VIDEO AND IMAGE PROCESSING USING DSP AND PFGA. Chapter 1: Introduction to Image Processing. Contents

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1 ĐẠI HỌC QUỐC GIA TP.HỒ CHÍ MINH TRƯỜNG ĐẠI HỌC BÁCH KHOA KHOA ĐIỆN-ĐIỆN TỬ BỘ MÔN KỸ THUẬT ĐIỆN TỬ VIDEO AND IMAGE PROCESSING USING DSP AND PFGA Chapter 1: Introduction to Image Processing 1 Contents 1. Digital Image Formation 2 1

2 1. Digital Image Formation What is Digital Image Processing? Digital Image a two-dimensional function x and y are spatial coordinates The amplitude of f is called intensity or gray level at the point (x, y) Digital Image Processing process digital images by means of computer, it covers low-, mid-, and high-level processes low-level: inputs and outputs are images mid-level: outputs are attributes extracted from input images high-level: an ensemble of recognition of individual objects Pixel the elements of a digital image 3 1. Digital Image Formation The image function f c (x, y ) is still a function of and y0 2 [y0 min; y0 max] which vary in a continuum given by the respective intervals. 4 2

3 1. Digital Image Formation The representation of an M N numerical array as f (0,0) f (0,1)... f (0, N 1) f (1,0) f (1,1)... f (1, N 1) f ( x, y) = f ( M 1,0) f ( M 1,1)... f ( M 1, N 1) The representation of an M N numerical array in MATLAB f (1,1) f (1, 2)... f (1, N) f (2,1) f (2,2)... f (2, N) f ( x, y) = f ( M,1) f ( M,2)... f ( M, N) 5 Source of Images: Electromagnetic (EM) energy spectrum Acoustic Ultrasonic Electronic Synthetic images produced by computer 6 3

4 Examples: Gama- Ray Imaging 7 Examples: X-Ray Imaging 8 4

5 Transform illumination energy into digital images Single imaging sensor Line sensor Array sensor

6 coordinate amplitude

7 13 coordinate amplitude 14 7

8 coordinate amplitude

9 There are several standard ad non-standard color space RGB Spectral Primary Color Coordinate System: developed by the CIEin 1931 additive primary color based in human perception of colors wavelengths: red = 700nm; green: nm; blue = 435.8nm CIE: Commission Internationale de l'eclairage, based in Vienna, Austria 17 CMYK color model: Cyan, Magenta, Yellow, and Key (black) subtractive primary color C = 1.0 R uk b M= 1.0 G uk b Y = 1.0 B uk b K = bk b K b = MIN{1.0 R, 1.0 G, 1.0 B} 18 9

10 YIQ NTSC Transmission Color Coordinate System Y, called luma, is luminance of color I and Q, called chroma, describe the Hue and Saturation gamma-corrected RGB components 19 YUV EBU Transmission Color Coordinate System used in PAL/SECAM color television systems 20 10

11 YCbCr CCIR Rec. 601 Transmission Color Coordinate System The CCIR Rec.601 color coordinate system YCbCr is defined for the transmission of luma and chroma components coded in the integer range 0 to Class Assignment 1. Write a Matlabprogram to resample a 640x480 image to 160x120 image 2. Write a Matlabprogram to convert an 8-bit gray image to 4- bit gray image 3. Write a Matlabprogram to extract a 64x64 region at the center of a RGB color image. 4. Write a Matlabprogram to convert RGB to HSV 5. Write a Matlabprogram to convert RGB to YUV 6. Write a Matlabprogram to convert RGB to CMYK 22 11