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2. Camera, Optics 2.2. Camera,Camera, OpticsOptics E-mail: [email protected] http://web.yonsei.ac.kr/hgjung 2.1.2.1. CameraCamera E-mail: [email protected] http://web.yonsei.ac.kr/hgjung Virtual image, perspective projection [1] E-mail: [email protected] http://web.yonsei.ac.kr/hgjung How large a pinhole? [1] E-mail: [email protected] http://web.yonsei.ac.kr/hgjung Shrinking the aperture [2] E-mail: [email protected] http://web.yonsei.ac.kr/hgjung Shrinking the aperture [2] E-mail: [email protected] http://web.yonsei.ac.kr/hgjung Same function with large pinhole: Lens [1] E-mail: [email protected] http://web.yonsei.ac.kr/hgjung 광전효과광전효과(Photoelectric(Photoelectric Effect)Effect) In the photoelectric effect, electrons are emitted from matter (metals and non-metallic solids, liquids or gases) as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as "photoelectrons". Symbol for photodiode. Light-matter interaction http://en.wikipedia.org/wiki/Photoelectric E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ImageImage SensorSensor http://www.rocketroberts.com/astro/ccd_fundamentals.htm E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ImageImage SensorSensor An image sensor is a device that converts an optical image to an electric signal. It is used mostly in digital cameras and other imaging devices. Early sensors were video camera tubes but a modern one is typically a charge-coupled device (CCD) or a complementary metal– oxide–semiconductor (CMOS) active pixel sensor. A CCD image sensor on a flexible circuit board http://en.wikipedia.org/wiki/Image_sensor E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ImageImage Sensor:Sensor: CCDCCD A charge-coupled device (CCD) is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time. CCDs move charge between capacitive bins in the device, with the shift allowing for the transfer of charge between bins. Often the device is integrated with an image sensor, such as a photoelectric device to produce the charge that is being read, thus making the CCD a major technology for digital imaging. The charge packets (electrons, blue) are collected in potential wells (yellow) created by applying positive voltage at the gate electrodes (G). Applying positive voltage to the gate electrode in the correct sequence transfers the charge packets. http://en.wikipedia.org/wiki/Charge-coupled_device E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ImageImage Sensor:Sensor: CCDCCD Vertical smear. http://en.wikipedia.org/wiki/Charge-coupled_device E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ImageImage Sensor:Sensor: CMOS,CMOS, APSAPS (Active(Active PixelPixel Senor)Senor) An active-pixel sensor (APS), also commonly written active pixel sensor, is an image sensor consisting of an integrated circuit containing an array of pixel sensors, each pixel containing a photodetector and an active amplifier. There are many types of active pixel sensors including the CMOS APS used most commonly in cell phone cameras, web cameras and in some DSLRs. Such an image sensor is produced by a CMOS process (and is hence also known as a CMOS sensor), and has emerged as an alternative to charge-coupled device (CCD) imager sensors. A three-transistor active pixel sensor. http://en.wikipedia.org/wiki/Active_pixel_sensor E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ImageImage Sensor:Sensor: CMOS,CMOS, APSAPS (Active(Active PixelPixel Senor)Senor) 강문식, 신경욱, “IT CookBook, 전자회로: 핵심 개념부터 응용까지,” 한빛미디어. E-mail: [email protected] http://web.yonsei.ac.kr/hgjung InterlacedInterlaced .vs..vs. ProgressiveProgressive ScanScan With progressive scan, an image is captured, transmitted, and displayed in a path similar to text on a page: line by line, from top to bottom. The interlaced scan pattern in a CRT (cathode ray tube) display completes such a scan too, but only for every second line. This is carried out from the top left corner to the bottom right corner of a CRT display. This process is repeated again, only this time starting at the second row, in order to fill in those particular gaps left behind while performing the first progressive scan on alternate rows only. When interlaced video is watched on a progressive monitor with very poor deinterlacing, it exhibits combing when there is movement between two fields of one frame. http://en.wikipedia.org/wiki/Interlaced_video E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ShutteringShuttering - Image sensor의 sensitivity좋아야 Shuttering speed 높일수있고 motion blur 줄일 수있음. - Rolling shutter .vs. global shuttering 노출의 동기화 global shuttering 선호 http://www.vision-systems.com/articles/print/volume-10/issue- 5/features/component-integration/auto-cameras-benefit-from- cmos-imagers.html E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ShutteringShuttering In photography, shutter speed is a common term used to discuss exposure time, the effective length of time a camera's shutter is open. The total exposure is proportional to this exposure time, or duration of light reaching the film or image sensor. 