About easyHDR PRO

High Dynamic Range image processing software

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.

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.

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. Most ghosts however can be removed with easyHDR's manual or automatic ghost removal tools. You should use a tripod while taking the photo sequence, but hand-held photos that are misaligned can be aligned with easyHDR PRO, which features both: manual and automatic alignment methods. It is possible to compensate for shift, rotation and perspective. If the autobracketing is not sufficient you may want to manually vary the exposure time, preferably with constant ISO and f-number. When you take for example three 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. You can find more details about Exposure Value and a web-based calculator here.

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.

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 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 translating the program to German, help with testing and some 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 (first translations),
• József Tamás Herczeg - for translating the program to Hungarian,
• 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,
• Maciej B. Markiewicz - for translating the program to French,
• 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,
• Raffaele Valobra - for helping me understand color management,
• 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.

easyHDR PRO requirements and features

• DCRAW (dcraw.exe), by Dave Coffin: to convert RAW images to TIFF format
• EXIFtool (exiftool.exe), by Phil Harvey: to transfer EXIF headers from input to output image files
• LittleCMS (lcms2.dll), by Marti Maria: color management,
• FAST Corner Detection, by Edward Rosten: feature detection in automatic alignment.

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 for Bustec, a company that designs and 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.