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Computer_Vision-Lecture 2- Revision on Image.pdf
- 1. COMPUTER VISION LEC2: REVISIONON IMAGE DR. SAFYNAZ ABDEL-FATTAH LECTURE 2
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- 3. CONTENTS (c) 2018, Dr.R. Elias Images 2
- 4. 2D AND 3D CARTESIANCOORDINATES 3D Cartesian coordinate system Images 4 2D Cartesian coordinate system
- 5. RIGHT- AND LEFT-HANDED3D COORDINATE SYSTEMS Right-handed system Images 5 Left-handed system
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- 8. DIGITAL IMAGES Does acolor have a depth ? ! Images 8
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- 10. REPRESENTING DIGITAL IMAGES •The image representation is by an array (matrix) composed of the numerical values of f(x,y). This is the representation used for computer processing. • In equation form, we write the representation of an m*n numerical array as • The right side of this equation is a digital image represented as an array of real numbers. Each element of this array is called an image element, picture element, pixel, or pel.
- 11. REPRESENTING DIGITAL IMAGES •The origin of an image at the top left corner • Choosing the origin of f(x,y) at that point makes sense mathematically because digital images in reality are matrices. • The center of an m × n digital image with origin at (0,0) and range to (m − 1, n − 1) is obtained by dividing m and n by 2 and rounding down to the nearest integer. • Ex, the center of an image of size 1023 × 1024 is at (511 ,512 ). • The numbers of m and n have to be positive integers.
- 12. PIXELS! • Every pixelhas # of bits (k) So, the gray intensities ( L ) that the pixel can hold, is calculated according to a number of pixels it has (k). L= 2k • Q: suppose a pixel has 1 bit, how many gray levels can it represent? Answer: 2 intensity levels only, black and white. Bit (0,1) 0:black , 1: white • Q:suppose a pixel has 2 bit, how many gray levels can it represent? Answer: 4 gray intensity levels 2bit (00, 01, 10 ,11). • Now .. if we want to represent 256 intensities of grayscale, how many bits do we need? Answer: 8 bits which represents: 28=256
- 13. SPATIAL AND INTENSITYRESOLUTION • Intensity resolution: Is the smallest discernible change in intensity level. () The more intensity levels used, the finer the level of detail discernable in an image. Intensity level resolution is usually given in terms of the number of bits used to store each intensity level. Based on hardware considerations, the number of intensity levels usually is an integer power of two. The most common number is 8 bits, with 16 bits being used in some applications in which enhancement of specific intensity ranges is necessary. Intensity quantization using 32 bits is rare. Number of Bits Intensity Levels Examples 1 2 0, 1 2 4 00, 01, 10, 11 4 16 0000, 0101, 1111 8 256 00110011, 01010101 16 65,536 1010101010101010
- 14. NUMBER OF STORAGEOF BITS
- 15. NUMBER OF STORAGEOF BITS
- 16. EFFECTS OF VARYINGTHE NUMBER OF INTENSITY LEVELS IN A DIGITAL IMAGE • 256 grey levels (8 bits per 128 grey levels (7 bpp) 64 grey levels (6 bpp) 16 grey levels (4 bpp) 32 grey levels (5 bpp) 8 grey levels (3 bpp) 4 grey levels (2 bpp) 2 grey levels (1 bpp)
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- 22. IMAGE TYPES :BINARY IMAGE
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- 25. DIGITAL IMAGE TYPES: INTENSITY IMAGE
- 26. COLOR IMAGES AND RGBCOLOR SPACE Images 26
- 27. COLOR IMAGES AND RGBCOLOR SPACE Images 27
- 28. COLOR IMAGES • Colorimage: A color image contains pixels each of which holds three intensity values corresponding to the red, green, and blue or( RGB)
- 29. DIGITAL IMAGE TYPES: RGB IMAGE
- 30. 24-BIT COLOR IMAGES Images30 Concept!
- 31. 24-BIT COLOR IMAGES Images31 Concept!
- 32. 8-BIT COLOR IMAGESConcept! Images 32
- 33. 8-BIT COLOR IMAGESConcept! Images 33
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- 35. IMAGE FILE FORMATSFormat! Images 35
- 36. FORMAT EXAMPLE: BMP FORMATFormat! Images 36
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- 38. BMP FORMAT: INFO ORDIB HEADER Format! Images 38
- 39. BMP FORMAT: INFO ORDIB HEADER Format! Images 39
- 40. BMP FORMAT: IMAGE DATAFormat! Images 40
- 41. BMP FORMAT: COLOR PALETTEFormat! Images 41
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- 43. BMP FORMAT: AN EXAMPLEFormat! Images 43
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