Sunday, October 28, 2007

A Pano from the Show

I've been meaning to swing by the show of my, Margaret's and Kathy's works at the LBJ Wildflower Center before it closes, in order to shoot some panoramas by which to remember it. I shot a few shortly before closing time this Saturday, October 27th. There were a few people taking-in the show even at that hour, which was nice to see, and left me tempted to introduce myself, and offer to answer any questions they might have had about the images or the ranch. I suppose they might have enjoyed that, I also suppose that they might have felt waylaid by an emotionally needy artist. So I shelved that urge and shot panos until the security guard came-in to lock-up. Below is the first of those panos that I've assembled. It includes about 40% of Margaret's drawings, 75% of my panos, and most of Kathleen Marie's photos, although none of these works can be appreciated in the available resolution. It does, however, capture some of the nice setup the Wildflower Center has provided for the show.

Photographically, the scene presented some serious challenges. One was the white balance; with the scene illuminated by direct and reflected sunlight, along with one or more types of artificial lighting, there was no single white point that would be correct for the entire image – more like three or four. There's no way that I know of to reconcile all of them, although I can imagine a white balance algorithm that would apply different pre-established white point corrections to separate areas of an image, while gracefully interpolating plausible white points for the areas between the pre-established points. Tone-mapping algorithms already perform similar spatially-adaptive work on other aspects of images, so I don't think I'm going out on a limb with this notion. Unfortunately, I don't have time to try coming-up with an implementation of my own. In any case, a lot of color-tweaking brought this image to a reasonable compromise among its varied white points.

The other challenge in this pano was that, even when shooting three "raw" exposures (at separations of two f-stops) of each segment of the panorama, the sunlit world outside the windows still ended-up overexposed. Unfortunately, my camera has neither support for automatically shooting more than three separate exposures at one time, nor for increasing the difference between them to anything beyond two f-stops. Perhaps when I return to finish shooting the show, I'll try manually shooting the additional exposures that these scenes need, but doing so introduces a lot more opportunities to make mistakes, and seriously slows-down the shooting process, which causes its own problems.

One of these days, I hope, we'll have affordable cameras with the kind of native dynamic range in their sensors that will make the multi-exposure approach obsolete. That'll leave the current crop of high-dynamic range photographers with a lot more competition, but I'm looking forward to the development of such cameras, nonetheless.

(On the other hand, I run into a lot of photographers who don't mind their skies showing-up white when they were actually blue, etc., and who are, therefore, perfectly happy living within the constraints imposed by shooting JPEG images, even when they could just as easily shoot "raw", and thereby eliminate at least some of those dynamic-range limitations. I don't understand that, but there are a lot of things I don't understand, and perhaps I'm so hopelessly outside the mainstream, that there won't turn-out to be enough of a market to justify the development-, or sustain the production-, of cameras with the ultra-high-dynamic-range sensors for which I'm waiting. It'd be a shame if things worked-out that way, but the successes and failures of technologies have surprised me before, and, doubtless, will again.)

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