Introduction to Computer VisionCS / ECE 181BThursday, April 1, 2004→ Course Details→ HW #0 and HW #1 are available.Course web site• http://www.ece.ucsb.edu/~manj/cs181b• Syllabus, schedule, lecture notes, assignments, links, etc.•Visit it regularly!Prereqs and background knowledge• E.g., I assume you know:– Basic linear algebra– Basic probability– Basic calculus– Programming languages (C, C++) or MATLAB♦First discussion session on MATLABYour job• You are expected to:– Attend the lectures and discussion sessions♦ You're responsible for everything that transpires in class anddiscussion session (not just what’s on the slides)– Keep up with the reading– Prepare: Read the posted slides before coming to class– Ask questions in class – participate!– Do the homework assignments on time and with integrity♦ “Honest effort” will get you credit– Check course web site often–Give us feedback during the quarterFirst part of course: Image Formation• Chapters refer to the Forsyth’s book– I will not be following the book closely.• Geometry of image formation- Chapters 1-3(Camera models and calibration)– Where?• Radiometry of image formation- Chapter 4–How bright?Cameras (real ones!)Digital images• We’re interested in digital images, which may come from– An image originally recorded on film♦ Digitized from negative or from print– Analog video camera♦ Digitized by frame grabber– Digital still camera or video camera– Sonar, radar, ladar (laser radar)– Various kinds of spectral or multispectral sensors♦ Infrared, X-ray, Landsat…• Normally, we’ll assume a digital camera (or digitizedanalog camera) to be our source, and most generally avideo camera (spatial and temporal sampling)What is a Camera?• A camera has manycomponents– Optics: lens, filters, prisms,mirrors, aperture– Imager: array of sensingelements (1D or 2D)– Scanning electronics– Signal processing– ADC: sampling, quantizing,encoding, compression♦ May be done byexternal frame grabber(“digitizer”)• And many descriptivefeatures– Imager type: CCD or CMOS– Imager number– SNR– Lens mount– Color or B/W– Analog or digital (output)– Frame rate– Manual/automatic controls– Shutter speeds– Size, weight–CostCamera output: A raster image• Raster scan – A series of horizontal scan lines, top tobottom– Progressive scan – Line 1, then line 2, then line 3, …– Interlaced scan – Odd lines then even linesRaster patternProgressive scanInterlaced scanExample: Sony CXC950Scan Type Interlaced area scanFrame Rate 30 HzCamera Resolution 640 X 480 Horizontal Frequency 15.734 kHzInterface Type AnalogAnalog Interfaces NTSC Composite; NTSCRGB; NTSC Y/CVideo Output Level 1 Vpp @ 75 OhmsBinning? NoVideo Color 3-CCD ColorSensor Type CCDCCD Sensor Size (in.) 1/2 in.Maximum EffectiveData Rate27.6 Mbytes/secWhite Balance YesSignal-to-noise ratio 60 dBGain (user selectable) 18 dBSpectral Sensitivity VisibleIntegration YesIntegration (Max Rate) 256 FramesExposure Time(Shutter speed)10 µs to 8.5 sAntiblooming NoAsynchronous Reset NoCamera Control Mechanical Switches; SerialControlDimensions 147 mm X 65 mm X 72 mmWeight 670 gPower Requirements +12V DCOperatingTemperature-5 C to 45 CStorage Temperature -20 C to 60 CLength of Warranty 1 year(s)Included Accessories (1) Lens Mount Cap, (1)Operating InstructionsReally 29.97 fps525 lines * 29.97= 640*480*3*29.979-10 bits/colorExample: Sony DFWV300Highlights:• IEEE1394-1995 Standard for a High Performance Serial Bus• VGA (640 x 480) resolution Non-Compressed YUV Digital Output• 30 fps Full Motion Picture• DSP• 200 Mbps, High Speed Data Transfers• C Mount Optical InterfaceSharpness:AdjustableHue:AdjustableSaturation:AdjustableBrightness:AdjustablePower:Supplied through IEEE1394-1995 cable (8 to30vdc) 3WOperation Temperature:-10 to + 50°CDimension:45 x 44 x 100 mmWeight:200gInterface Format:IEEE 1394-1995Data Format:640 x 480 YUV (4 : 1 : 1), YUV 8 bit each320 x 240 YUV (4 : 2 : 2), YUV 8 bit each160 x 120 YUV (4 : 4 : 4), YUV 8 bit eachFrame Rate:3.75, 7.5, 15.0, 30.0 and One ShotImage Device:1/ 2" CCDMini. Sensitivity:6 Lux (F1.2)White Balance:ATW and Manual ControlShutter Speed:1/ 30 to 1/12000 sec.SpecificationsExample: Sony XC999Highlights:• 1/2" IT Hyper HAD CCD mounted• Ultra-compact and lightweight• CCD iris function• VBS and Y/C outputs• Can be used for various applications without CCU• External synchronization• RGB output (with CMA-999)Video output signals:VBS, Y/ C selected with the switchS/ N ratio:48 dB or moreElectronic shutter speed:1/ 1000 sec., CCD IRIS, FLWhite balance:ATW, 3200K, 5600K, Manual (R.B)Gain control:AGC, 0 dBPower requirements:DC 10.5 ~ 15V (typical 12V)Power consumptions:3.5WDimensions:22 (W) x 22 (H) x 120 (D) mm(excluding projecting parts)Weight:about 99gMTBF:34,800 Hrs.Pick up device:1/2" IT Hyper HAD CCDColor filter:Complementary color mosaicEffective picture elements:768 (H) x 494 (V)Lens mount:NF mount (Can be converted into a C mount)Synchronization:Internal/ External (auto)External sync. system:HD/ VD (2 ~ 4Vp-p), VSExternal sync. frequency:± 50ppmHorizontal resolution:470 TV linesMinimum illumination:4.5 Lux (F1.2, AGC)Sensitivity:2,000 lux F5.6 (3,200K, 0dB)SpecificationsPixels• Each line of the image comprises manypicture elements, or pixels– Typically 8-12 bits (grayscale) or 24 bits (color)• A 640x480 image:– 480 rows and 640 columns– 480 lines each with 640 pixels– 640x480 = 307,200 pixels• At 8 bits per pixel, 30 images per second– 640x480x8x30 = 73.7 Mbps or 9.2 MBs• At 24 bits per pixel (color)– 640x480x24x30 = 221 Mbps or 27.6 MBsAspect ratio• Image aspect ratio – width to height ratio of the raster– 4:3 for TV, 16:9 for HDTV, 1.85:1 to 2.35:1 for movies– We also care about pixel aspect ratio (not the same thing)♦ Square or non-square pixelsSensor, Imager, Pixel• An imager (sensor array) typically comprises n x m sensors– 320x240 to 7000x9000 or more (high end astronomy)– Sensor sizes range from 15x15µm down to 3x3 µm or smaller• Each sensor contains a photodetector and devices forreadout• Technically:– Imager – a rectangular array of sensors upon which the scene isfocused (photosensor array)– Sensor (photosensor) – a single photosensitive element thatgenerates and stores an electric charge when illuminated. Usuallyincludes the circuitry that stores and
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