In the world of VR creation (all of photographic creation actually), one of the current hottest topics is HDR imaging...that is, High Dynamic Range imaging.
In a nutshell, the challenge is how to realistically reproduce an impossibly high contrast image without losing shadow and hilite detail, be it destined for print, screen or web.

As I stated in my last article (VRMag Issue #28, Advanced Panoramic Stitching - A Reasoned Approach), HDR imaging is not a new thing...it's just that now we've got a name for it. Ansel Adams' Zone System can be viewed as one of the earliest methods of HDR imaging.

A greater challenge for the toolmakers is the fact that HDR imaging is truly an advanced user concept in it's purest form, yet the market is demanding a form that makes it easy for the masses to pick up and use effortlessly. Here's just one example of what I mean by that ...

Let's say you have an HDR tool that enables you to convert an extremely high contrast image into a form that reproduces nicely on your web site at 72dpi, and a gamma of 1.8 in an sRGB color space. But this is a key image in your whole advertising campaign, so you also have to reproduce this same image hi-res in magazine advertising, then as a hi-res RGB print, a wide body injet CMYK print, television use, then direct to digital print ads, then coupons, and so on. Each of these media has different needs as to contrast, colorspace, density, etc, yet they all have to present the same look and feel for continuity purposes or your customers will be put off.

How do you do all of that with one file?...two choices:

1: TONEMAPPING the HDR file.
To repeat what I stated a moment ago, HDR imaging is an advanced concept. What the toolmakers are struggling with is that yes, they can truly pack the entire dynamic range of a high contrast image into one image file, but what's not coming thru clearly to the masses is that this particular image file is not usable as is. Think of it this way - the actual HDR image is a "Master" image file. In order to make it usable for a given medium, you need to extract a subset of it...that's where the term "tonemapping" comes in. The tonemapped image is not the full HDR image, but it is the image you'll need for your communications piece. So, from one master HDR image you can extract all the tonemapped images you may need for your various communications pieces (and it could be that one tonemapped image may serve multiple needs, but probably not all needs). So you file away the master HDR file and pull it out as needed to generate the appropriate tonemapped images.

2: IMPORTING the Full HDR Image.
More and more tools are becoming capable of importing full HDR images and incorporating them into their workflow. Current HDR file formats are OpenEXR (.exr) and HDR Radiance (.hdr). For example, in our own world of 360º VR images, Stitcher 5.6 Unlimited supports importing HDR files created in other software and uses them for stitching high contrast images. In a future version, Stitcher may enable creating HDR images within it's workflow, but for now, it supports importing and stitching HDR images created elsewhere (Photoshop, PhotoMatix or another HDR creation programs of your choice). Note: PTGui Pro 7.5 currently has the capability of creating and stitching HDR images within its workflow.

(For more information, Google Using OpenEXR images, or Importing HDR Images, or a like search and you'll find much more on the topic of high dynamic range file formats and their use).

All the toolmakers realize the complexity involved, and struggle with the issue of balancing "full-featured" against "user-friendly" when designing their HDR tools. Some of their customers understand the complexity as well, and want full featured software where they can tweak the math to their hearts content, and they understand what's going on under the hood. But, the money is in the masses...a software that does a good job and is easy to use by those who don't understand the math is like the holy grail of HDR.

Against this background, you, the consumer, are offered choices by the toolmakers.

THE MATH is THE MATH is THE MATH

None of the toolmakers have a lock on the math required to process HDR images. It's like physics...nobody is exempt from gravity...same with the math used in HDR image processing.

That means all the toolmakers have an equal shot at creating just the right product. It's about interface and usability. There are actually many, many HDR products out there already, from PhotoMatix, one of the earliest, to the Merge to HDR tool in Photoshop, to the HDR capability built into some stitching programs such as PT Gui Pro and hugin, to the program I'm reviewing today - HYDRA, with many, many others out there waiting for you to find them. Here's a web page that gives a bit of an overview of HDR software choices:

http://wiki.panotools.org/HDR_Software_overview

(Google, "HDR Software" and you'll find plenty more research material)

CREACEED's HYDRA

Up until now, this article was for everybody...hopefully you've already learned something new about HDR imaging, or found some directions for your research.

HYDRA however, is Mac only. Here is how Creaceed puts it on the History section of their web site:

Creaceed is a joint effort conducted by passionate people. Our goal is to provide creative tools that are intuitive and easy to use to Mac users. We want to give our users a unique way of using their Mac, in terms of user experience, interactivity and features, that can't be found on other platforms. To these great tools and platform, we bring our experience in signal and image processing to attain new creative goals.
HYDRA is one of six tools currently on the Creaceed Products Page.

Installing OSX 10.5 Leopard

When considering Hydra, one of the first things you'll find is that it requires Leopard (OSX 10.5) in order to use it. If you're not already using Leopard, you'll have to make the switch. If that sounds like an inconvenience, let me counter that it's nice to have some products written for Leopard from the ground up. I'm sure Windows folks have the same feeling about products written or optimized for Vista.

