© 2002 by yu hen hu 1 ece533 digital image processing image acquisition
TRANSCRIPT
© 2002 by Yu Hen Hu1ECE533 Digital Image Processing
Image Acquisition
© 2002 by Yu Hen Hu2ECE533 Digital Image Processing
Electromagnetic Spectrum
The wavelength required to “see” an object must be the same size or smaller than the object
© 2002 by Yu Hen Hu3ECE533 Digital Image Processing
Image Sensors
© 2002 by Yu Hen Hu4ECE533 Digital Image Processing
Sensor Strips
© 2002 by Yu Hen Hu5ECE533 Digital Image Processing
Chapter 2: Digital Image FundamentalsChapter 2: Digital Image Fundamentals
© 2002 by Yu Hen Hu6ECE533 Digital Image Processing
Chapter 2: Digital Image FundamentalsChapter 2: Digital Image Fundamentals
© 2002 by Yu Hen Hu7ECE533 Digital Image Processing
Chapter 2: Digital Image FundamentalsChapter 2: Digital Image Fundamentals
© 2002 by Yu Hen Hu8ECE533 Digital Image Processing
Digital Image Representation
An image is a function defined on a 2D coordinate f(x,y).
The value of f(x,y) is the intensity.
3 such functions can be defined for a color image, each represents one color component
A digital image can be represented as a matrix.
© 2002 by Yu Hen Hu9ECE533 Digital Image Processing
Spatial and Gray Level Resolution
Spatial resolution: » # of samples per unit
length or area» DPI: dots per inch
specifies the size of an individual pixel
» If pixel size is kept constant, the size of an image will affect spatial resolution
Gray level resolution:» Number of bits per
pixel» Usually 8 bits» Color image has 3
image planes to yield 8 x 3 = 24 bits/pixel
» Too few levels may cause false contour
© 2002 by Yu Hen Hu10ECE533 Digital Image Processing
Same Pixel Size, different Sizes
© 2002 by Yu Hen Hu11ECE533 Digital Image Processing
Same Size, Different Pixel Sizes
© 2002 by Yu Hen Hu12ECE533 Digital Image Processing
Varying Gray Level Resolution
© 2002 by Yu Hen Hu13ECE533 Digital Image Processing
Size, Quantization Levels and Details
Isopreference curves
© 2002 by Yu Hen Hu14ECE533 Digital Image Processing
Aliasing: Moiré Effect
© 2002 by Yu Hen Hu15ECE533 Digital Image Processing
Zooming Zooming
© 2002 by Yu Hen Hu16ECE533 Digital Image Processing
Zooming and Interpolation