Sensors and Digital Imaging- Lecture 6 Flashcards
List the reasons to change from traditional to digital imaging: (7)
- significantly less radiation
- better image
- lower cost (more net income)
- environmentally friendly (less toxic chemicals are disposed into the sewage systems)
- electronic communication improves efficiency
- rapid acquisition
- image portability (storage, transmission, duplication)
others- eliminates the need for film, processing, dark room setup, chemicals and therefore increases workflow and efficiency
Image created when photons break up the silver halide crystals and the bromine and fluorine crystals float around and create an image based on how their energy was changed:
Film image
Chemical changes in processing occurs with what type of image?
film image
Image created when the shadow created by the object being captured is transferred to electrical charges that are assigned a numerical value by the computer which is then converted to a certain color of grey and an image is created:
digital image
The general steps in digital image formation include: (4)
- x-ray shadow
- shadow image detected by digital sensor
- numerical pixel values sent to the computer
- digital image displayed on computer screen
In the first step of digital image formation (x-ray shadow), the shadow is created by:
an object
In the second step of digital image formation (shadow image detected by digital sensor), the pixels are ___. Each pixel has a ____ charge.
electrified; pre-exposure electrical charge
In the second step of digital image formation (shadow image detected by digital sensor), x-ray photons that make it to the sensor change there ____ in those pixels
electric charge
In the second step of digital image formation (shadow image detected by digital sensor), the thicker/dense the body part:
the less x-photons can affect the electrical charge
In the second step of digital image formation (shadow image detected by digital sensor), what is the net effect?
there is a shadow of electric charges on the sensor relative to the thickness/density of the body part
In the third step of digital image formation (numerical pixel values sent to the computer), electric charge value of each pixel is converted to a:
numerical value (digitized)
In the third step of digital image formation (numerical pixel values sent to the computer), ____ is sent to the computer for further processing.
pixel value
In the fourth step of digital image formation (digital image displayed on the computer screen), the computer assigns a ____ to each number
grey value
In the fourth step of digital image formation (digital image displayed on the computer screen), the gray values are displayed:
in a visual
Pixel is derived from the words:
PEL (picture element)
The smallest portion of a sensor, image, or display that is capable of being recorded and then print or displayed:
Pixel (px)
Each pixel is assigned a ___ and translated to a ___.
numerical value; specific shade of gray
Image quality:
spatial resolution
The smaller the pixel, the ____ the image will be
sharper (/better resolution)
The smaller the pixel, the ___ the processing time
longer
digital has a ___ pixel size compared to film
larger
The ability of the display/computer to distinguish between differences in color intensity:
contrast resolution
The number of gray shades that a pixel is able to display:
Bit depth
What effect does bit depth have on contrast resolution?
An increase in bit depth –> decreases contrast resolution
2 ^(BIT) =
shades of gray visible
If the bit is 2, then how many shades of gray are visible?
2^3= 8 shades
List the different ways of digital image acquisition: (3)
- indirect/hybrid
- digital indirect (semi direct)/computed radiography
- digital direct/ digital radiography
Digital indirect image acquisition may be considered:
semi direct or computed radiography
Digital direct image acquisition may be considered:
digital radiography
What form of digital acquisition is being described?
- slide scanner, flawed scanner, film, digital camera
Indirect/hybrid
What form of digital acquisition is being described?
- phosphor storage plate (PSP)
Digital indirect (semi direct) (computed radiography)
What form of digital acquisition is being described?
- charge-coupled device (CCD)
- complement metal oxide semiconductor (CMOS)
Digital direct (digital radiography)
PSP:
phosphor storage plate
CCD:
charge-coupled device
CMOS
Complementary Metal Oxide Semi-Conductor
Label the following components of a CCD sensor:
Top arrow: cable side housing + cable
magenta: electronic substrate
purple: CMOS imaging chip
clear: fiber optic face plate (FOP)
green: CSI scintillator
black: front side housing
List the steps involved in the functioning of CCD sensors:
- Celsium iodide scintillator converts x-rays into visible light
- Photosensitive pixels convert scintillators light into electrical signals. On-chip circuitry turns electrical signals into digital output
- digital data is sent to computer
In the first step in the functioning of CCD sensors, Celsium Iodide scintillator converts _____ Into ____.
