Part One
What is ‘dynamic range’? Wh t i ‘d i ’? The ratio between the maximum and minimum values
of a physical measurement f h i l t In photography, dynamic range is expressed in terms of f‐stop or exposure value (EV) f f t l (EV)
Media
Dynamic Range (approximately)
Sunlit Scene with Shadow
> 20 EV
The Human Eye
14 ‐ 24 EV
Negative Film
10.5 EV
Slide Film/DSLR
7 EV
Compact DC
6.6 EV
LCD Monitor
9 EV
Glossy Paper
7 6 EV 7.6 EV
Matte Paper
5.6 EV
What is ‘dynamic range’? Wh t i ‘d i ’? The ratio between the maximum and minimum values
of a physical measurement f h i l t In photography, dynamic range is expressed in terms of f‐stop or exposure value (EV) f f t l (EV) What is ‘high’ dynamic range? A light and dark ratio than goes beyond the coverage of our camera/monitor/printer (a relative term)
Quit shooting Q it h ti Wait for light condition to change Sacrifice either highlight or shadow Change composition (in camera or post‐processing) or
angle of shooting Reduce the dynamic range by using fill‐in flash, reflector, GND filter, etc Manual exposure blending/fusion Dodging and burning
Quit shooting Wait for light condition to change Sacrifice either highlight or shadow S ifi ith hi hli ht h d Change composition (in camera or post‐processing) or
angle of shooting l f h ti Reduce the dynamic range by using fill flash, reflector, fil filter, etc Manual exposure blending/fusion Dodging and burning The ‘HDR revolution’
HDR Software
A Single HDR File
HDR File
HDR Software
Tone Mapping
To scale down or compress the dynamic range of an
HDR image so that the resulting image can be presented on a monitor
Tone mapping/compression often creates visible artefacts like halo, glow and strong local contrast
To scale down and compress the dynamic range of an
HDR image so that the resulting image can be presented on a monitor Tone mapping often create visible artefacts like halo, glow and strong local contrast A brief history of HDR processing Tone mapping vs. exposure blending/fusion pp g p g
The idea of HDR is evolving‌. evolving
Stylistic
Realistic
* The idea of single image HDR processing
Part Two
Goal: Capture same image with different exposure G l C t i ith diff t Factors affecting exposure Aperture Shutter Speed ISO
Tripod Ti d Auto‐bracketing
Photomatix Ph t ti Nik HDR Efex Pro Photoshop
Background movement B k d t Moving object
HDR is more suitable for static scenes (but technology
keeps improving) HDR output is seldom the end of editing There is more than one way to tone map an image within a single program Each HDR program has its own character The artefacts created are considered good or bad depends on intention of the photographer There is no right or wrong about HDR but there is g good or bad use of the technique q
‘New technology does not automatically produce better images. HDR is simply a new tool that we can exploit and use to create images that were harder to achieve hi i the in h past’’ Uwe Steinmueller