High Dynamic RangeCave Photography

Mike Bedford

British Cave Research AssociationCave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

A miracle of optical engineering?

Perhaps …

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

… but this is a better one.

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Comparing Dynamic Range

Dynamic Range

Human Eye > 1,000,000 : 1

Human Eye (single scene) 10,000 : 1

High-contrast Daylight Scene 10,000 : 1

Point & Shoot Digital Camera 256 : 1

Good Quality Digital SLR Camera 2,000 : 1

JPEG Image File 256 : 1

Conclusion: Ordinary digital photography can’t properly capture some scenes or even compete with the human eye.

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Demonstrating the Problem

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

A Solution

+2EV

-2EV

0EV

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

The Process -Practically• Mount camera on Tripod (although software

can correct for alignment errors)• Take multiple exposures of same scene– Typically +2EV, 0EV & -2EV– or +2EV, +1EV, 0EV, -1EV & -2EV– although more stops overexposure might be

needed for caving use

• Use aperture priority• Process in software to create HDR image

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Tone Mapping• HDR software generates an HDR image• Can be stored using file formats designed specially

for HDR images • While Jpeg has dynamic range of 256 : 1

.dds, .exr, .hdr etc. offer 64,000 : 1 or more• But an LCD monitor provides 1,000 : 1 max• Prints offer an even lower dynamic range• Tone mapping is required to view on an ordinary

monitor or print• Provides scope for creativity

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Tone Mapping Example

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Tone Mapping Example

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Tone Mapping Example

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Tone Mapping Example

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

A Sunset

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

A Sunset

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

A Sunset

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Architectural Interiors

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Architectural Interiors

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Architectural Interiors

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

The Ultimate – Cave Entrances

• One of the highest dynamic range scenes we’re likely to encounter

• Inside looking out and outside looking in both present challenges

• Probably need to overexpose bymore than 2EV

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Browgill Cave

from the onsidelooking out

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Browgill Cave

from the insidelooking out

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Browgill Cave

from the insidelooking out

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Browgill Cave - from the outside looking in

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Browgill Cave

from the outsidelooking out

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Roger Kirk Cave

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Las Cuevas deSanto Tomás, Cuba

British Cave Research Association - Cave Technology Symposium 20119th April 2011, Ashbourne, Derbyshire

Thank you for ListeningAny Questions?