If you wonder what the heck is HDR, it is simply to create an artistic image out of ordinary shots (some samples are on my portofolio). For example, a Japanese tourist photography version of the Chicago Bean is below on the left and the HDR version of it is on the right.
Ok, without going much into technical details, HDR stands for High Dynamic Range. This technique allows to capture all details of the scene in both very bright and dark regions. In a scene with lots of bright lights and dark shadows e.g. sunset, our eyes can see the entire scene in detail but current cameras cannot capture all the details that we see. If you point your camera towards a bright point such as the sun, the details of shadows will be lost. If you point your camera towards shadows in such a scene, this time the details of highlight will be lost as seen in the sky of the regular Chicago Bean capture above. Using HDR, we can now easily capture details in both highlights and shadows. The good news is that everyone can do HDR photography with little to some effort. My main purpose here is to help you to discover the creativity in your photography. Nowadays, everyone has a digital camera and can count himself or herself as a photographer one way (a touristy one :)) or the other (an artistic one). HDR photography is a tool that will allow you to bring out your point of view and imagination to the same scene that is shot maybe a thousands times.
Ok, now if you do not want to read more about technical details, we can start our tutorial. Otherwise, just continue to read below to get more scientific details of the HDR photography.
My HDR tutorial contains 3 sections:
3) How to make HDR: This part is solely done with the computer and demonstrates maybe the most frustrating part of HDR photography in a very simple way so that you can start to get results right away.
Ok, lets get started ——————————>HDR tutorial
A bit more technical details about HDR photography:
In photography, the dynamic range (the range from the darkest to the brightest) is defined with the term EV (Exposure Value), or commonly known as stops. Each step change in EV or stops indicates doubling of the light. Below you can see a sample showing different exposures of the same scene with 2 EV steps which is the most common step size to make HDR photos. I shot this scene in Kauai, on Kalalau Trail, which is a 11 miles trail along the north cost of the island. As you can see, none of the photos below have complete presentation of the real scene. While the most left one ( -2 EV) has a lot of dark in the foreground, it preserves the details of highlight, here the the sky. On the other hand, the most right one (+2 EV) has blown out regions in the sky but it preserves the details in shadows, here the foreground trail. The photo in the center, which is the normal exposure one, misses a bit of details both in the foreground and the sky.
The digital cameras that we use have a lower dynamic range than what we can see with our eyes. Actually, the purpose of HDR photography is this: to bring the dynamic range of the captured images to the level that human eye can see and appreciate. I mean, none of the photos above is really what I saw there. Indeed, I could see the clouds as well as the bushes and road very well. An HDR version of the scene (see below) on the other hand would bring the details of both dark foreground bright background onto the same photo.
The chart below is showing the dynamic ranges:
|platform||dynamic range (contrast)||stops (that can cover indicated dynamic range)|
|Sunlight scene||100,000:1||17 EV (2 power 17=131,072 contrast)**|
|Human Eye||1,000,000:1||20 EV (2 power 20=1,048,576 contrast)|
|Digital SLR*||200:1- 2,000:1||8-11EV (2 power 11=2,048 contrast)|
|Negative film*||500:1- 2,000:1||9-11 EV|
|Glossy print*||50:1 – 200:1||6-8 EV|
|HDR photo as 32bit||unlimited (floating)||unlimited|
* is the maximum contrast that is produced by the current technology in 2010.
** since each EV is the doubling of the light amount, the calculation of the required EV stops is the power of 2.
I hope you could get a bit of the technical details above, for more technical brainwash, just go to this amazing article published in NatureScapes about 4 years ago and have a lot of detailed description.
If you are now ready to learn how to make HDR with the latest technology, let’s proceed to the action! ——————————>HDR tutorial