HDR Basics

John_Walsh

Getting a grasp on HDR...

In its simplest form, I understand HDR to be "a blended image using the (best) lowlight/dark areas of an overexposed shot and the (best) hightlight/bright areas of an underexposed shot." Close?

And when discussing bracketing, what is the actual number applied (for +/- 2 etc). For example shooting at f/8 ISO 400 160 shutter.

ziggy53

The way that most people apply HDR ("High Dynamic Range" for those not familiar) is that, yes, tones that are close to or outside of (blown or plugged) normal camera single image dynamic range are mapped to an exposure within the camera's dynamic range. The exact blending process and degree of dynamic range compression are both subject to many variables.

The number of exposures acquired, the exposure differentials and the method of tone blending are also dependent on the scene requirements and artistic vision (how you, the photographer, want the scene portrayed) and the exact software and process involved. There is no single technology or process for HDR.

The method of image display can also be a consideration.

Ideally, only the time for exposure should be changed for each of the multiple exposures. If aperture, ISO or white balance changes between exposures, the process of blending is considerably more complicated.

Remember that if you create an HDR composite file, you need to represent the expanded DR in a lower DR medium, usually a computer display or print. Whether you compress all tones equally or selectively is part of the process, but it must be done.

Ohiohiker

I agree with Ziggy. I would take a look at Trey Ratcliff's HDR Tutorial. It is a good place to start and can be found at www.stuckincustoms.com. There are several other tutorials out there too. Matt Kloskowski has a good tutorial on Kelby training. Like everything else it comes with practice. To start with on your first attempts start at 1ev stops and go the extreme of shooting +3 to -3 stops. Go to your HDR Program(CS5, Photomatix etc) and load all the images, then load just -2 0 +2, then maybe -1 0 +1, you could even try -3 0 +3. Play around with the tone mapping settings etc till you find what you like. Then go out shoot a few more bracketed exposures and keep playing till you find what works best for you.

Hope this helps.

John_Walsh

So I've got a product shoot next week and wondered if HDR might be a good fit.

Manufacturing facility, with florescent lighting, bad shadows, etc. No extra lighting available.

I usually shoot long (5 - 15 sec) @ f/22 [however, after advice here will try f/8 or f/11) w tripod.

I think the HDR would give it the depth and pop that might wow the client.

Thoughts? Techniques?

ziggy53

John_Walsh wrote: »

... No extra lighting available.

...

?

If this is a paying job it is your responsibility to show up with all of the equipment needed to satisfy the needs of the shoot and to meet the client's requirements. This would include additional lighting as required.

If this is a typical manufacturing plant lighting will be photographically poor and unmatched. You may have a mixture of fluorescent and high-pressure sodium or mercury vapor. You may also have daylight from windows and some important areas without any native lighting at all.

You and the client should have communicated sufficiently so that you have a clear understanding of what the client wants. If you want to "wow the client" that would come from interesting perspectives and your control of lighting. Accepting available light will likely give you much, much less than what you and the client wants.

HDR tends to accentuate any grain and noise so if you intend to use HDR process I would recommend the lowest ISO possible and do not underexpose. Tone blending, both manual and software automated/assisted, may be a better solution to "some" of your issues.

If you have the opportunity to visit the site before the formal shoot you might take some snaps just so you can review the typical lighting and note the problems you will encounter during the actual shoot. This will save you a lot of time later on.

John_Walsh

Thank you for your response.

Yes, I have a flash and softbox that I'll bring. Even so, it's an active facility and getting the right shot can be a challenge with reflections and color bleed. And yes, have shot / worked with this client for the past 10 years.

I was playing the angle that HDR can "do a lot with less that perfect lighting". What do you think? Does HDR have a place in product photography?

ziggy53

John_Walsh wrote: »

... Yes, I have a flash and softbox that I'll bring. Even so, it's an active facility and getting the right shot can be a challenge with reflections and color bleed. And yes, have shot / worked with this client for the past 10 years. ...

Work your lighting to accentuate the important details. Bring in extra lights as you can and as the scene and scene requirements dictate. Take control of the lighting and don't try to just accommodate the status quo ambient light.

Yes, it's difficult and challenging. It's also very rewarding when you get it right.

John_Walsh wrote: »

... I was playing the angle that HDR can "do a lot with less that perfect lighting". What do you think? Does HDR have a place in product photography?

It does sound like you want to use "tone blending" more than what most people think of as HDR.

A very nice software that I played with, but never used on anything serious, is Oloneo PhotoEngine:

http://www.oloneo.com/

Take a look at their HDR ReLight function:

http://www.youtube.com/watch?v=YnKms4wW8O8

In your application, using the lights that you have to strategically illuminate areas, zones and subjects, you might be able to take the multiple exposures and combine them a little more easily using the Oleono software.

Moving subject matter, personnel and machinery, is going to complicate things dramatically.

Ultimately you may be better off using traditional Photoshop masking and blending techniques.

ghinson

Looking at your response, I looked into Oloneo. Some exciting looking stuff in their demo. But no Mac version! And reading their user forums on flickr, no apparent plans for a Mac version! These days, that just seems crazy.

Have you used it or been able to compare it to Photomatix Pro?

ziggy53

ghinson wrote: »

Looking at your response, I looked into Oloneo. Some exciting looking stuff in their demo. But no Mac version! And reading their user forums on flickr, no apparent plans for a Mac version! These days, that just seems crazy.

Have you used it or been able to compare it to Photomatix Pro?

If you're asking me, I tested a beta version of the Oleono software around a year ago. It was interesting but did not meet my needs.

I had previously purchased (2-3 years ago) Dynamic-Photo HDR (DPHDR). I like it lots better than Photomatix for my applications, which are often 1 image "fake" HDR simulations.

This is partly using DPHDR against a very dull scene, photographed with a P&S on a very cloudy day:



If I were doing work that needed to mix multiple exposures and mixed lighting zones, and if I wanted more control of how the lighting zones mixed together, I would be seriously considering the Oleono software.