I got this photo during last Sunday’s bike ride. Rock Knob is the smaller mountain (hill?) in the foreground. (It looks more like a huge jumble of boulders in this photo than any kind of defined “knob”.) Part of it resides in McDowell Mountain Park; the rest of it is in the preserve. The McDowell mountain range is behind Rock Knob in this picture.
I was looking for a way to explicate the detail in the rocks. Tone mapping with Fattal does the job really well, but I often find the results jarring to my eyes, even while I admire the degree of detail that the algorithm produces. Fattal also produces some significant halos.
I ended up tone mapping the image with Mantuik ’06. I hadn’t spent much time playing around with this algorithm because the defaults in Luminance HDR don’t produce appealing results. After playing with some of the parameters, however, I started seeing more results that I liked better. These are the parameter values I used:
- Contrast Factor: 0.50
- Saturation Factor: 2.00
- Detail Factor: 1.00
- Contrast Equalization: Enabled
Although I had three exposures to work with, I only used one as the histogram was fairly well contained.
One problem that I had with the result of the tone mapping is that the lower right corner was extremely dark. It was unacceptably dark after level adjustment in Luminance HDR. I ended up adjusting the levels with GIMP instead using a gradient mask in the lower corner to avoid darkening that portion even more.
I found out that the dark lower corner is a known (and unfixed) bug in the implementation of Mantuik ’02 in Luminance HDR. There is another implementation in pfstools. For the image below, I used the following command to do the processing:
pfsin DSC04492.JPG | pfstmo_mantiuk06 -s 1 -e 0.4 | pfsview
I loaded that result into GIMP, loaded the original image, DSC04492.JPG, as the top layer and then set its layer mode to color. Aside from scaling it, I did no other edits in GIMP. Without the color transfer the color was kind of blah. Luminance HDR allows saturation values between 0 and 2; pfstmo_mantuik06 only allows saturation values between 0 and 1, inclusive. I used 1, but there still wasn’t much saturation.
Here is the above image again, with the saturation bumped up even more.
For comparison purposes, here’s the original file, DSC04492.JPG, scaled to be 1080 pixels high.