Digital Images Flashcards
What is the singular of ‘data’?
Datum
What can image analysis be used for?
To calculate morphological parameters on a computer
List the different types of radiation on the electorate-magnetic spectrum from the largest wavelength to the smallest.
Radio Microwave Infrared Visible Ultraviolet X-ray Gamma ray
What is the wavelength of radio waves?
10^3
What is the wavelength of microwaves?
10^-2
What is the wavelength of infrared?
10^-5
What is the wavelength of visible light?
0.5x10^-6
What can image processing and analysis be used for in a biological context?
CT-scanner CT slice MRI radiography Counting objects (e.g. bacteria)
How many bits in a byte?
8 bits are in a byte
How many bytes are in a pixel?
A pixel = 1 byte
What is a pixel?
a sample of light based in that particular position
How many different combinations are there of 0 and 1 in a single byte?
256
An image is a sequence of numbers ranging between 0 and _____
255 (not 256 because we start at 0)
How many bytes does a greyscale image of size 800x600 occupy on the computer?
800x600= 480000 Bytes (480kB)
Because 1 pixel= 1 byte so an image of size MxN pixels occupies M x N Bytes
Some images use more than 8 bits for storing grey levels. With 16 bits, how many different values of grey can a pixel assume up to?
2^16 = 65536 different values of grey
How many Bytes does an RGB image of size 800x600 occupy on the computer?
800 x 600 x 3 = 1,440,000 Bytes (1.44 MB)
To get MB divide by 1 million
What three colours are used in colour images?
Red, Green, Blue
Image formation means?
Object in, image out (on computer)
Image processing means?
Image in, image out
Image analysis means?
Image in, features out (for example, area and perimeter)
Computer graphics means?
Numbers in, image out
Computer vision means?
Image in, interpretation out
Visualisation means?
Image in, representation out
What does the operation ‘image processing’ do?
1) Enhancement and restoration
2) segmentation (thresholding and edge detection)