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Digital Photography DeCal. EECS98 Nathan Yan. How it works. All cameras, film or digital, work the same: Photons are projected onto a photo-sensitive plane which records the light information. How it works. - PowerPoint PPT Presentation

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Digital Photography DeCalEECS98Nathan Yan

All cameras, film or digital, work the same:Photons are projected onto a photo-sensitive plane which records the light informationHow it works

How it worksBy confining light to only photons which pass through a certain point, we begin to resolve detail

Image processor

History of Camera Development Many pinhole-type cameras dating back to the 11th century Joseph Nipce recorded the first photograph in 1826, using a photo-sensitive silver/chalk mixture (8 hour exposure) Development of recording mediums more responsive to light: wet plates, dry plates George Eastman introduces photographic film in 1885, and debuts the Kodak camera in 1888 a cheap and easy to operate camera that began to popularize cameras Oskar Barnack developed the Leica camera in 1925, which popularized 35mm film standard Ihagee introduced the first single-lens reflex camera, Exakta, in 1933, allowing photographers to view image through the lens Auto-focus developed in the Konica C35AF in 1977History of Digital Camera Development Began with charged couple device (CCD) cameras that recorded to analog media Steve Sasson produced the first for Kodak in 1973 Solid state CCD that recorded output onto cassette tape Resolution: 10,000 pixels, or 0.01 megapixels First practical use in 1984, for journalism Canon RC-701 recorded images onto video floppies During 1984 Olympics images could be transmitted via telephone lines, and image quality (780x585, .4MP) was acceptable for newsprint JPEG image compression standard introduced in 1988 First true digital camera: Fuji DS-1P debuted in 1988, recording a computerized image file to onboard memory First camera with live image feed to LCD: Casio QV-10 in 1995 First professional digital SLR camera natively designed: 2.74MP Nikon D1 in 1999 First affordable consumer digital SLR: 6MP Canon Digital Rebel 300D in 2003 - $1000

Input:

Light photonsOutput:

Electrical signalsThe Imaging SensorSiSiSiSiSiPhotowellBucketloads of Electrons!Many electronsVoltage: HighImplication: Many photons detected, bright exposureResult: bright imageFew electronsVoltage: LowImplication: Few photons detected, dark exposureResult: dark imageMax electronsVoltage: MaxImplication: Max photons detected, brightest exposureResult: White imageNo electronsVoltage: ZeroImplication: No photons detected, darkest exposureResult: Black image

Bigger aperture = more light!ApertureLonger shutter speed (exposure time) = more light collected!Shutter speed

Electrical signalAccumulated chargeAmplifierVoltage MeasurementAmplified electrical signalISO is a sensitivity higher ISO means more signal (brightness) for the input (light) you actually getISO sensitivityx010x010x100x111x111x111x111x111x000x000x100x110x100x111x111x111

Use software to multiply the pixel values2x4x8x16xDigital Multiplication

SiSiSi

101010100100Image processor

PhotonsPhotoelectronsElectrical signalAccumulated chargeDigital representation of electrical signalImage fileAmplifierAnalog-to-Digital ConverterAmplified electrical signal

PhotonsElectronsVoltage ReadingVoltage SignalImage BrightnessShutter speedApertureQuantum efficiencySignal AmplificationDigital MultiplicationExposure StopsStopsExposureShutter speedApertureISO sensitivity-41/16x1/1600sf/22ISO50-31/8x1/800sf/16ISO100-21/4x1/400sf/11ISO200-11/2x1/200sf/8.0ISO40001x1/100sf/5.6ISO800+12x1/50sf/4.0ISO1600+24x1/25sf/2.8ISO3200+38x1/12sf/2.0ISO6400+416x1/6sf/1.4ISO12800