DIGITAL

PHOT GRAPHY

TOPIC: HDR PHOTOGRAPHYAMITY UNIVERSITY, UTTAR PRADESH

BACHELORS IN JOURNALISM AND MASS

COMMUNICATION

A Amit Kumar Dash Presentation

What is HDR Photography?

High dynamic range imaging (HDRI or HDR) is a set of

methods used in imaging and photography to allow a greater

dynamic range between the lightest and darkest areas of an

image than current standard digital imaging methods or

photographic methods.

HDR images can represent more accurately the range of

intensity levels found in real scenes, from direct sunlight to

faint starlight, and is often captured by way of a plurality of

differently exposed pictures of the same subject matter.

In simpler terms, HDR is a range of methods to provide higher

dynamic range from the imaging process. Non-HDR cameras take

pictures at one exposure level with a limited contrast range. This

results in the loss of detail in bright or dark areas of a picture,

depending on whether the camera had a low or high exposure

setting.

HDR compensates for this loss of detail by taking multiple

pictures at different exposure levels and intelligently stitching

them together to produce a picture that is representative in

both dark and bright areas.

Non-HDR cameras take photographs with a limited exposure range,

resulting in the loss of detail in bright or dark areas. HDR compensates for

this loss of detail by capturing multiple photographs at different exposure

levels and combining them to produce a photograph representative of a

broader tonal range. HDR images are also acquired using special image

sensors.

The two primary types of HDR images are:

1. Computer Renderings

2. Resulting from Merging Multiple Low-Dynamic-Range

There are two broad rendering intents of HDR processing

Photorealistic and Artistic

• Photorealistic attempts to reveal what the scene looked like to the makers eye.

• Artistic meant to be more like “Art” and not necessarily represent the actual

scene.

Some example scenes that are generally good for HDR:

• Bright sunny day

• Night scenes

• Indoor scenes where bright sun is visible through windows

• Outdoor scenes with highly reflective elements such as water falls.

General Workflow:

• Initial capture - bracketed range or single image (some HDR processing

on a single exposure is possible)

• Minimal image prep in RAW development or pre-HDR processing of

captured TIFFs

• Save As TIFF files

• HDR software tools to create a combined image of high dynamic range

exposures (in 32 bit and then converted by software to16 bit)

• Final image processing in Photo Shop

• Save completed image ready for output

Major HDR Processing Software Suppliers:

Commercial Software:

1. HDR Soft - Photomatix Pro

2. Nik Software - HDR Efex Pro

3. Adobe - Photo Shop HDR Merge

Free Software:

1. HDR PhotoEngine

2. Essential HDR

3. FDRTools Basic

4. Picturenaut

In Photography, dynamic range is measured in EV differences (known as stops)

between the brightest and darkest parts of the image that show detail.

An increase of one EV, or one stop, represents a doubling of the amount of light.

Device Stop

LCD 9.5

NEGATIVE FILM 13

HUMAN EYE 10-14

DSLR 14.4

Dynamic ranges of common devices

Mid-nineteenth century

The idea of using several exposures to fix a too-extreme range

of luminance was pioneered as early as the 1850s by Gustave Le Gray to

render seascapes showing both the sky and the sea.

Such rendering was impossible at the time using standard methods, the

luminosity range being too extreme. Le Gray used one negative for the sky,

and another one with a longer exposure for the sea, and combined the two

into one picture in positive.

Mid- twentieth century

Manual tone mapping was accomplished by dodging and burning – selectively increasing

or decreasing the exposure of regions of the photograph to yield better tonality

reproduction. This is effective because the dynamic range of the negative is significantly

higher than would be available on the finished positive paper print when that is exposed via

the negative in a uniform manner.

An excellent example is the photograph Schweitzer at the Lamp by W. Eugene Smith, from

his 1954 photo essay A Man of Mercy on Dr. Albert Schweitzer and his humanitarian work

in French Equatorial Africa.

The image took 5 days to reproduce the tonal range of the scene, which ranges from a

bright lamp (relative to the scene) to a dark shadow.