Hi All - For budding and experienced HDR worshippers:

Picturenaut Notes

Some HDR software has been sitting in my programs files for some time, without my having properly looked at it. This is Picturenaut, available for free download from [URL="http://www.hdrlabs.com/picturenaut/"]/URL]. The current stable version is 2.12, but there is a beta version, 2.81, with many updates available from the website forum.

The developers, Marc Mehl and Christian Bloch, are from Germany and the software is part of a larger suite for image processing from http://www.hdrlabs.com/. The history of what the developers call "the new kid on the block" appears to be from Paul Debevec's progran HDRSoft and Picturenaut contains, via plugins, many of the original algorithms for hdr creation and tone mapping. Even my old favourite from Qtpfsgui, Drago, is there and one of the main tone-mapping algorithms is from Reinhard.

The software seems to me to be particularly easy to use, but that might be simply by comparison with "you-know-who". Powering up leads to a standard type of menu that allows loading of images to create a new HDR map or to open a previously created one. In the current version, only TIFF and JPGs can be melded, but the beta version, 2.81, claims to be able to handle RAW files. The "Generate HDRI" screen has some powerful options:exposure correction, automatic image alignment, colour balancing, and various weighting factors. You can also change the camera response curve and load your own. How easy is this compared to Qtpfsgui?

On my quad core machine, a 5 image HDR map takes about 15 seconds to compute at the 16-bit level. This processing speed is fast and is a feature in Picturenaut, the software having been engineered to accommodate multiprocessors. You can save the map as an hdr file and, at the same time, a camera response file is saved as a .crv file. Once created, these crv files can be loaded earlier, and possibly modified (I'm looking into that.)

There are two major tone-mapping algorithms available from the Image menu item: adaptive logarithmic and photorecptor physiology (this one from the Reinhard school). Picking either gives an interactive screen with real-time updating of the tone-mapped image. A histogram is also displayed and updated realtime (Joy of Joys!!). I'm not going to describe the slider controls as they appear to be intuitively easy. I suppose the key idea is to enhance the histogram so that it takes up the largest range with the most detail.

Note also in the Tone-mapping screen that there are various options for gamma adjustment and output format. The resulting tone-mapped image can be saved in the usual way.

The final point of interest is that at the bottom of the screen is a processing information window. You can see what stages the calculations have reached. One aspect of the processing is the creation of a temporary file in your Documents and Settings file structure. You may have to create a TEMP directory to accommodate this file.

Overall, this is a piece of software that is well worth looking at if you want to explore HDR imaging.