Digital Imaging Processing Flashcards
Deals with an image which is composed of many image points
Digital Image Processing
Technology of applying a number of computer algorithms to process digital images
Digital image processing
Main purpose of processing
Allow to obtain an imahe of high quality or descriptive characteristics of the original image
Generated from continuous function, required for human viewing
Analog images
Numerical representation of the patient
Digital image
Related to brightness or color
Pixel value
Two domains
Spatial location
Spatial frequency
An image is described using right handed x-y coordinates
Spatial location domain
Images are acquired and described according to tge wavelength of the signal
Spatial frequency domain
Digitizing an image
Scanning
Sampling
Quantization
Image is divided into array of pixels
Scanning
Brightness level of each pixel is measured by PMT
Sampling
Process where the brightness levels obtained through sampling are assigned
Quantization
Integer
Gray level
Total number of gray level
Gray scale
Quantization occurs in
Analog digital converter
Divides the analog signal into equal parts depending on its bit capacity
Analog digital converter
Generate image that is more pleasing to the observer
Image enhancement
To improve the quality of images ggat have distortion or degradations
Image restoration
Allows measurements and statistics to be perform
Image analysis
To reduce the size of the image in order
Image compression
2 types of compression
Lossy
Lossless
Some loss image when decompressed
Lossy
No loss of information when decompressed
Lossless
Creates images from other images pr non images data
Image synthesis
Concepts of dogital imaging processing
Point processing operation
Local processing operation
Global processing operation
Geometric operation
Most frequent and simple used operation in digital diagnostic imaging
Point processing operation
3 methods of point processing
Histogram
Look up table
Windowing
Graph of number of pixels in the entire image
Histogram
Determines the number assigned to input pixel values
Look up table
Range of numbers, controls image contrast
Window width
Center of the range, controls brightness of tge image
Window level
Uses window width and window level
Windowing
The output image pixel value is obtained from a small area of pixels. It makes use of the image domains
Local processing operation
Value depends on a group of pixel in the input image
Spatial location filtering - convolution
Known as edge enhancement
Image in spatial location is converted to be in the spatial frequency
Spatial frequency high pass filtering
Output image will be blurred
Makes use of a low filter to operate on the input image with the goal
Spatial frequency low pass filtering
Intended to reduce noise and displayed brightness levels of pixel
Smoothing
Makes use of a blurred image produces from the low pass filtering process and subtracts it from the original to produce sharp
Spatial frequency processing : unsharp masking
Pixels are used to change the value of a pixel in the output image
Global processing operation
Allows user to change the position of pixel rather than brightness of tge pixels
Geometric operation
Range of technique that allows the user to change the appearance of a digital image
Image post processing