One comment on the upgrade to Leopard. It's a significant upgrade and a significant process...not quite as straightforward as many previous Mac upgrades. Lots of stern admonitions about backing everything up, etc...more than usual. As it turns out, I was required to reformat my drive before installing Leopard...didn't have a choice.

Before I upgraded, I ran DiskWarrior on my MacPro laptop running OSX 10.4.11 to make sure all the minutia was in proper order. Then I cloned my drive to a 160GB external firewire hard drive using SuperDuper! from Shirt-Pocket.com. I personally trust Diskwarrior and SuperDuper!, and they gave me great confidence as I reformatted my laptop, and made the switch in operating systems.

I also have faith that DiskWarrior put my drive into the best condition prior to the switch. I can't imperically support that, but I can say that since switching to Leopard, I haven't suffered any ill effects. No lost files, no printer problems, nothing. I credit DiskWarrior and SuperDuper! for helping me make a successful transition to Leopard. That's simply a personal observation (and I bought my copies, wasn't provided any incentive to endorse them...they don't even know who I am).

OK, finally...on to HYDRA -

I stated above that what will differentiate one HDR tool from another is interface and usability, i.e. - repeatable performance and ease of use:

• how much effort does it take to learn and use?
• does it perform up to your expectations?
• is it's performance predictable and repeatable?
• how's the cost to value ratio?

Here are a few quick first impressions to get started:

• installation and registration were fast and easy,
• the user's guide is brief yet complete, 17 pages total if printed, and well illustrated, easy to skim and get started,
• I had my first successful output within ten minutes.
• three steps in the workflow

With that as groundwork, let me briefly outline the workflow using three images I shot recently for the purposes of this test. The source images were shot handheld to test HYDRA's claims that a tripod is not required.

Selecting "Start Using HYDRA" brings up a new document and a HYDRA info window,

Dragging a series of three bracketed images into the new document brings up the following screen:

The info panel first displays the "Photos" page looking much like the layers palate in Photoshop. You can see all the images you've loaded (up to four) and examine them one at a time if you'd like. You can add or delete files right from the photos page in the info panel.

The second page in the info panel is the "Matching" page.

The default screen displays the density and positioning of matching points. From the info panels "Point Density" slider, clicking "Align Images Automatically" enables you to increase the number of points,

and by using the arrow key, the "+" key and the "Adjust" button, you can change the position of points, add new points manually in select positions, and examine the alignment of points within your bracketed images.

The final page in the info panel is the "Blending" page.

Tools provided within the blending enable a serious level of control over the final blended image.

Adjust the histogram and the Smoothness & Blending sliders until you are pleased with the preview.

Then select Jpeg or Tiff and hit the "Render HDR" button.

The rendered image will display onscreen along with the existing HYDRA workspace & info panel windows.

Finally, you are prompted to "Save to Desktop" or "Export to iPhoto".

That's it! I could have gone into a little more detail, but not much really...it's a pretty abbreviated process compared to some of the more complex HDR softwares on the market.

MY take on HYDRA -

PRO's

In terms of balancing ease of use with full featured, I think Creaceed has done a good job. Hydra is very easy to use, yet it provides a good level of control over the results. I believe this is a product you should put on your list to consider, if you're in the market for an HDR product, you're a Mac user, and you already know you don't want the more complex level of HDR products.

The resulting images are clean. I'm always leary when buying a software that rates high on ease of use or operates mainly on presets. I'm concerned about these products increasing noise or other artifacts in the images, HYDRA doesn't seem to have that problem.

I have a reputation for being good with available light photography, and I used HYDRA on an active project recently while evaluating it. I was photographing at the 2008 CES tradeshow (Consumer Electronics Show) in Las Vegas where the subject matter is high contrast by definition. I found myself combining HDR technique with stitching in order to enable certain shots. I ended up shooting every shot on a tripod at three exposures...normal as well as plus and minus two stops. I decided I'd try processing them in HYDRA, knowing I had other choices as back-up if HYDRA didn't give me what I needed. I ended up staying with HYDRA...I liked what it gave me and how quickly I was able to learn it. I particularly liked the degree of control the blending tools provided, and I liked that I could fix a mis-match by adding points manually in selected areas of the photo, and by using the "adjust points" mechanism. Here are a few images from that high contrast shoot at CES.
The following shots were done for AV Images, a company that specializes in hi-tech lighting, displays and audio in tradeshow and exhibition environments.

The Entryway shot captures the dramatic entryway to a hi-tech demonstration room. It used a technique dubbed "Stealth". It's essentially a "beaded curtain" where the individual beads are programmable and addressable. As a display mechanism, you can program graphics onto these "Stealth Curtains". The curtain was less than twelve feet from the entrance door, and it was fourteen feet high. There was no way traditional lensing would capture it. Pressed against the back wall, I set the camera position at seven feet (mid-way up and square to the stealth curtain), and I shot four overlapping verticals using a Kodak ProSLR full frame camera with a Nikon 20mm rectilinear lens, mounted on a Kaidan Pro VR rig. By stitching these four overlapping verticals, I was able to create a "virtual lens". I set the camera to manual mode, enabled bracketing, and shot a full bracket in each of the four camera positions. I used no lighting gear. The illuminated stealth curtain was not only the subject matter of the shot, but also the only light source.

