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Introduction to Cameras

Introduction to Cameras. Jim Rasche Samba Danfa Jaya Joseph. Outline. Considerations in sensor selection : How optics affect sensor selection How an image is captured Which type of camera sensor is best Setup and interactions : File formats Small sensors in embedded systems

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Introduction to Cameras

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  1. Introduction to Cameras Jim Rasche Samba Danfa Jaya Joseph

  2. Outline • Considerations in sensor selection: • How optics affect sensor selection • How an image is captured • Which type of camera sensor is best • Setup and interactions: • File formats • Small sensors in embedded systems • Complex sensors in embedded systems

  3. Aperture and Light Aperture: The size of the hole that lets light into a device controlled by shutter - This is not made to be controlled so it is important to know the range of the shutter when choosing - The more light coming into a sensor, the brighter the image can be http://loweryl.wordpress.com/2012/10/03/aperture-fstop-explained/

  4. Aperture and Depth of Field Controlling the focus of an image: Larger aperture = Narrow depth of field • http://electronics.howstuffworks.com/cameras-photography/tips/aperture.htm • http://markfrommeltphotography.blogspot.com/

  5. From Light to Charge • Light from the lens falls onto a sensor array • Light at a specific point on the array passes through red, green,or blue filter on photodiode. http://digital.pho.to/

  6. CCD vs CMOS CCD pros: 1) Signal / Noise ratio 2) Requires 15V, 3V, and -8V 3) Superior for low light CMOS pros: 1) 1/2 - 1/10 power of CCD 2) Single voltage input ~3.3V 3) Price and size [http://cpn.canon-europe.com/content/education/infobank/capturing_the_image/ccd_and_cmos_sensors.do] http://www.electroiq.com/articles/stm/2011/03/cmos-image-sensors.html

  7. Digitization - The electric charge is converted into an analog voltage - It's amplified and sent to an Analog to Digital Converter (ADC) where it is digitized - The larger the charge, the larger the binary value readout - The file is a collection of numbers, representing location and brightness values for each square in an array http://carakerja-pengertian.blogspot.com/2011/03/cara-kerja-pengertian-kamera-digital.html

  8. Image Formats: RAW and JPEG - Captured images usually defaulted to either RAW or JPEG formats - RAW: specific format (tied to camera manufacturer and sensor) - Preserves most amount of info about an image - JPEG: default format, most popular image format used - Easy to edit/manipulate http://www.slrlounge.com/raw-vs-jpeg-jpg-the-ultimate-visual-guide

  9. Saving Files: RAW and JPEG - RAW image files have metadata attached to them • Two files are saved: one for the image data and another containing the camera settings • This allows for post production manipulation - When saving a JPEG file, all the information is saved in single file • Unchangeable

  10. RAW vsJPEG RAW file: • Can capture 4096 or more shades of color per pixel • No in-camera processing of images • Post production JPEG file: • Can only capture 256 shades of color per pixel • Internalprocessing causes loss in color • Lossycompression

  11. RAW vsJPEG:File Size

  12. Examples of Cameras in Embedded Systems http://diy-community.de/showthread.php?24138-Nachtsichtger%E4t http://www.sketchinginhardware.com/toolkits/lego-mindstorms/ http://brain.cc.kogakuin.ac.jp/~kanamaru/research/research-j.html

  13. Example: Simple Sensors(CMOS Camera 640x480) - Raw RGB565 output format only - Change frame rate ~15 - 30 fps - Color adjustment - Luminescence adjustment - Price: $9.95 https://www.sparkfun.com/products/8667 Toshiba TCM8230MD (A) Ver. 1.20 http://www.sparkfun.com/datasheets/Sensors/Imaging/TCM8230MD.pdf

  14. Interfacing with a Simple Sensor • 2 voltage levels • 8 data out pins • VD/HD lets user read image • I2C bus Toshiba TCM8230MD (A) Ver. 1.20 http://www.sparkfun.com/datasheets/Sensors/Imaging/TCM8230MD.pdf

  15. Interfacing with a Simple Sensor 2.8V 1.5V Power: • PVDD(Sensor Array) = 2.8V • IOVDD (I/O) = 2.8V • PVDD (other) = 1.5V • Usual current draw = 40mA 2.8V Toshiba TCM8230MD (A) Ver. 1.20 http://www.sparkfun.com/datasheets/Sensors/Imaging/TCM8230MD.pdf

  16. Interfacing with a Simple Sensor 2.8V 8 data out lines that transmit image data DOUT[7:0] Vertical/Horizontal pulse detection 1.5V 2.8V image assembly data Toshiba TCM8230MD (A) Ver. 1.20 http://www.sparkfun.com/datasheets/Sensors/Imaging/TCM8230MD.pdf

  17. Interfacing with a Simple Sensor http://www.sparkfun.com/datasheets/Sensors/Imaging/TCM8230MD.pdf

  18. Example: Complex Cameras(CMU Cam) - Arduino compatible - Image manipulation library - Frame differencing - Color tracking - B/W video output - SD card storage - Developed and tested firmware - Price: ~$135.95 http://www.cmucam.org/projects/cmucam4

  19. Connecting to Controller http://www.cmucam.org/projects/cmucam4/wiki/Lextronic_Camera • Attach camera onto Arduino • Include the CMUcam4.h in the Arduino IDE libraries http://www.cmucam.org/boards/5/topics/113

  20. Power the Board - Connect a 4-9V battery source capable of generating a 250 mA current http://www.cmucam.org/boards/5/topics/113

  21. Servos - 2 servo ports: Pan & Tilt for real world interaction • http://hacknmod.com/hack/remote-controlled-pan-and-tilt-robot/ http://www.cmucam.org/boards/5/topics/113

  22. Questions? http://xkcd.com/1014/

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