The HDRI Handbook: High Dynamic Range Imaging for Photographers and CG Artists [Englisch] [Taschenbuch]

I have been learning about HDRI primarily from Uwe Steinmueller's generously helpful articles on his site outbackphoto.com, and from the Photomatix email list. Seeing that Steinmueller is a contributor to The HDRI Handbook, I expected it to be more of the same.

In the event, it has been an epiphany. I had not appreciated that HDRI is a doorway into truly archival imaging, for today's imaging technology *and* for imaging tools and output devices not yet invented. I had completely missed the point made on page 132 of The HDRI Handbook:

"Most photographers will tell you that the next step [after having merged bracketed exposures into an HDR image] is tone mapping because an HDR image doesn't fit the limited range of our ..." output devices. "This is missing the whole point."

"*Don't throw it all away yet!* There is nothing special about an HDR image. It's all just pixels waiting to be messed with, but better pixels that are much more forgiving when we apply extreme edits. Imagine the HDR image as raw clay that we can form into whatever we want. Why would you burn that raw clay into a hard block now just so you can destructively chisel the final form out of it? Wouldn't it make much more sense to massage the clay into a good model first? [Apply non-destructive edits to the HDR image itself!] And then put it in the oven the fix that form [tone map into an LDR image], and sand and polish [fine-tune with LDR editing tools] afterwards?

"To speak in more photographic terms: Here we have an image that exceeds the tonal range and qualities of a RAW image. Wouldn't it be great to keep it like that for as long as possible? Well, you can! That's what true HDR workflow is all about.

Christian Bloch then describes a 32-bit workflow to do just this. An HDR LDR workflow can be broken down into three parts. Bloch describes and compares the tools available for each part, and examples of these are provided on the DVD that comes with the book.

First, combine bracketed exposures to create an HDR image. Block focuses on using Photoshop or Photomatix for this step.

Second, use Photoshop to make basic adjustments to the HDR image. These are: cleanup with the Clone Stamp, white balancing (done in two steps, differently than in LDR images), frame/perspective correction (using Free Transform), sharpening (using the HDR exposure changes to visually quantify proper sharpening), and color correction. None of these need to be done to the HDR image, but Block discusses the advantages of doing so, *before* converting to LDR.

Third, tone map the HDR image into an LDR image. For me, this is the core, creative part of HDR imaging in photography. Bloch distinguishes two perspectives.

One perspective is to have "the final image appear as natural as possible, ... an image that looks like it was shot with an ordinary camera but incorporates more dynamic range than a camera could actually handle." (page 168).

The other perspective is to create an "painterly" interpretation, as illustrated by the many example images seen on the web.

Bloch illustrates tone mapping of four different HDR images, using the four methods in Photoshop (Exposure & Gamma, Highlight Compression, Equalize Histogram, and Local Adaptation), Photomatix Details Enhance, FDR Tools Compressor, and Artizen HDR Fattal.

The tone mapping that seems to offer the most precise control is Photoshop's "flagship tone mapper" (page 155): Local Adaptation. The mapping is crafted by adjusting a toning curve to set black and white points, and to control local and global contrast. Bloch's detailed examples show precisely how to work with this approach. I show an example of this in the Digital Dgrin Photography Forum post

<http://dgrin.com/showpost.php?p=718903&postcount=8>

Uwe and Bettina Steinmueller describe (pages 172--182) how they have used Photomatix to produce their stunning images of interiors of abandoned buildings.

Also, there is a very helpful, detailed (page 183--211) tutorial by Dieter Bethke, of how he used Photomatix to create three "natural" and two "painterly" images. It is a great resource for getting to know how to use Photomatix and an encouraging illustration of the capability of HDR imaging as a photographic tool.

There is much more in The HDRI Handbook but this is what I have gleaned so far. The HDRI Handbook has turned out to be a wonderful, measured, detailed, and accessible guide to what an HDR > LDR photographic workflow has to offer.

The principle was so obvious to me, and yet as soon I finished the study of this book, I realized just how limited my prior knowledge was. Apparently I did not knew about existing image standards, tools and about a fundamental importance of HDR (high dynamic range) imaging for digital photography as a superior way of preserving images.

