Computer Science 194-23 The Art and Science of Digital Photography - - PowerPoint PPT Presentation

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Computer Science 194-23 The Art and Science of Digital Photography - - PowerPoint PPT Presentation

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Computer Science 194-23 The Art and Science of Digital Photography Lecture 6: The Histogram March 11, 2013 danallan@eecs.berkeley.edu barsky@cs.berkeley.edu michael.ball@berkeley.edu Staff email: cs194-23@imail.eecs.berkeley.edu 1 Image

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Computer Science 194-23 The Art and Science of Digital Photography

Lecture 6: The Histogram March 11, 2013 danallan@eecs.berkeley.edu barsky@cs.berkeley.edu michael.ball@berkeley.edu Staff email: cs194-23@imail.eecs.berkeley.edu

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Histograms

General Histogram

Image from http://en.wikipedia.org/wiki/Histogram 2

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Histograms

Digital Photography

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Black White Some Many

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Histograms

Total Underexposure

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Histograms

Total Overexposure

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Histograms

Well-exposed samples

Photo by Dan Armendariz, 2009 309s, ISO 100 6

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Histograms

Well-exposed samples

Photo by Dan Armendariz, 2007 1/1000s, ISO 400, f/5.6 7

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Histograms

Well-exposed samples

Photo by Dan Armendariz, 2007 8

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Histograms

Under-exposure

9 Photo by Dan Armendariz, 2005 8.0s, ISO 100, f/8

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Histograms

Over-exposure

10 Photo by Dan Armendariz, 2005 15.0s, ISO 100, f/16

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Histograms

Exposure Compensation

Photos by Dan Armendariz, 2005 Left: 1/80s, ISO 400, f/2.8, 0ev. Right: 1/80s, ISO 800, f/2.5, +1.3ev 11

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Histograms

Over- & Under-exposure

Photo by Dan Armendariz, 2006 1/80s, ISO 400, f/10 12

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Bits and Bytes

Refresher

Bit 0 or 1 Byte 8 bits

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Bits and Bytes

As related to histograms

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Black White 255

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Bits and Bytes

Bit Depth

JPEG Red Green Blue 8-bit 8-bit 8-bit 0 255 0 255 0 255

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Histograms

What about color?

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Red Green Blue ?

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The Eye

Luminance Detection

Image from http://en.wikipedia.org/wiki/Trichromacy 17

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The Eye

Luminance Detection

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Red Green Blue

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Luminance

Calculation

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Luminance ≈ 0.3 R + 0.59 G + 0.11 B

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Luminosity Histograms

DIY!

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Luminosity Histograms

DIY!

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Luminosity Histograms

DIY!

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Histograms

More than just Luminosity...

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Lum R B G

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Histograms

Luminosity, Colors, & RGB

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Lum Colors RGB

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Histograms

Luminosity, Colors, & RGB

25 Images from http://www.cambridgeincolour.com/tutorials/histograms2.htm

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Histograms

Luminosity, Colors, & RGB

26 Images from http://www.cambridgeincolour.com/tutorials/histograms2.htm

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Histograms

What is Black and White?

Photo by Dan Armendariz, 2006 1/80s, ISO 400, f/10 27

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Dynamic Range

The Eye

Image from http://en.wikipedia.org/wiki/Fovea 28

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Dynamic Range

Digital Cameras

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Pixel (“Bucket”) Photons (Light) Collected Light

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Dynamic Range

Simplified Calculation

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Dynamic Range = Biggest Signal (full “bucket”) Smallest detectable signal

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Dynamic Range

In Scenes

Photo by Dan Armendariz, 2006 1/80s, ISO 400, f/10 31

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Computer Science 194-23 The Art and Science of Digital Photography

Lecture 6: The Histogram March 11, 2013 danallan@eecs.berkeley.edu barsky@cs.berkeley.edu michael.ball@berkeley.edu Staff email: cs194-23@imail.eecs.berkeley.edu

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