15 Image Processing + Dynamic Range Flashcards
What is read magnification?
Does not rescan, only reads image in memory
Reads old data
Postprocessing
Same line density
LARGER pixels
Unchanged spatial and temporal resolution
What is write magnification?
Rescans & acquires new data, discards old data Writes new data Preprocessing Increased line density MORE pixels Improved spatial resolution Temporal resolution can change
What is fill-in interpolation?
Filling in gaps between lines
Preprocessing
How does interpolation improve image detail (spatial resolution)?
Filling in missing data, especially for deeper parts of a sector-shaped image
What is speckle?
Artifact that is grainy or granular appearance in tissues that are really homgenous
How is speckle created?
Interference effects of scattered sound, both constructive & destructive, from many tiny tissue reflectors
What is spatial compounding?
Scan lines are steered by the transducer in different directions or views and frames are averaged, improving signal-to-noise ratio
What transducers have spatial compounding?
Phased array
What is temporal compounding or persistence?
History of past frames that are overlaid or added on top of the current frame and averages previous frames producing a consolidation of past frames in the resulting image
What is frequency compounding?
Creating an image by averaging frames obtained from different frequency sub-bands
What type of compounding does not change temporal resolution?
Frequency compounding
What is dynamic aperture?
Form of electronic receive focusing by varying the number of elements used to receive the reflected signal
What is edge enhancement?
Increases the contrast at a boundary to make an image appear sharper
What is coded excitation?
Long sound pulses that contain a complex pattern of frequencies and cycles - code
Occurs in the pulser
What does coded excitation improve?
Penetration, axial resolution, spatial resolution and contrast resolution