Foreword is by one of the top gurus in the discipline and author of several graphical file formats, Greg Ward.

Author starts with explaining the basic concepts of dynamic range, EV (exposure value) and specifics of human perception of light and shape. This sounds like a platitude, but in fact the chapter is very educational and to the point. Reader can quickly understand the limitation of the contemporary digital imaging based on integer numbers. I had no idea that HDR tools and files use in fact floating point numbers, utilize exponents to cover the vast dynamic range, while occupying still the same number of bits per pixel.

In chapter 2 author goes through the numerous file formats invented to hold graphical information, beginning with Kodak's Cineon, Portable Float Map, Float Tiff, Radiance, LogLuv, Open EXR (devised by Florian Kainz at Industrial Light and Magic,) High Dynamic Range Jpeg, Fjpeg, and several more. I was not aware of the most of them. Tabular summary at the end provide a perfect and compact summary.

He summarizes than properties of the diverse HDRI tools, of which I knew of Photomatix, but the rest was widely unknown to me. One group of programs contain generic image viewers with HDR capability, like HDRView, exrdisplay, JahPlayer. Even Irfanview can apparently interpret two HDR formats: radiance and TIFF LogLuv. Later Bloch compares features of HDR file generators and tone mappers: HDRshop, Picturenaut, PhotoSphere, Photomatix and FDRTools. This is the most comprehensive enumeration of HDR software which I saw so far. Of course, he also talks about full image editors and compares their features to Photoshop CS.

Chapter 3 is devoted to capturing HDR images. Bloch explains limitation of contemporary CCD and CMOS sensors, talks about future prospects. He explains how to use bracketing in ordinary digital cameras to gain series of images covering the wide dynamic range. Foremost he reminds to use the same aperture to preserve identical depth of field in each shot. Sounds so obvious, and yet before I red this book, I made series of images violating this principle. Expectedly I gained poor results, which I than attributed to an "immature HDR software." If fact, I was not ready. Bloch follows with a description of a series of workflows using dedicated tools, like HDRshop, Photomatix, Picturenaut, and compares them to a fully manual process in Photoshop. Very educational.

Next chapter describes tone mapping: Once the HDR image is in place, its vast dynamic range must be mapped into the Low Dynamic Range (LDR) of the display, screen or paper alike. The process has many variables and an element of artistic freedom. Here again Bloch compares several automatic tools with a manual process in Photoshop. Some of the example images are simply stunning. The chapter has several sections written by other photographers presenting their selected HDR images.

As a bonus follows a chapter about shooting of HDR panoramas, a combination of two dimensional series of images for each part of the scene, and for each part of the dynamic range. Fascinating are all the gadgets and contraptions being used to generate the surreal projections and circular panoramas.

To sum up Bloch speaks about trick photography combined with CGI (Computer Graphics Images.) This is of course just a short introduction in context of HDR, and yet very informative.

For me this is one of most educational books in photography which I ever read, and do I press the shutter button for over 30 years. Do yourself a favor: grab it and read it and foremost: Experiment with HDR!

I had seen the book announced months ago and was probably one of the first customers to order a copy. It took me about two weeks to read it from cover to cover and check out some of the resources on the disc. This is an amazing source of information! I am a photographer and I was intrigued by some of the HDR-Photography I had seen posted on the web (by Dan Burkholder and others). I started experimenting with some of the tools like Photomatix and Photoshop but these were fairly random experiments and I did not get consistent results. After reading Christian Bloch's HDRI Handbook, I think I understand this technique and the underlying concepts and I feel I can embark on a new and better planned trip into the field of High Dynamic Range Photography.
Luckily, I can use many of the bracketed shots that I still have -- and I already started to reprocess some of them with software that was included on the disc. I was blown away by the first results. HDRI is fun and I expect to spend many more nights over the next few weeks to create HDRIs. I am just starting, but this book is, in my opinion, a must have for any serious and forward-thinking photographer.
I highly recommend this book.