Chapter 15-17, 22 Flashcards
Is old fashioned or modern b-mode bistable?
Old-fashioned is bistable. Modern is greyscale.
Is bistable imaging high or low contrast? How does this relate to Dynamic range?
Contrast is the range of brilliance in an image. Bistable is high contrast and decreased DR.
What is brightness? Does this change with contrast?
Brightness is light or dark. It does not change dynamic range or contrast at all.
What are advantages to digital scan converters?
Uniformity, stability, durability, and accuracy
What is a pixel? What is pixel density?
Each picture element is one pixel and each is a shade of grey. Pixel density is the numberof pixels per inch.
How is a high pixel density related to spacial resolution?
More pixels per inch = high spatial resolution
What is a bit?
the smallest amount of computer memory. Either 0 or 1
What is a byte?
A group of 8 bits. Example 01100101
What is a word?
two bytes or 16 bits.
A higher number of bits per pixel creates more shades of grey, How does this affect contrast resolution.
It imporoves contrast resolution.
How are bits mathematically related to shades of grey?
They are exponential. 3 bits = 8 shades because 2 to the 3rd power = 8
Computer memory, grey shades, and contrast resolution have to do with..?
bits
Image element, image detail, and spatial resolution have to do with..?
pixels
TGC, write magnification, and log compression are related to what kind of processing
Pre-Processing
black and white inversion, read magnification, and contrast variation are related to which type of processing
Post-Processing
What kind of magnification expands the chosen ROI and has the same number of pixels as the original image?
Read magnification- zoom after the image is stored. It cannot be changed.
What kind of magnification re-assigns pixels in the ROI? Does this create a better or worse image?
Write magnification. It is a better image because more pixels are assigned in the area, they are not expanded, since that is the only area being processed.
Which type of magnification improves spatial and temporal resolution?
Write magnification
A method of reporting the extent to which a signal can vary and still be accurately measured is called..?
Dynamic Range
explain dynamic range
Comparison or ratio between the largest and smallest signals or the number of available choices
Signals that are too weak to be accurately displayed are called..?
below the threshold
Signals that are too weak to be accurately displayed are called..?
saturating the system
Does dynamic range increase or decrease as it is processed? What does this mean for components that are processed earlier?
It decreases. Components early on have a wider dynamic range.
How do yoy calculate a component’s dynamic range?
Divide the bigger voltage by the smaller. For every zero, count a 20dB change.
