Procesamiento De Imagenes En Matlab
Páginas: 7 (1683 palabras)
Publicado: 7 de julio de 2012
Digital Image Processing Using Matlab
Haris Papasaika-Hanusch Institute of Geodesy and Photogrammetry, ETH Zurich haris@geod.baug.ethz.ch
Images and Digital Images
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A digital image differs from a photo in that the values are all discrete. Usually they take on only integer values. A digital image can be considered as a large array of discrete dots, each of which has a brightnessassociated with it. These dots are called picture elements, or more simply pixels. The pixels surrounding a given pixel constitute its neighborhood A neighborhood can be characterized by its shape in the same way as a matrix: we can speak of a 3x3 neighborhood, or of a 5x7 neighborhood.
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Digital Image Processing Using Matlab
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Digital Image Processing Using Matlab
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Aspectsof Image Processing
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Image Enhancement: Processing an image so that the result is more suitable for a particular application. (sharpening or deblurring an out of focus image, highlighting edges, improving image contrast, or brightening an image, removing noise) Image Restoration: This may be considered as reversing the damage done to an image by a known cause. (removing of blur caused bylinear motion, removal of optical distortions) Image Segmentation: This involves subdividing an image into constituent parts, or isolating certain aspects of an image. (finding lines, circles, or particular shapes in an image, in an aerial photograph, identifying cars, trees, buildings, or roads.
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Digital Image Processing Using Matlab
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Types of Digital Images
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Binary: Eachpixel is just black or white. Since there are only two possible values for each pixel (0,1), we only need one bit per pixel. Grayscale: Each pixel is a shade of gray, normally from 0 (black) to 255 (white). This range means that each pixel can be represented by eight bits, or exactly one byte. Other greyscale ranges are used, but generally they are a power of 2. True Color, or RGB: Each pixel has aparticular color; that color is described by the amount of red, green and blue in it. If each of these components has a range 0–255, this gives a total of 2563 different possible colors. Such an image is a “stack” of three matrices; representing the red, green and blue values for each pixel. This means that for every pixel there correspond 3 values.
Digital Image Processing Using Matlab 5
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• Binary Image
Digital Image Processing Using Matlab
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Grayscale Image
Digital Image Processing Using Matlab
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Color Image
Digital Image Processing Using Matlab
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General Commands
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imread: Read an image figure: creates a figure on the screen. imshow(g): which displays the matrix g as an image. pixval on: turns on the pixel values in our figure.impixel(i,j): the command returns the value of the pixel (i,j) iminfo: Information about the image.
Digital Image Processing Using Matlab
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Command Window
Digital Image Processing Using Matlab
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Data Types
Digital Image Processing Using Matlab
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Image Information
Digital Image Processing Using Matlab
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Bit Planes
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Greyscale images can be transformed intoa sequence of binary images by breaking them up into their bit-planes. We consider the grey value of each pixel of an 8-bit image as an 8bit binary word. The 0th bit plane consists of the last bit of each grey value. Since this bit has the least effect (least significant bit plane). The 7th bit plane consists of the first bit in each value (most significant bit plane.
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DigitalImage Processing Using Matlab
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Initial Image
Digital Image Processing Using Matlab
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Bit Plane 0
Digital Image Processing Using Matlab
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Bit Plane 4
Digital Image Processing Using Matlab
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Bit Plane 7
Digital Image Processing Using Matlab
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Spatial Resolution
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Spatial resolution is the density of pixels over the image: the greater the...
Haris Papasaika-Hanusch Institute of Geodesy and Photogrammetry, ETH Zurich haris@geod.baug.ethz.ch
Images and Digital Images
•
A digital image differs from a photo in that the values are all discrete. Usually they take on only integer values. A digital image can be considered as a large array of discrete dots, each of which has a brightnessassociated with it. These dots are called picture elements, or more simply pixels. The pixels surrounding a given pixel constitute its neighborhood A neighborhood can be characterized by its shape in the same way as a matrix: we can speak of a 3x3 neighborhood, or of a 5x7 neighborhood.
• •
•
Digital Image Processing Using Matlab
2
Digital Image Processing Using Matlab
3
Aspectsof Image Processing
•
Image Enhancement: Processing an image so that the result is more suitable for a particular application. (sharpening or deblurring an out of focus image, highlighting edges, improving image contrast, or brightening an image, removing noise) Image Restoration: This may be considered as reversing the damage done to an image by a known cause. (removing of blur caused bylinear motion, removal of optical distortions) Image Segmentation: This involves subdividing an image into constituent parts, or isolating certain aspects of an image. (finding lines, circles, or particular shapes in an image, in an aerial photograph, identifying cars, trees, buildings, or roads.
•
•
Digital Image Processing Using Matlab
4
Types of Digital Images
•
Binary: Eachpixel is just black or white. Since there are only two possible values for each pixel (0,1), we only need one bit per pixel. Grayscale: Each pixel is a shade of gray, normally from 0 (black) to 255 (white). This range means that each pixel can be represented by eight bits, or exactly one byte. Other greyscale ranges are used, but generally they are a power of 2. True Color, or RGB: Each pixel has aparticular color; that color is described by the amount of red, green and blue in it. If each of these components has a range 0–255, this gives a total of 2563 different possible colors. Such an image is a “stack” of three matrices; representing the red, green and blue values for each pixel. This means that for every pixel there correspond 3 values.
Digital Image Processing Using Matlab 5
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• Binary Image
Digital Image Processing Using Matlab
6
Grayscale Image
Digital Image Processing Using Matlab
7
Color Image
Digital Image Processing Using Matlab
8
General Commands
• • • • • •
imread: Read an image figure: creates a figure on the screen. imshow(g): which displays the matrix g as an image. pixval on: turns on the pixel values in our figure.impixel(i,j): the command returns the value of the pixel (i,j) iminfo: Information about the image.
Digital Image Processing Using Matlab
9
Command Window
Digital Image Processing Using Matlab
10
Data Types
Digital Image Processing Using Matlab
11
Image Information
Digital Image Processing Using Matlab
12
Bit Planes
•
Greyscale images can be transformed intoa sequence of binary images by breaking them up into their bit-planes. We consider the grey value of each pixel of an 8-bit image as an 8bit binary word. The 0th bit plane consists of the last bit of each grey value. Since this bit has the least effect (least significant bit plane). The 7th bit plane consists of the first bit in each value (most significant bit plane.
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DigitalImage Processing Using Matlab
13
Initial Image
Digital Image Processing Using Matlab
14
Bit Plane 0
Digital Image Processing Using Matlab
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Bit Plane 4
Digital Image Processing Using Matlab
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Bit Plane 7
Digital Image Processing Using Matlab
17
Spatial Resolution
•
Spatial resolution is the density of pixels over the image: the greater the...
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