24th July 2008

High Dynamic Range

Last Updated: 28th July 2008

Written by: Siegfried Seierlein

Personally I enjoy technology, I am fascinated with the modern digital camera, software, PC’s and what they can do. I enjoy photography, but maybe not 100% from a artistic point of view, but more from technical point of view. The few years that I have been doing digital photography my general knowledge on photography has improved and today I better understand how to spot good quality daylight, unique opportunities and I better understand from what angle it will work best. These are things you can learn and if you like me not an artist then at least we can take a picture that’s composed according to basic rules.

With editing it is very much the same. Have you ever wondered, what should I do with the brush in Photoshop or its all OK to have a large collection of styles as long as you show me what to do with them. Have you tried to use the swirls and curls brush yet? Do you also have the magazine next to you or do it just happen by itself?

To get back to technology, I think its important to understand things like dynamic range, noise, exposure and a few more aspects if you want to enjoy a different side of photography. The advantage also is that you can easier spot when a reviewer is taking a chance....

Lets have a brief look at HDR and lets look at a few examples...


	Black and White HDR picture using only a few steps in Elements




		Black and White HDR with above Technique

Without using any special software or any special techniques these two pictures I thought were closer to the real thing I saw when taking them. That’s prior to turning them into B&W

With both these pictures I only used Photoshop to increase the shadows, to decrease the highlights and to correct the mid contrast. You can try it....don’t be afraid to move those sliders far out...

I selectively used saturation to bring back the colors to the picture. The car on the left did not look that great so I converted it to black and white and I thought its looks OK.

The top picture was done in CS3. All the pictures shown on this page were RAW and the camera use was the Olympus E-520. The top picture was 90% developed in the RAW editor and the remainder I did in Elements.




	Original Olympus E-520 picture exposed for highlights

The picture on the left is typically what we face today. The dynamic range of the digital cameras as just to small to capture all the contrasts and the different light conditions of a picture.

Reviewers are having a party telling readers that this camera can do that and the other can do this. No one ever tell the reader that the camera with the best score will still not be able to capture the scene on the left correctly. The white building in this picture for example over exposed even with the rest of the picture very dark.

There are many technical reasons for that and to discuss it will take a few more pages. The good news is there are a few techniques and software available to help the photographer.

What are these techniques and how do one use them? The first thing I think that is important is for you to know your camera. What is its limitations and what does the manufacturer offer to help you.

They all have something today to help the photographer to get better pictures. Olympus for example use SAT (Shadow Adjustment Technology).

I took the same RAW file as the top picture and in Studio (Olympus Editing Software) I used SAT plus the curves function to get the result on the right. I also selected the VIVID function in Studio.

The picture on the right is a HUGE improvement on pictures from the previous E-510 camera I think.

I can get a little excited when the reviewer do not tell the reader the exciting parts of a new camera, instead they show pictures at different ISO settings....like they did 5 years ago when noise was still a major issue. Some even today discuss the pixel size and try to link it to noise. For more info on noise visit the web site of any good noise software solution like Neat.

Its not only Olympus who has a great function like SAT today, its also Canon and Nikon and I think Sony and Pentax also has something similar.

To use it correctly and to really optimize the function its good to learn or to read up a little on the term “tone mapping”, the gamma setting and what the limitations are of a typical JPEG file.

I wrote a small article on Dynamic Range that could help you with the first few steps....


	E-520 with SAT plus Curves in Studio only

With the picture on the left I opened the original RAW file in Photoshop CS3. For those who do not know, the moment you open the RAW file in CS3 you immediately loose the SAT function plus you do not have any control on the in camera noise settings.

That’s not necessary bad....if you know what to do in CS3. If you don’t, then you might not get to the result I did on the left. So often I read on forums people say NOO do not use Studio its this and that....

The picture on the left required a good understanding of what dynamic range is, what are the current limitations and what can I do to recover the info available in the original RAW picture.

The picture is a little flat I think and if you look carefully then you will recognize but that’s how many digital pictures look today. You could also ask, but is that really a Oly picture, because Oly pictures have better colours...

Folks that is what happen when I squeeze a high contrast or dynamic range scene into a (8 bit) JPEG file. That is what many manufacturers do when they process the RAW data in the camera. The picture on the left will most probably score a 10,5 DR by the reviewer....the fact that its flat......


	Developed in CS3 RAW plus additional CS editing




			One RAW converted in 5 different exposures, edited with EasyHDR

	With the above picture I developed 5 differently exposed pictures with Studio from one RAW file. Each were 1 full stop apart from the other. That allowed me to have 5 differently exposed pictures and each had a different part of the picture perfectly exposed. I then used EasyHDR, a special HDR editing software to combine these 5 differently exposed pictures. The EasyHDR software take the correctly exposed part of each picture and then combine these parts into the perfect picture. When done it holds the complete contrast range of the original picture. The challenge for the user is then to decide what and how he likes to squeeze that contrast back into the JPEG file again. The software use typical terms and adjustments used by the manufacturers or the text books to adjust the picture. Without a basic understanding of these parameters it will be close to impossible to complete the process.



		E-520 RAW converted in 5 differently exposed pics, combined with Masks in PSE 6

The above picture consist of the same 5 pictures I used in EasyHDR to develop the HDR picture. In the above picture I then copied all the 5 pictures as layers into one picture. Using layer masks in Elements 6 I then processed layer for layer and deleted the parts of the picture I did not want in each layer. The final picture looks the most natural of the lot. In this example no tone curves, gamma or any other special curve was used. That said, folks its fun to play with HDR technology and its fun when you better understand how it all fits together. I hope this short article helps you to better understand what’s at stake and why you should be careful with reading to many reviews or opinions today. Best Siegfried




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