짧은 shuttering 선호 Shutter speed can have a dramatic impact on A pinwheel photographed at three different the appearance of moving objects. Changes in shutter speeds background blurring are apparent from the need to adjust the aperture size to achieve proper exposure. 화면이 어두워질 수 있음 Sensitivity 좋은 소자 필요 A demonstration of the effect of exposure in night photography. Longer shutter speeds result in increased exposure. http://en.wikipedia.org/wiki/Shutter_speed E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ShutteringShuttering Rolling shutter (also known as line scan) is a method of image acquisition in which each frame is recorded not from a snapshot of a single point in time, but rather by scanning across the frame either vertically or horizontally. In other words, not all parts of the image are recorded at exactly the same time, even though the whole frame is displayed at the same time during playback. This in contrast with global shutter in which the entire frame is exposed for the same time window. This produces predictable distortions of fast-moving objects or when the sensor captures rapid flashes of light. Rolling Shutter Frame (Global) Shutter http://www.ptgrey.com/support/kb/index.asp?a=4&q=115 E-mail: [email protected] http://web.yonsei.ac.kr/hgjung ShutteringShuttering 고속으로 움직이면서 촬영하는 자동차응용의 경우, global shuttering 필요 http://en.wikipedia.org/wiki/Global_shutter E-mail: [email protected] http://web.yonsei.ac.kr/hgjung Shuttering:Shuttering: stoboscopicstoboscopic effecteffect Extraordinary stroboscopic effect Stroboscope: Grinder http://youtu.be/rVSh-au_9aM http://youtu.be/8mQaXaRVUoM E-mail: [email protected] http://web.yonsei.ac.kr/hgjung HDRC(HighHDRC(High DynamicDynamic RangeRange CMOS)CMOS) 카메라카메라 http://www.vision-systems.com/articles/print/volume-10/issue-5/features/component-integration/auto-cameras-benefit- from-cmos-imagers.html E-mail: [email protected] http://web.yonsei.ac.kr/hgjung 원적외선원적외선(FIR:(FIR: FarFar InfraRedInfraRed)) 카메라카메라 http://en.wikipedia.org/wiki/Electromagnetic_wave E-mail: [email protected] http://web.yonsei.ac.kr/hgjung 원적외선원적외선(FIR:(FIR: FarFar InfraRedInfraRed)) 카메라카메라 Flir Systems - "Path Finder" Automotive Infrared Camera http://youtu.be/PM9OcBpZaPo E-mail: [email protected] http://web.yonsei.ac.kr/hgjung 근적외선근적외선(NIR:(NIR: NearNear InfraRedInfraRed)) 카메라카메라 Active-infrared night vision : the camera illuminates the scene at infrared wavelengths invisible to the human eye. Despite a dark back-lit scene, active-infrared night vision delivers identifying details, as seen on the display monitor. http://en.wikipedia.org/wiki/Infrared E-mail: [email protected] http://web.yonsei.ac.kr/hgjung 근적외선근적외선(NIR:(NIR: NearNear InfraRedInfraRed)) 카메라카메라 E-mail: [email protected] http://web.yonsei.ac.kr/hgjung Color:Color: BayerBayer FilterFilter 어떻게 color 영상을 획득하나? http://en.wikipedia.org/wiki /Bayer_filter E-mail: [email protected] http://web.yonsei.ac.kr/hgjung Color:Color: BayerBayer FilterFilter Bayer Demosaicing http://en.wikipedia.org/wiki/Demosaicing E-mail: [email protected] http://web.yonsei.ac.kr/hgjung Color:Color: BayerBayer FilterFilter Bayer Demosaicing http://www.sharplabs.com/2pfc/Demosaicing%20One.html E-mail: [email protected] http://web.yonsei.ac.kr/hgjung Color:Color: ThreeThree--CCDCCD CameraCamera http://en.wikipedia.org/wiki/Three-CCD_camera E-mail: [email protected] http://web.yonsei.ac.kr/hgjung 원적외선원적외선(FIR:(FIR: FarFar InfraRedInfraRed)) 카메라카메라 열화상은 어떻게 온도를 측정하는가? http://globale- http://logicalmystery.blogspot.kr/2012/09/therm solutions.blogspot.kr/2012/11/thermographic- al-camerasreally-why-updated.html camera-thermal-imaging.html E-mail: [email protected] http://web.yonsei.ac.kr/hgjung 원적외선원적외선(FIR:(FIR: FarFar InfraRedInfraRed)) 카메라카메라 The radiant energy in the entire wavelength range (area beneath each curve) increases to the power of 4 of the temperature. These relationships were recognized by Stefan and Boltzmann in 1879 and illustrate that an unambiguous temperature can be measured from the radiation signal.
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