HDRI Photography

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HDRI Photography

Postby jamesfc on Wed Mar 25, 2009 4:09 pm

What the heck is HDRI photography?

I first learned about HDR images about 10 years ago when my 3D rendering program, Lightwave 3D, began offering it as an option for realistic lighting. In recent months, HDR is suddenly becoming more and more popular and is supported by a number of programs such as Photoshop CSx and specialty programs such as Photomatix.

Regular 8 bit images have a limited dynamic range of about 5 or 6 EV (exposure values). This means anything more than a couple of stops from the exposure point are either clipped highlights or go completely black. HDR images extend the dynamic range by taking a number of exposures which are later merged together into a single HDR image. That's where the special software comes in.

Unfortunately, there isn't a monitor made that can display the range of an HDR image, so, they have to be reduced back to a 16 or 8 bit image for viewing and printing. However, the photographer gets to decide how to map the tones in the final photograph. This image can end up wildly garrish, or ultra realistic. It's up to the photographer and the software to decide.

HDRI Motorcycle - 3 combined exposures
_MG_2526_5_4.jpg (74.79 KiB) Viewed 3398 times

My photo above of the motorcycle is an HDR image that consisted of 3 exposures (-1, 0 and +1) that were processed using Photomatix. I went for more realism in this shot, but notice the tires and the chrome reflections. There is a lot more detail present in these areas than would appear in a "normal" photograph.

I suggest you do an Internet search for HDR Images and you may be amazed at the dramatic (sometimes silly) effects that can be achieved with this method.

At a minimum you want to take 3 exposures - 1 over and 1 under your selected exposure and change the shutter speed, not the aperture. Some scenes may be better suited for 2 over and 2 under. Better yet, use 5, 6 or even 7 exposures (or more even!) if the scene has a really high contrast range. HDR images are best suited to high dynamic range scenes rather than scenes with low contrast.

To rapidly shoot my images, I found on my 5D MK II (should also work on the 40D and 50D) that by pressing the 'joystick' on the back of the camera, I get an info screen. It is very easy to select the AEB (Automatic Exposure Bracketing) setting and turn the finger dial by the shutter for the number of exposures you want. These cameras give you 3 exposures up to 2 stops over and under. If you would like more, press the middle of the thumb wheel, then rotate the thumb wheel on the back until the exposure compensation is below the "correct" exposure. The camera should be in rapid fire mode - hold down the shutter and fire off the three shots, then go back into the same screen and this time rotate the wheel until the range covers the higher end of the exposure spectrum, then fire again. Note that this method assumes you are shooting on a tripod! Also, make sure the custom function for AEB is set not to auto cancel!

On higher end cameras, such as my 1D MK II N, it will already allow me to set more than 3 bracket exposures.

Let me know if you have questions and post some of your experiments here!
Jim Caldwell
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Re: HDRI Photography

Postby aprillove20 on Wed Nov 10, 2010 10:21 pm

thanks for taking time to discuss. your effort are highly appreciated.
i hope you will share more of your idea. keep posted...
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Re: HDRI Photography

Postby rogerjackkson on Mon Feb 07, 2011 6:44 pm

Such a nice photo of that Harley-Davidson bike. I really like it. I also like to capture this type of bike's photo that looks very sexy. I appreciate for it. Keep posting.
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