数字图像处理-冈萨雷斯-课件(英文)Chapter03-空域图像增强
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We can written as g(x, y) T f (x, y)
where f(x,y) is an original image, g(x,y) is an output and T[ ] is a function defined in the area around (x,y)
Note: T[ ] may have one input as a pixel value at (x,y) only or multiple inputs as pixels in neighbors of (x,y) depending in each function. Ex. Contrast enhancement uses a pixel value at (x,y) only for an input while smoothing filte use several pixels around (x,y) as inputs.
Image Negative
L-1 White
s L 1 r
Original digital mammogram
Output intensity
Black
0 Black
Input intensity
L-1 White
L = the number of gray levels
Negative digital
Images in the spatial domain are pictures in the xy plane
where the word “distance” is meaningful.
Using the Fourier
transform, the word “distance” is lost but the word “frequency” becomes alive.
In spatial domain we can represent an image by f(x,y) where x and y are coordinates along x and y axis with respect to an origin
There is duality between Spatial and Frequency Domains
(Images from Rafael C. Gonzalez and Richard E. Wood, Digital Image Processing, 2nd Edition.
Fra Baidu bibliotek
Image Enhancement Example
Original image
Enhanced image using Gamma correction
- Multiple pixel methods Examples Spatial filtering - Smoothing filters - Sharpening filters
Gray Level Transformation Transforms intensity of an original image into intensity of an output image using a function:
Digital Image Processing
Chapter 3: Image Enhancement in the
Spatial Domain
15 June 2007
Spatial Domain
What is spatial domain
The space where all pixels form an image
Types of Image Enhancement in the Spatial Domain
- Single pixel methods - Gray level transformations Example - Historgram equalization - Contrast stretching - Arithmetic/logic operations Examples - Image subtraction - Image averaging
Image Enhancement Image Enhancement means improvement of images to be suitable for specific applications. Example:
Note: each image enhancement technique that is suitable for one application may not be suitable for other applications.
s T(r)
where r = input intensity and s = output intensity
Example: Contrast enhancement
(Images from Rafael C. Gonzalez and Richard E. Wood, Digital Image Processing, 2nd Edition.
mammogram
(Images from Rafael C. Gonzalez and Richard E. Wood, Digital Image Processing, 2nd Edition.
Log Transformations
s c log(r 1)
(Images from Rafael C. Gonzalez and Richard E. Wood, Digital Image Processing, 2nd Edition.
Image Enhancement in the Spatial Domain
= Image enhancement using processes performed in the Spatial domain resulting in images in the Spatial domain.
where f(x,y) is an original image, g(x,y) is an output and T[ ] is a function defined in the area around (x,y)
Note: T[ ] may have one input as a pixel value at (x,y) only or multiple inputs as pixels in neighbors of (x,y) depending in each function. Ex. Contrast enhancement uses a pixel value at (x,y) only for an input while smoothing filte use several pixels around (x,y) as inputs.
Image Negative
L-1 White
s L 1 r
Original digital mammogram
Output intensity
Black
0 Black
Input intensity
L-1 White
L = the number of gray levels
Negative digital
Images in the spatial domain are pictures in the xy plane
where the word “distance” is meaningful.
Using the Fourier
transform, the word “distance” is lost but the word “frequency” becomes alive.
In spatial domain we can represent an image by f(x,y) where x and y are coordinates along x and y axis with respect to an origin
There is duality between Spatial and Frequency Domains
(Images from Rafael C. Gonzalez and Richard E. Wood, Digital Image Processing, 2nd Edition.
Fra Baidu bibliotek
Image Enhancement Example
Original image
Enhanced image using Gamma correction
- Multiple pixel methods Examples Spatial filtering - Smoothing filters - Sharpening filters
Gray Level Transformation Transforms intensity of an original image into intensity of an output image using a function:
Digital Image Processing
Chapter 3: Image Enhancement in the
Spatial Domain
15 June 2007
Spatial Domain
What is spatial domain
The space where all pixels form an image
Types of Image Enhancement in the Spatial Domain
- Single pixel methods - Gray level transformations Example - Historgram equalization - Contrast stretching - Arithmetic/logic operations Examples - Image subtraction - Image averaging
Image Enhancement Image Enhancement means improvement of images to be suitable for specific applications. Example:
Note: each image enhancement technique that is suitable for one application may not be suitable for other applications.
s T(r)
where r = input intensity and s = output intensity
Example: Contrast enhancement
(Images from Rafael C. Gonzalez and Richard E. Wood, Digital Image Processing, 2nd Edition.
mammogram
(Images from Rafael C. Gonzalez and Richard E. Wood, Digital Image Processing, 2nd Edition.
Log Transformations
s c log(r 1)
(Images from Rafael C. Gonzalez and Richard E. Wood, Digital Image Processing, 2nd Edition.
Image Enhancement in the Spatial Domain
= Image enhancement using processes performed in the Spatial domain resulting in images in the Spatial domain.