I've recently learned a great trick for getting natural HDR results for virtual tours without a lot of extra work.

If you have a camera that generates RAW files, your camera is already capturing much more exposure information than a typical JPEG can handle. Most RAW files store 12 bits per pixel, and some newer ones are 14-bit. A 12-bit file has 16x more information than a JPEG, and a14-bit file has 64x more information.

Coupled with good HDR software, a single RAW file can be converted into multiple "simulated" exposures and you can output a nice, natural-looking tonemapped picture from a single shot.

While it's true that you will get even more dynamic range from multiple exposures, this only really matters if the light range of the scene is extreme. There are two other big advantages of the single-RAW workflow: since it's only one exposure, you never have issues with ghosting due to wind, clouds, or other moving objects between shots. Secondly, the workflow is very simple since it's just one shot!

Here's a sample I worked on tonight:

Original



Photomatix



QTPFSGUI



The first example was done with Photomatix software, which is available for Mac and Windows and is reasonably priced at $99. There is also an open-source application that can do the same thing, called QTPFSGUI. The second example was done with QTFSPGui.

In Photomatix, to get started you just "Open" the RAW file and wait. It will generate the "pseudo-HDR" file and allow you to apply tonemapping. Photomatix also has a nice noise-reduction filter which is very useful for shadow details on some camera.

In QTPFSGUI, you just do "New hdr,"choose the RAW file, and hit "Next" then "Finish." Click "Tonemap the HDR" and play with settings as you like. There are a bunch of different tonemapping algorithms listed by their creators. The "Reinhard '05" and "Mantiuk" options seemed to do a nice job with the samples I tried. All of the algorithms have adjustments.

Photomatix has a Batch Processing mode, although I am not sure if it can work with this workflow.

All in all, this process offers a very low-cost, fast way to improve your images that I think is perfect for images bound for TourBuzz!

Enjoy,
Alan

Views: 997

Comment by Hamish Tear on February 19, 2009 at 12:17pm
Hey Alan,

Some photography forums pooh-pooh this idea as there is a loss of detail over taking, say, three or five bracketed images of the same scene. But life is full of compromises and it all depends on the level of what you want out of it - and how much your time is worth. The workflow may, or may not, be simpler / quicker in this method.

There is big value in eliminating alignment problems on each set (no tripod shake or movement) - and it saves battery and storage.

Taking five bracketed images takes no more time than creating four copies of a single image, then opening them in the RAW converter and exposure-adjusting the copies to +1,2 and -1,2 values to support your HDR requirements..

My workflow, (from either camera or generated HDR images) which is long, then includes adjustments to each image - especially Recovery, fill light and blacks. But then I'm dealing with five stops of difference in window shots with incredibly bright and snowy exteriors.

Am I right about your workflow above? - Please detail a litle more about what you do with the single image before opening in P'Matix.

Batch processing works fine in P'Matix. ANother way is to convert the raw files to 16-bit Tiffs and then put the whole package into PTGui and enable the HDR - one less piece of software to deal with, although, again, there can be a compromise on the final outcome.

Maybe this workflow need a little further detail:
Comment by Alan Pinstein on February 19, 2009 at 2:53pm
Actually, this part is wrong that you say:

"Taking five bracketed images takes no more time than creating four copies of a single image, then opening them in the RAW converter and exposure-adjusting the copies to +1,2 and -1,2 values to support your HDR requirements.."

The nice thing about the single-RAW HDR workflow is that the SOFTWARE does all of this for you. All you have to do is OPEN the RAW, then TONEMAP. That's it!

There's no question it's not as good as using 3 or 5 "truly" bracketed images in terms of real dynamic range, but there's also no question that it offers a way to *improve* the dynamic range of a single JPEG. The RAW has more dynamic range than a JPEG, and a "simple" conversion of RAW to JPEG doesn't make use of this extra exposure info.

I think that the single-RAW HDR workflow is a great improvement with very little increase in time, especially for those that are already opening and tweaking every single image anyway. And it's particularly useful if it's windy or there is motion in the scene, which is very common with outdoor shots of real estate.

Alan
Comment by Marcie Heitzmann on February 21, 2009 at 1:42pm
Hi Alan,
Thanks for the tip on RAW files. I did not realize I could open a RAW file directly in Photomatix. I thought I had to convert to jpg first. Anyway, I tried it and it looks pretty good, but, I don't think as good as taking 3 separate exposures. However it is a time saver and I don't think clients would notice the difference. And it does help in windy conditions. Also, note, I came pretty close in the HDR look by just playing around with the Camera RAW converter in Photoshop. Many ways to skin this cat.


