Digital and Computational Photography

Transcription

1 Digital and Computational Photography Av: Piraachanna Kugathasan What is computational photography Digital photography: Simply replaces traditional sensors and recording by digital technology Involves only simple image processing Computational photography More elaborate image manipulation, more computation New types of media (panorama, 3D, etc.) Camera design that take computation into account

2 Computational photography Computational illumination Computational optics Computational processing Computational sensors Computational illumination Controlling photographic illumination in a structured fashion, then processing the captured images, to create new images Flash/no flash imaging Multi flash imaging Different exposures imaging Image based Relighting

3 Computational optics Capture of optically coded images, followed by computational decoding to produce new images Coded aperture imaging Coded exposure imaging light field photography Catadioptric imaging Wavefront coding Compressive imaging Computational processing Processing of non optically coded images to produce new images Panorama mosaicing Matte extraction Digital photomontage High dynamic range imaging All focus imaging

4 Computational sensors Detectors that combine sensing and processing, typically in hardware. Artificial retinas High dynamic range sensors Retinex sensors Tone mapping A simple example of global tone mapping filter

5 Defocus Matting Super resolution Get a sharp high resolution image from low resolution

6 The A Cam The A Cam is a collection of three video cameras that share a single center of projection by using a tree of beam splitters Results from the A Cam a)pinhole image of the A Cam, (b) background focused image, (c) foreground focused image, (d) automatically computed trimap, (e) the alpha matte at the A Cam resolution, (f) the super resolution alpha matte, and (g) super resolution alpha premultiplied foreground image composited with a new background.

7 Computational Imaging Two revolutions Revolution 1: The invention of optical instruments Imaging without optics

8 Imaging with optics Revolution 2: Electronic Recording

9 Electronic recording enables Electronic transmission (television) Multidimensional imaging (tomography) Feature extraction/enhancement Computational improvement of image metrics Enhanced resolution Extended depth of field Imaging of spectra, coherence and polarization features. History of traditional and digital photo

10 First production camera Daguerrotype Instant photography

11 First TV Transmission of moving images 1884 Paul Nipkow Using rotating disk with raster spiral But amplification problems Color TV First broadcast in 1951, CBS

12 Computer Graphics Computers to create image Sketchpad, 1961, Ivan Sutherland s MIT PhD thesis First digital camera 1975, Steve Sasson, Kodak Uses ccd from Fairchild semiconductor, A/D from Motorola,.01 megapixels, 23 second exposure, recorded on digital cassette

13 Paint program Dick Shoup: SuperPaint [ ] 8 bits Alvy Ray Smith (Pixar co founder): Paint [ ] 8 bits then 24 bits wardsmain.htm ain.htm Tom Porter: Paint Photoshop Thomas Knoll and John Knoll began development in 1987 Version 1.0 on Mac:

14 Internet photo browsing (Web browser that can display photos) Mosaics, NCSA, Urbana Champaign, 1992 Camera advice

15 Equipment Do get an SLR, compacts are way too limited Don't worry about brand Don't worry about the body, get the cheapest one Worry about lenses Zooms are convenient but quality can be a problem avoid the basic zoom, but the one above is usually great Maximum aperture matters (the smaller the number, the better) Get a prime in the 35 85mm range (cheap, high quality, wide aperture) 50mm f/1.8 (both Canon & Nikon) Get a tripod Get an external flash if you want to take event pictures And orient towards ceiling Good flash photography is very difficult Count 4k for camera+standard zoom+50mm Nikon most used, cheap, great body, good images Canon user friendly, good images Olympus Good system, but smaller sensor Konica Minolta Just announced they stop photography! Pentax Good entry camera Sigma Intriguing sensor (Foveon) Fuji One trick pony (the sensor) Nikon body Sony Very silent, good images, lot of functions Brands

16 Shooting Use aperture priority, work on depth of field Change your viewpoint Don't center things Learn to adjust ISO Shoot raw Check your histogram Editing (Photoshop) Crop to improve composition Manage contrast using curve and adjustment layers Sharpen a bit Convert to black and white with gradient map

17 Refs Wikipedia Google.com