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Digital Camera Design

Digital Camera Design. Agenda. Digital video formats Image sensor technology Sensor interface with CoolRunner-II LCD CoolRunner-II system design. Digital Video. RGB Digitized version of analog RGB Most common in computer graphics YCrCb Digitized version of analog YUV and YPbPr

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Digital Camera Design

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  1. Digital Camera Design

  2. Agenda • Digital video formats • Image sensor technology • Sensor interface with CoolRunner-II • LCD • CoolRunner-II system design

  3. Digital Video • RGB • Digitized version of analog RGB • Most common in computer graphics • YCrCb • Digitized version of analog YUV and YPbPr • Format used by DVD and digital television

  4. Color Formats • RGB • Primary additive colors: red, green, & blue • Not efficient format for image processing • YCrCb • Luminance, Chroma Red, Chroma Blue • 8-bit ranges: Y (16 to 235), Cr & Cb (16 to 240) • 4:2:2 & 4:4:4 formats determine when Cr and Cb are sampled with Y

  5. Digital Video Capture • Video is series of still images (which each consist of lines of data) • Control signals: • VSYNC: Vertical sync (asserted during frame scan time) • HSYNC: Horizontal sync (asserted during line scan time) • BLANK: blanking • CLK: 1x or 2x sample clock • Digital output represents data of each pixel (RGB or YCrCb) • Data sampled on rising edge of sample clock

  6. Output Timing

  7. Image Sensors • CCD (charge-coupled device) vs. CMOS • CMOS manufacturers: Kodak, Micron, Hynix, OmniVision, Mitsubishi, ST Microelectronics, Toshiba

  8. MI-SOC-0343 • Complete CMOS image sensor camera-on-chip solution • “Active pixel” sensor architecture • Image sensor core + digital image processing technology • Outputs digitally processed RGB or YCrCb data • Programmable control registers • 640 x 480 VGA image array

  9. Active Pixel Architecture • CMOS sensorphotosite area breakdown25% = circuitrySensor fill factor = 75 % • Active pixel structure prevents background image noise Photodiode Active-Pixel Architecture Photogate Active-Pixel Architecture Image courtesy of Micron

  10. Sensing Color • Funnel light to the photosensitive portion of each pixel • CFA allows each RGB color to be measured independently Image courtesy of Micron

  11. GRGRGR GR BGBG BGBG GRGRGR GR BGBG BGBG GRGRGR GR BGBG BGBG Bayer CFA • Invented by Kodak • Able to separately measure red, green, & blue photons • 2x2 repeating arrangement • Output: sequential RGB (sRGB) Image courtesy of Micron

  12. MI-SOC-0343 Diagram Image Flow Processor Imager Core • Color Correction • Gamma Control • Sharpening Control • Saturation Control • AWB • AE • Defect Correction • Lens Detection Data Output& Timing Image Core Register Set Active Pixel Array (640 x 480) Image Flow Processor Register Set Analog Processing ADC Serial Interface(SCLK, SDATA)

  13. Image Flow Processor • Interpolates 1 color/pixel into 3-colors/pixel by filling in missing data based on adjacent pixels • Includes: lens shading, edge detection, aperture correction, color correction, AWB, AE, gamma correction, color saturation control, and zoom features • 77 addressable control registers • Output either 4:2:2 YCrCb (CCIR656) or 4:4:4 565RGB data

  14. CoolRunner-II Interface SHIP Interface Control Logic AddressCounter SCLK, SDATA Top LevelControl Logic MI-SOC-0343 PIX_CLK Image Grabber Control Logic FRAME_VALID SRAM Interface Logic LINE_VALID DOUT (7:0) Address / Data / Control 24 MHz Clock SRAM

  15. LCD • Best LCD solution for video application: color active matrix TFT • Transmissive or transflective polarization type • TFT modules offer sub-pixels (3 per pixel) to represent each RGB color • LCD (with an integrated driver) accessible via parallel data interface

  16. Optrex LCD • 6.4” Transmissive Color TFT • Dual CCT backlight • 640 x (RGB) x 480 (VGA format) • Thin form factor • Parallel 6-bit RGB data interface TimingLogic CCT Vertical IC Driver LCD Panel (640 x 480) Horizontal IC Driver CCT

  17. CoolRunner-II Interface CLK VSYNC Top LevelControl Logic LCD Interface Control Logic HSYNC OptrexT-51382D R (5:0) G (5:0) B (5:0) PWMControl Logic SRAM Interface Logic K2607 Inverter Address / Data / Control SRAM

  18. SHIP Interface Control Logic LCD Interface Control Logic System Design MainControl Logic LCDPanel CMOSImageSensor Image Grabber Control Logic PWMLogic Inverter SRAM Interface Logic SRAM

  19. SPEECH CODER RF AMP CHANNEL CODER CHANNEL SPREAD RF MOD A/D DRAM DSP SRAM DISPLAY DUPLEXER uP EPROM CMOSImageSensor KEYBOARD SPEECH DECODER RF RCV/AMP CHANNEL DECODE RAKE RCVR RF DEMOD D/A Cell Phone Camera Expansion

  20. Summary • CoolRunner-II allocation • Design uses a 384 macrocell device (with approx. 80% utilization) • Varies based on internal ROM size for CMOS image sensor register writes • CoolRunner-II is ideal for digital camera applications in portable and handheld devices • Provides a low power flexible interface with CMOS image sensors • Provides a low power data allocation and memory resource solution • CoolRunner-II can be used to extend existing design (ie. PDA, cell phone) and add digital camera functionality

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