a matrix?
- 1024 x 768
- 512 x 384
3D =
voxels
pre-processing?
- before freeze
- done while echo data is being stored in memory
- the frame is still being built during this time
post-processing?
- freeze
- done on image retrieved from image memory
prepocession characteristics? (6)
- before the data is stored in memory
- persistence
- panoramic
- 3D
- spatial compounding
- write magnification
post processing characteristics? (6)
- after data is stored in image memory
- b colour
- freeze frame
- black/white image invention
- read magnification
- contrast variation
what is edge enhancement?
- pre-processing
- sharpens boundaries to make them more detectable and make measurements more precise
pixel interpolation aka?
- fill-in interpolation
- filling in missed pixels
what is spacial compounding?
- hit the same object from different angles and average the images
- trying to hit structures at 90 degrees
persistance?
- aks frame averaging
- averaging of sequential frames
- reduces noise
persistance affects?
- better contrast resolution
- operator controlled
- decreased FR
what is 4D imaging?
= 3D + time
B- colour aka?
- tint/ colour scale
- chroma map
the human eye can see how many shades of grey and colour?
100 shades of grey
256 shades of colour
what is read magnification?
- pulls out specific pixels from the frame from memory and displays them using the entire display
drawbacks of image processor?
- enlargement of pixels
what is write magnificaiton?
- smaller field of view is written using pixels for entire frame
- better resolution
image memory?
- aks digital memory
what is freeze frame?
displays lastest image stored in memory
what is cineloop?
displays last 100-130 images
what does each pixel contain?
brightness (intesity/amplitude) at a particular anatomical position
one matrix can show how many shades of grey?
2 (on and off)
a 1-bit pixel is called?
bistable
a 1-bit pixel is called?
bistable
3 bit memory = how many shades of grey?
8
what is a binary number system?
alternative to decimal (arabic) number system
what is contrast resolution?
being able to seperate 2 different echoes as 2 different shades of grey
1024 bytes =?
1 kilobyte
display requires what kind of signals?
analog
digital-to-analog converter?
Digital memory (#’s) - voltages for display
frame rate?
of images stored in memory per second
refresh rate?
of images displayed per second
temporal resolution?
- ability of a display to distinguish closely spaced events in time and present rapidly moving structures correctly
- Higher frame rate improves temp res
temporal reolution- what does each from contain?
LPF- lines per frame
n- number of foci
each focus and line require?
a pulse
to increase the number of foci?
the PRF must increase
to increase the number of lines per frame?
the PRF must increase
to increase FR?
PRF must increase
temporal resolution depends on?
- FR
