EasyHDR PRO is an image processing software that produces and tone maps High Dynamic
Range (HDR) images out of photo sequences taken with a digital camera. It is capable of importing
several image formats: JPEG, 24/48-bit TIFF and any RAW photo (thanks to integration with
DCRAW program). EasyHDR PRO can also import Radiance RGBE (*.hdr) or 96-bit TIFF HDR images
that were previously generated with any other HDR image processing software.
In order to produce a well exposed and dramatic-looking photo it is not always necessary to use
a series of differently exposed images. Sometimes just one photo is sufficient. That's why easyHDR
PRO gives you the ability to process a single image - the feature is called LDR (Low Dynamic Range)
enhancement.
What is a HDR image?
High Dynamic Range image covers much wider dynamic range (light to dark ratio) than
a normal digital camera can record (due to noise and overexposure). A HDR image is
created by blending an image sequence of photos taken at different exposure values
(various shutter speed, ISO sensitivity or aperture). Each photo in the sequence shall cover a
part of the dynamic range of the photographed scene. The resulting HDR image will therefore
contain the full information from all of the photos.
How to take an image sequence?
If you try to photograph a scene and get some unwanted over- or underexposured areas
you may consider taking a bracketed sequence that could be later blended to HDR and
processed. The easiest way to do so is to turn on autobracketing (AEB) in your digital camera,
set the number of photos in the sequence and the EV (Exposure Value) spacing. The 0EV
photo will be taken at the exposure time, ISO and the f-number measured by the camera as
the best for the particular scene. The other photos will be deliberately underexposed
(negative EV) or overexposed (positive EV) so they will contain details that are lost
in the 0EV photo due to noise and overexposure. The photographed scene should be static -
there should be no movement or light change during the photo sequence acquisition, otherwise
ghosting effect will be visible in the assembled HDR image. You should also use a tripod
to take the photo sequence, however EasyHDR PRO has a built-in auto-alignment feature that
compensates for shift and rotation between photos, so taking a photo free-hand won't
necessarily mean a bad result. If the autobracketing is not sufficient you may want to
manually vary the exposure time, with the constant ISO and f-number. When you i.e. take 3
photos at 1/200 (A), 1/100 (B) and 1/25 sec (C), this will mean that the photo (A) is
underexposed by 1 EV relatively to the photo (B) and the photo (C) is overexposed relatively
to (B) by 2EV - so you have a photo sequence: -1EV, 0EV and +2EV.
What is tone mapping?
In case of the assembled HDR images, the ratio of pixel value to real scene radiance is linear.
The CCD and CMOS sensors both have linear sensitivity too, but the photo taken
with a digital camera undergoes processing before it is stored as JPEG on the memory card.
That processing includes contrast (or dynamic range) compression, so the photo looks
natural when is displayed on a computer screen. We could do the same with the HDR images
(tone mapping with a global operator), but this will cause the loss of local contrast in the
output photos. That's why the special, local operators, are used to tone map HDR images.
Tone mapping is simply a procedure that allows the HDR images to be displayed on a screen
or printed.
What are the benefits of LDR enhancement with easyHDR PRO?
In many cases the photographed scenes do not characterize with very wide dynamic
range, so taking an image sequence in order to assemeble and tone map a HDR may be too much
effort. Also, by taking a RAW photo, instead of JPEG you can achieve a slightly higher
dynamic range, so a single photo may be sufficient (example).
Below you can see a single JPEG photo taken with Canon 350D and the result enhanced with
easyHDR PRO.
The history behind easyHDR PRO
The very first version of easyHDR was written in January 2006 in order to
process astrophotos like the Moon with a shining aureole, visible lunar seas and Earth's clouds. High interest
in the program pushed me to further enhance its abilities and add new features. Many easyHDR PRO users helped
me debug the program, suggested many new enhancements, committed their time to write tutorials and to translate
the program to many language versions. Also the editors of computer magazines found it interesting enough
to publish articles (like C'T and ComputerBild in Germany), as well as people from many countries, who
purchased the license. The program is still under development and is getting better and better. I'd like to
mention a couple of people who helped me with the program:
Robert Asano - for German translation, help with testing and sample photos,
Luke Bellani - for permission to use in the tutorial his photos of the Orion Nebula (M42),
Christian Carneiro - for preparing the Spanish and Portugiese (Brazil) tutorials, program and website translations,
Jörg Gravenhorst - for translating the program to German,
Lou Haskell and Allan Haskell - for help with the tutorial, testing, development and sample photos,
Alexandr V. Ivanov - for translating the short version of the website to Russian,
Alexander Kublitsky - for the Russian translation,
Rui M. Leal - for translating the program to Portuguese,
Drew Myers - for setting up a mirror download server,
Alessandro de Simone - for translating the program to Italian and writing an Italian version of the tutorial,
Rohn Stacks - for help with testing and development,
Anna Urbańska - for preparing the first translation to German,
Hartmut Wilhelm - for writing the German version of the tutorial,
All others who purchased the license, submitted bug reports and suggestions of further development as well as those who add photos into the easyHDR Flickr Group Pool.
Multicore CPUs are required for better performance.
Hard Disk
EasyHDR PRO uses temporary files that are created on the Hard Disk. In case of processing a set of three 10 MPix
JPEG photos at least 100 MB of free space is required. RAWs require twice as much.
Feature
Description
Supported image formats
(read)
JPEG, BMP, TIFF (24, 48 and 96 bit), Radiance RGBE
jhead.exe: to get basic EXIF headers from JPEG images
jpegtran.exe: to automatically and without quality loss rotate JPEGs while loading
About the author
My name is Bartłomiej Okonek (short form of the name is Bartek). I was born in 1983 in
Koszalin, in the north
of Poland, later moved to Leszno
and now I live in Wrocław, where
I also work as Software Engineer in an Irish company that produces high tech data acquisition systems.
In July, 2007 I graduated from Wroclaw University of Technology with a master's degree in Electrical Engineering
and Telecommunications. The subject of my Master's Thesis was: Effective implementation of High Dynamic
Range image generation and tone mapping algorithms in
FPGA devices.
During my studies I was also involved in
Student Space Exploration and Technology Initiative (SSETI), an European students' project endorsed
by the European Space Agency (ESA). One of my hobbies is astrophotography, but recently I do not have
many possibilities to do anything in that field.