x-rays into visible light
In the second step in the functioning of CCD sensors, ____ convert scintillators light into ____
photosensitive pixels; electrical signals
In the second step in the functioning of CCD sensors, the on-chip circuitry turns electrical signals into:
digital output
In the third step in the functioning of CCD sensors, digital data is sent to:
a computer
CCDs have ____ radiation than CMOS
less radiation
In CCD/ CMOS digitization, x-ray photons cause ____ of ___ and the ejected electrons are trapped in a pixel in similar fashion to the charge of a battery
ionization of silicone
In CCD/ CMOS digitization, x-ray photons cause ionization of silicone and the ejected electrons are trapped in a pixel in similar fashion to the charge of a battery.
The computer then calculates the ___ in each pixel and converts it to a value which is then converted to a _____.
charge; scale of gray
Solid state sensors include:
CCD & CMOS
Solid state sensors (CCD/CMOS) use ____ material
scintillating
“each pixel is like a tiny battery with its charge equal to the number of electrons trapped inside. The computer records the charge in each pixel and converts it to a gray value”
This is a simplified explanation for:
CCD/CMOS digitiziation
Inherent problems associated with CCD sensors include:
- Older technology takes longer because each row of pixels is read sequentially
- CCD is more expensive and consumes more power and requires adjunct box to convert from analog to digital
Describe the CMOS structure and how its different from CCD:
very similar to CCD EXCEPT the photon to electron conversion, and electron to voltage conversion occur within each individual pixel so its much quicker and DOES NOT require an adjunct box
If we say “much quicker and does NOT require an adjunct box” we are describing:
CMOS
What are some CMOS pros (over CCD):
- newer technology
- faster
- requires less power
- superior image quality
What is faster, CMOS or CCD?
CMOS
What has superior image quality? CMOS or CCD?
CMOS
Which requires less power? CMOS or CCD?
CMOS
PSP plates are coated with ___ (Europium doped barium fluorobromide) which produces a ___ when these phosphors are ____.
crystalline halide emulsion; latent image; ionized
What are PSP plates coated with?
crystalline halide emulsion
Describe the steps in PSP Functioning:
- _____
- PSP plates are coated with crystalline halide emulsion which:
- Scanned with:
- Emits ____ from ___ in in ionized fluorophores
- Intensified by a:
- Light intensity is converted to:
- Expose plate to strong light to erase images by:
- ____
- x-rays
- produces a latent image she these phosphors are ionized
- red laser beam
- fluorescent light; excitation of valance electrons
- photomultiplier tube
- digital data
- neutralizing charge in ionized fluorophores
- reuse
What are some advantages to PSP plates? (4)
- reusable
- once digitized can be viewed and sent anywhere
- storage takes up less space than film
- processing is easier than film (but has physical similarities to film)
Although processing of PSP plates is is easier than film, there are ____ to film.
physical similarities
Which is describing PSP plates? Which is describing CCD sensors?
- Is a direct digital system, where the image is taken then shows up directly on the computer
- Requires a plate transfer box due to light sensitivity
- Requires a scanner before they are able to be viewed on the computer
- CCD
- PSP
- PSP
What are the two main parts of sensors: (CCD/CMOS)
- external size
- internal active area
The portion of the sensor (CCD/CMOS) that is producing the image:
internal active area
Post-display mathematical algorithms that manipulate the digital signal:
imaging manipulations (enhancements)
Imaging manipulations include: (7)
- edge enhancement (sharpening)
- noise reduction (softening)
- optimizing of density/contrast
- inversion of gray scale
- magnification
- emboss function
- pseudocolor enhancement
Edge enhancement may also be considered:
sharpening
Noise reduction may also be considered:
softening
____ and ___ adjustments are don’t together to find the best combination to highlight the clarity of the structures
brightness & contrast
What do these buttons mean:
Blue: Undo
Purple: Redo
What do these buttons mean:
Reset
What do these buttons mean:
Pink: Rotate 90 degrees
Purple: Show/Hide ~brightness/contrast
Green: Show/Hide ~ histogram
What do these buttons mean:
Purple: Noise reduction
Pink: Edge enhancement “sharpened”
Blue: Magnifier
What do these buttons mean:
Orange: Zoom
Blue: Fit to Frame
Purple: Fit Image to Screen Resolution (Best)
What do these buttons mean:
