Smartphone Camera Technology


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Smartphone Camera Technology

  1. 1. Rough History of Photography Digital Sensors, Lenses, Zoom, Stabilization, Compression Best Practices for Shooting Video Week 4, University of Calgary Drama 571 Lecture prepared and presented by Dr. David Bunnell Smartphone Camera Technology Pelican Imaging's 16-lens camera module is designed for next-gen mobile devices coming in 2014. 1.
  2. 2. Rough History of Photography • Mid 1800s Silver nitrate glass plates • Early 1900s B&W silent “movies” • Mid 1900s Colour “talkies” B&W TVs • Late 1900s LCD TV’s Digital photography Cellular phones Internet • Early 2000s Digital movie making Smartphone cameras 2.
  3. 3. About Photographic Film Plastic coated with photosensitive emulsion. When light strikes the chemical it causes a reaction. Different formulas have different sensitivities to light. Film has a resolution of ~20 Megapixels. Film speed is a measure of how much light is required to cause the photochemical reaction. Slower, less reactive, film has finer grain (resolution) and better color fidelity. The camera shutter speed and aperture needs to be set within narrow range for successful photography. 3.
  4. 4. Digital Sensors • Electronics control exposure time (shutter sound is artificial) • Photons (light) energize electrons in CMOS (Complementary Metal Oxide Semiconductor) which can be collected by picture elements (pixels). • There are colour filters on each pixel to allow only Red, Blue, or Green (RGB) light to pass to the semiconductor element. • Smaller sensor chips have physically smaller pixels = more light is required to form an image. 4.
  5. 5. CMOS Sensor Chip Sony Image Sensor 5.
  6. 6. Apertures and Pixels Small aperture/lens = limited light, large depth of field Large aperture/lens = large amount light, small depth of field Small Sensor (slow film) needs more light Many pixels on small sensor = light spillage 6.
  7. 7. Basic Optics Object, aperture, Lens, shutter, sensor/film Small aperture gives greater depth of field 7.
  8. 8. Format Sensor size Pixel Pitch Camera 1/2.5” 5.76x4.29mm <1 micron Camera Phone 1/1.7” 7.6x5.7mm 1.7 microns Compact camera APS-C22.2x14.8- 5.7 microns Consumer DSLR 23.6x15.7mm Full Frame 36x24mm 8.4 microns Pro DSLR Sensors and Pixel Pitch 8.
  9. 9. Lenses 9.
  10. 10. Lenses Five element “Optical glass” lenses (with scratch resistant sapphire lens cover) Limited (no) anti-reflective coatings Purple haze on iPhone Digital (not optical) zoom 10.
  11. 11. Noise Sensors are made up of many tiny receptors, pixels, which record light. •Large pixels are more sensitive to light. – Camera makers boost the gain in small sensors to capture a usable image. •On large sensors, each pixel is walled off to prevent light from spilling over to adjacent pixels. – Small chips with high megapixel counts have light spillage (flares). – Transistors under each CMOS pixel generate noise. 11.
  12. 12. Digital Zoom • Smartphone cameras do not have optical zoom - digital zoom crops a region and expands the pixel size. No increase in resolution or number of pixels. 12.
  13. 13. Compression • Image is compressed to reduce storage requirements. • 8x8 blocks are averaged • Static areas (from frame to frame) copied. – Moving objects produce ghosts and blurring – Samsung allows editing of unwanted moving objects • Dedicated microprocessors in cameras can compress on-the-fly 13.
  14. 14. Infrared Sensitivity Camera sensors “see” a broader spectrum of light than the human eye. (Shine a TV remote control into your camera). The sensitivity to infrared may cause some color distortion. 14.
  15. 15. Image Stabilization Larger cameras may have “optical” stabilization where the sensor is mechanically moved to compensate for camera shake. Smaller cameras typically do not have mechanical stabilization and use “digital” stabilization that takes multiple shots and averages the pixels. Digital stabilization does NOT work for video 15.
  16. 16. 10 Best Practices for Shooting Video 1. Light your subject well • Avoid backlighting • Think of placing yourself (and the camera) between the light source and the subject • Fill in lighting with a big white cardboard, or use the golden hour 1. Charge your battery completely 2. Have lots of room on your micro SD card or internal memory for iPhone 3. Clean your lens 16.
  17. 17. Best Practices for Video (a few more) 5. Stabilize camera • For stabilization, stand with feet shoulder width apart and hold one hand underneath. • Use a tripod or rest camera on solid object • Minimize motion in poor lighting 5. Hold on your subject for at least 5 seconds (you can always edit out extra) 6. Move in close to subject • Don’t use digital zoom • Improves audio if using onboard camera mike 17.
  18. 18. Best Practices for Video (a few more) 8. Use a Zoom recorder or some other auxiliary microphone • Capture some room noise • Make sure you get mike tests and label the audio Take 1 Take 2 etc. and log the takes 8. Initiate your shot with by giving signals: • 3 – 2- (silence) then giving a finger gesture to start. (If you say “action” you will seldom get a good enough entry roll. • Label video with Take 1, Take 2 by using a clapper or sheet of paper before each take 18.
  19. 19. Best Practices for Video (a few more) 10. Give your shots texture and professionalism by using various shot angles, shot distances, camera movements and don’t be afraid to experiment. 19.