I used HYDRA for the HDR work, Stitcher 5.6 Unlimited DS to stitch the four shots, and rendered the resulting stitched image as a "snapshot" image. Finally, I used Photoshop CS3 for finishing work. The plasma screens are purely photographic, but shot in place and retouched in. I used a single strobe with an umbrella and available light time exposure to light each plasma screen. The Cisco logos on the plasmas are as photographed.

The two shots below are also stitched partial panoramas with the same basic workflow.

Using HDR technique for this series of shots enabled me to capture dramatic imagery quickly (i.e., no lighting gear) while maintaining full control over the tonal range of the resulting images. I was able to exercise full control of my imagery in a high contrast environment without driving my clients nuts with a lengthy and intrusive photo shoot.

CONs
In my estimation, most of the cons to HYDRA are associated with the fact that it's a version 1.0 software. It's missing some things. I'm guessing there might have been a bit of a rush getting it released in time for MacWorld two months ago. It's up to you and me now to tell them what we want added.

For example, there is no option in the v1.0 software to save settings, there is no option in the v1.0 software to batch process, and there is no option in the v1.0 software to "save as" HDR or Save as OpenEXR. Those are all very doable, and when asked what's coming in the future, Raphael Sebbe, Creaceed product developer responded, "... when we have tone-mapping and EXR, we should be able to handle batch processing much more easily." He also said they'd be adding support for RAW files soon, an provided the following list of the main features to be upgraded or added: raw input, tone mapping, aperture integration, localizations, individual warp export, better fullscreen, and update the UI...all of course, as a free upgrade to registered users. See more about HYDRA at http://www.creaceed.com/hydra/ where HYDRA can currently be purchased for $59.95 USD, 41.16 EUR, or one of twelve other currencies.

POSTSCRIPT
Just after I finished this article I had the opportunity to photograph one room of a nearby "bed 'n breakfast". This demo panorama would be included in a proposal to create a 360º VR tour of the entire hotel. Because it was a demo pan I figured I'd do it available light so it would go fast, yet would have reasonable quality. I showed up with a tripod and a camera . . . zero lighting gear, not even an on-camera flash.

The sun streaming through the window in the poster view was direct and therefore intense, and the area to the right of that window was in deep shadow. It was as severe a lighting ratio as it gets. By using HYDRA in conjunction with Photoshop, I was able to create this shot 100% by available light . . . no lighting gear whatsoever! (I used Stitcher Unlimited 5.6 DS to stitch it, and Cubic Converter to finish it).

Note - HDR imaging is an advanced user concept. HYDRA is a tool, just as Photoshop is a tool. The results you get with either (and the two in tandem) will be proportional to your level of experience in creating professional imagery.

click here to view bed 'n breakfast panorama

You can follow up with questions or address your comments to the author: pat at stclairphoto-imaging.com, and see more of his work at: www.stclairphoto-imaging.com

Pat St. Clair has a bachelor's degree in marketing from Miami University (O), 1971, and a bachelor's degree in professional photography from the Rochester Institute of Technology, 1979; he has been photographing commercially since 1978. St. Clair serves a corporate clientele that includes agencies of all sizes as well as direct corporate clients such as Eastman Kodak Company, Palm, Xerox, Hewlett-Packard, The Smithsonian National Air & Space Museum, 3Com, DaimlerChrysler, ExxonMobil, Microwave Data Systems and more. He was an early adopter of digital photography as well as interactive photography. He worked as a consulting photographer with Eastman Kodak Company on digital capture projects and digital image quality issues for fifteen years as they brought their professional digital photography technology to market. He has worked with QuickTime VR since 1994, is a charter member of the IQTVRA (now the IVRPA), and was a speaker at the first four International VR Summits in Boulder, CO, Washington, DC, Sedona, AZ and Savannah, GA.

Previous Articles by Pat St. Clair:
ADVANCED PANORAMIC STITCHING - A REASONED APPROACH
VR TOOLS YOU CAN USE - GREENSCREEN
VR TOOLS YOU CAN USE - PARTIAL PANS MADE EASY
MIRROR IMAGE - REFLECTIONS ON SINGLE SHOT VR BY PAT ST. CLAIR
VIEWPOINT, THE NEW KODAK PROFESSIONAL PRO 14n DIGITAL CAMERA
VR TOOLS YOU CAN USE: QUICKTIME VR OBJECT MOVIES
2005 SUMMIT IN SAVANNAH
TOP THREE PHOTOGRAPHY QUESTIONS ANSWERED
VR PHOTOGRAPHY TIPS AND TRICKS