HDRI
High Dynamic Range Imagery
(or just HDR)
When this presentation is over, I hope to have answered
two questions about HDR:
So I know what it stands for, but what the heck is HDR?
The technical definition
HDR plain talk
How can I make an HDR image?
The nuts and bolts basics
WHAT THE HECK IS HDR?
The Technical Definition
HDR is a set of techniques that allows a greater dynamic range of luminance
between light and dark areas of a scene than normal digital imaging techniques.
The intention of HDR is to accurately represent the wide range of intensity levels
found in real scenes ranging from direct sunlight to shadows. The process is
commonly used in real estate and architectural photography markets due to its
advantage of simultaneously and evenly exposing high and low lit areas within a
room. HDR has now gone beyond the quest to equally and perfectly expose a
photograph, to a realm of exaggeration that satisfies the artist within. As a result,
many photographers around the world have adopted this medium as a new form
of “photographic art”.
WHAT THE HECK IS HDR?
Plain Talk about HDR
I like to say that HDR is a composite of three or more photos of varied exposure
sandwiched together to make an evenly exposed photo
Think of the illustration to the left as a spectrum of light that you might
find in a room that is naturally lit from sunlight entering through a window.
Depending on the end result you’re after, this could be a situation in
which you’d want an evenly exposed picture. Because of the wide
range of dark & light areas within the frame, this could prove to be a
tough task without a flash. In a case such as this, some photographers
use the HDR process to reach an evenly exposed end result.
With HDR you would take at least 3 pictures at different exposures, one
evenly exposed, one over exposed, and one under exposed. Then you
take all 3 (or more) images and process them in a program to get your
desired HDR affect. More to come on this in a minute.
I like to use HDR for the dramatic and surreal affect it often produces rather
than using it as a tool to achieve natural looking results. Others prefer to
tone down the exaggerated look and maintain a more realistic picture.
HOW CAN I MAKE AN HDR IMAGE?
The Nuts & Bolts Basics
Essentials:
Camera with manual settings and bracketing capability
Tripod
Cable release
A computer program for creating your HDR image, such as Photomatix Pro
Taking HDR pictures:
Find some place that provides a wide spectrum of light and dark.
Good subjects are those which remain completely still. Rooms and
buildings are good examples. HDR images of plant life or nature are
difficult because of movement caused by the wind - but not impossible.
I have read, and discovered myself that generally speaking, people are
usually not the best subjects for HDR. These are only general guidelines,
keeping in mind that I consider this an art form - so anything goes if YOU like it.
HOW CAN I MAKE AN HDR IMAGE?
The Nuts & Bolts Basics
Taking your HDR pictures / continued:
Set your camera up as you would any other time, but with these exceptions:
Use automatic exposure bracketing if your camera has this option
Here you make the choice of whether or not you want to use 3 or more
images to process later on in your HDR program. I usually use 5 since it
provides some more flexibility during HDR processing. If you don’t have a
bracketing option you’ll just have to manually adjust the exposure
settings for each image in the series.
Set camera to aperture priority
To get your three (or more) varying exposures make SURE you adjust
shutter speed, NOT aperture. If you have multiple images of the same
subject with different aperture settings, the end HDR image will have fuzzy
edges. Remember - aperture priority for sharp HDR.
Attach cable release / or use camera timer
It is imperative that you avoid camera shake. The images you take MUST be very
Sharp. Prevent this by using your cable release. If you don’t have one, use your timer.
HOW CAN I MAKE AN HDR IMAGE?
The Nuts & Bolts Basics
Taking your HDR pictures / continued:
Attach your camera to the tripod, compose your shot and take your 3 or 5 shots.
- 2 stops - 1 stop +/- + 1 stop + 2 stops
You now have 3 or 5 images ready to process in your HDR program. I use photomatix
pro, which retails online for $99 at www.hdrsoft.com. It is very simple and user friendly.
It is also possible to use Photoshop, and other proprietary programs you can find online
through a google search of HDR software. You must have a computer program to complete
your HDR image. Which program you use - and the settings you use are completely
dependent on your personal taste. I rarely use the same setting for any two HDR images.
Good Luck
Creating
Your
Very Own
HDR Images!