Marcie Heitzmann
Comment by Alan Pinstein on February 21, 2009 at 1:57pm
There are definitely infinite ways to improve picture quality in post-processing! I think think workflow makes sense when you want better quality without a lot of extra hassle. I would imagine that in the future this will get even easier. I have been thinking about making some custom batch scripts that would do all of this automatically. Maybe even just present you with 5-6 "best guesses" for an improvement and you just pick the one you want.

QTFPSGUI comes pretty close to that now as you can quickly create a bunch of previews based on different algorithms and just save the one you want.

Alan
Comment by Michael Basch on February 21, 2009 at 5:30pm
Hey Alan
Just a quick one- sounds like everyone is using HDR technology for their still shots. Are they also using HDR for their stitched views?
Comment by Alan Pinstein on February 21, 2009 at 6:49pm
As far as using it for stitched views, it gets tricky. The ideal way to do it is to have the stitcher support HDR directly, like PTGui does. The latest version of PTGui, 8.1 (just released!) directly supports RAW file import now, and I think it might allow this technique directly in the stitcher! Sadly my camera doesn't produce RAW files so I can't test it out right now, but it sounds promising.

Also, I just found a great HDR-from-single-RAW group on Flickr that has a photo pool and discussion group.

Alan
Comment by Linda Sabiston on February 21, 2009 at 8:41pm
I think using HDR for Real Estate has to be done with a lot of finesse. It's really easy to go over-the-top with it. I believe it's important to keep in mind that we as RE photographers are showing the interiors as we have seen them ourselves. In real life there are shadows and dark areas. In HDR there isn't. I have seen some outstanding HDR, you wouldn't even know. But sometimes the colours get that nuclear look to them, too vibrant, lighting takes on an orange glow, white ceilings take on a smoke stained appearance and often the image has an all over metalic look to it.
Don't get me wrong, I encourage everyone to try it... but ask yourselves, if that's really how the room looked? The images you create are going to be the prospective buyers first impression. Are they going to see the same thing once they go for a viewing? How will they react?

Linda
Comment by Alan Pinstein on February 21, 2009 at 9:11pm
Great point, Linda. I always say "try to make it look like you're standing in the room". Shadows in pictures without HDR look a lot "darker and worse" than in real life, because your eyes adjust as you look around. I think if people try to make the output "like being there" you can't go wrong.

In fact I just posted a web page about these techniques with some links to a bunch of real estate HDRs if people want to browse examples.

Alan
Comment by Michael Basch on February 22, 2009 at 10:56am
I am in total agreement. Many of the HDR photos I've seen are works of art. Pieces of perfection but very surreal. The real talent as an RE photographer is to capture the true feeling of the room.
Comment by Chris Thomas on February 22, 2009 at 2:03pm
Just follow David Palermo and Dan Achatz and some of my new favorites Raif Fluker and Alejandro Villanueva, on the Flickr PFRE group and you'll see some excellent HDR work. David G Fisher has some excellent shots with the vivid colors and deep contrast that I really like.

Another take on this subject is the Hand Blending technique where instead of relying on the HDR/Enfuse software to predict how to blend, you manually blend them in Photoshop using layer masks, layer opacity adjustments, and every other way you can think of. Jeri Koegel does excellent hand blending as well as Dan Achatz and David Palermo. It is the slowest way to go but on the commercial shoots and highest end luxury homes it is excellent.

As far as working from a single Raw, I would only use it in a pinch where a 3-5 shot burst is not possible. Even though Raw has a higher dynamic range than a Jpg, it's only because a tone curve was not applied to add contrast yet. If you use the Raw converter that comes with your camera, using the standard profiles your Raws will look very similar and only slightly better than the jpg version from your camera. You're sensor can only capture so much dynamic range, even in Raw. Check out DXOmark.com to see the dynamic range of different camera's to see quantifiable comparisons. One good example was Dan Achatz's 50D that he returned because it had such lower dynamic range than the 40D even when shooting raw on the 50D compared to the 40D's Jpgs.


Linda is absolutely right on the "fine line" of HDR. I've been very hit or miss with mine, and find that in almost all cases a little bit of added light always helps. The new "Hybrid-HDR" technique that is becoming popular seems to me to be the best way to get both a shorter on-site time and a wider dynamic range with deeper richer colors. I'm not a fan of the Blasted room look that some of the PFRE guys use, but it does definitely create very crisp details that a no-flash HDR seems to lose.

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