digital imaging and image manipulation Flashcards
-older tech
-require an additional power via adjunct box to convert photon energy to electronic digital signl
CCD
each pixel has to be sent to the ADC to be read, then transferred to voltage. what is this
[photon-to-electron conversion]
then
[electron-to-voltage conversion]
CCD
each pixel can be read in voltages directly in sensory
[ so photon to electron to voltage]
CMOS
compare/contrast CCD and CMOS
CMOS
-less power consumption (40 mW)
-low sens to xrays [CCD high]
-medium cost [CCD is high]
-voltage pixel signal [CCD is electrons]
-chip output: bit (digital) [CCD is voltage (analog)]
high sensor complex [CCD low sensor complexity]
[CCD system complexity high]
what is newer, require less power, superior?? image quality
CMOS
the number of colors (or gray shades) that a pixel is able to show
bit depth
what is the average bit depth nowadays
8 bits (2^8)=256 shades but we are around 8-16 bit depths now
increasing bit depth does what to shades of gray
increases shades of gray
___ and ____ plates have been applied in panoramic and plain skull images
CCD and PSP
why digital imaging is appealing?
-significantly less radiation
-better image(?)
-lower costs
(reduced pt chair time, no variable cost like darkroom)
-environmentally friendly- less toxic chemicals are disposed into the sewage systems
why digital imaging should be appealing
-electronic communication improves efficiency
-rapid acquisition and storage
-image portability (storage, transmission, duplication)
digital image processing/modifications-> mathematical manipulation of image data:
-compression
-imaging manipulations (qualitative)
-automated image analysis
mathematical manipulation of image data:
-compression
-imaging manipulation (qualitative)
-automated image analysis (quantitative)
-image reconstruction
what is image processing?
mathematical manipulation of image data
-uses mathematical operations called matrix transformers
-maginfy, adjust contrast, brightness, gray scale, colors, swap black and white
qualitative
-measures length(# of pixels for length, area, circumference)
-measures pixel values (bone, enamel, dentin, pulp, soft tissue densities)
quantitative
affects image file size in memory storage
-useful for storage issues (zipping) files
-actual file size is larger than stored file size
-algorithm that can shrink the file size for storage and recreate the data when retrieving the data
compression
file memory can come quite large because of
-size of grid(sensor size)
-number of images
-bit depth
affects image storage
compression
to be able to do this, the computer will change density values to predetermine numbers which then changes the image’s presentation (light or darker)
-are post-displayed mathematical algorithms that manipulate the digita signal
image manipulation
(sharpening/density/contrast/brightness)
does image manipulation increase the diagnostic accuracy?
NO
-removes low-frequency noise; increases image contrast
-exaggerate the contrast difference between adjacent pixels; to increase contrast, all pixel values are stretched; dark shades become darker and light shades become lighter
-enhances local contrast and makes edges sharper to diagnose caries, restoration fit and fractures
sharpening filter edge enhancement
applies a three dimensional effect to the image
-could be useful in presentation situations
emboss function (inactive)
-length
-angles
-bone density
-area
-circumference
-measurement calibration
automated image analysis (quanititative)
data is utilized by other software programs and produces different image presentations
image reconstruction
