Introduction to Cameras Jim Rasche Samba Danfa Jaya Joseph 1

Outline Considerations in sensor selection: 1.How optics affect sensor selection 2.How an image is captured 3.Which type of camera sensor is best Setup and interactions: 1.File formats 2.Small sensors in embedded systems 3.Complex sensors in embedded systems 2

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 explained/ 3

Aperture and Depth of Field Controlling the focus of an image: Larger aperture = Narrow depth of field 4

-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. From Light to Charge 5

CCD vs CMOS CMOS pros: 1) 1/2 - 1/10 power of CCD 2) Single voltage input ~3.3V 3) Price and size CCD pros: 1) Signal / Noise ratio 2) Requires 15V, 3V, and -8V 3) Superior for low light [ 6

- 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 Digitization 7

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 8

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 9

RAW file: 1.Can capture 4096 or more shades of color per pixel 2.No in-camera processing of images 3.Post production JPEG file: 1.Can only capture 256 shades of color per pixel 2.Internal processing causes loss in color 3.Lossy compression RAW vs JPEG 10

RAW vs JPEG: File Size 11

Examples of Cameras in Embedded Systems

- Raw RGB565 output format only - Change frame rate ~ fps - Color adjustment - Luminescence adjustment - Price: $ Toshiba TCM8230MD (A) Ver Example: Simple Sensors (CMOS Camera 640x480) 13

Toshiba TCM8230MD (A) Ver voltage levels -8 data out pins -VD/HD lets user read image -I 2 C bus Interfacing with a Simple Sensor 14

Interfacing with a Simple Sensor Toshiba TCM8230MD (A) Ver V 1.5V Power: -PVDD(Sensor Array) = 2.8V -IOVDD (I/O) = 2.8V -PVDD (other) = 1.5V -Usual current draw = 40mA 2.8V 15

Interfacing with a Simple Sensor Toshiba TCM8230MD (A) Ver V 8 data out lines that transmit image data DOUT[7:0] Vertical/Horizontal pulse detection image assembly data 1.5V 16

Interfacing with a Simple Sensor 17

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

-Attach camera onto Arduino -Include the CMUcam4.h in the Arduino IDE libraries Connecting to Controller

Power the Board - Connect a 4-9V battery source capable of generating a 250 mA current 20

- 2 servo ports: Pan & Tilt for real world interaction Servos robot/ 21

Questions? 22