HDRi software has been getting a bad press recently, perhaps due to some of the very extreme “surrealistic” images that are readily found on the web and in particular on Flickr. But it doesn’t have to be that way. The more subtle combinations of multiple exposures of a scene can produce a beautiful and more realistic result. In my quest for the best in HDRi software, I’ve been taking a look at Picturenaut.
Picturenaut is open source software being developed by HDRlabs. When you download the software, which is completely free (though a donation is welcome), there is a pdf file that you can download to show how to install it and basics of use. This proved to be very well written and easy to follow.
Using the same tree, photographed in 5 shots with 1 exposure between each, I made a comparison between PhotomatixPro and Picturenaut conversions. Picturenaut aligned and combined the images a little faster than Photomatix, though on just one testing I think it would be unfair to say that this would always be the case. The Picturenaut controls were easy to use and the large preview enabled accurate control of the tone mapping. There are two global tone mapping interfaces, Photoreceptor Physiology, which is said to protect underlying colours beneath highlights, and Adaptive Logarithmic, which creates a smooth logathithmic compression. These are to be combined in a future version, but at the moment you have to choose one or the other. I used Photoreceptor Physiology. Once you have adjusted any of the sliders, the main image is quickly updated with the changes and I found it (on this image) much easier to achieve the result I was looking for than with Photomatix.
Reading around the subject tells me that the global tone mapping in Picturenaut does not carry with it the risk of severe haloes and surrealistic blends, which you can get with local tone mappers like Photomatix. So, the resulting blended image is more realistic. For those people who like the surrealistic blends of Photomatix, I would suggest that you won’t find those in Picturenaut. However, it is rumoured that, for those individuals wanting a more extreme blend of images, Picturenaut will, in fact be introducing a local tone mapping feature in a forthcoming version.
I imported the resulting tiff file into PhotoShop, where I carried out the same “finishing” to the image as I had with the Photomatix image, except for the sheep on the horizon, which I left in the Picturenaut version. The results are very close, see below.
The Photomatix sky is very slightly darker and more saturated. Cloud detail and contrast is also very slightly better in the Photomatix version. Fine detail of the branches and tree trunk is very slightly better in the Picturenaut image. Both exhibit a good crisp blend of the images (which were taken on a tripod but in strong wind).
In addition to HDRi production, Picturenaut also features “automatic image alignment, exposure correction, colour balancing, noise level compensation, automatic computation of the camera curve from the source images.” Additionally it offers 7 different interpolation options for resizing HDRs. There are a number of plugins available for Picturenaut, which I have not yet tried, including HDRShop plugins and a collection by Francesco Banterle.
This is a very first impression and I cannot say, with fairness, which software is better. I need to make some comparisons with more extreme variation of lighting.
However, I did find the Picturenaut experience more enjoyable – there is a real feel to what you are doing with the sliders and the preview gives a realistic view of the final image. I will certainly be looking more at Picturenaut and for those not wanting to buy Photomatix Pro, Picturenaut is a very real and very free alternative.