Taking the Sky for a Spin

12mm fisheye lens with polarization and ND filters, varying f-stop, ISO 100, 8 12-20 second exposures for the sky on a rotating tripod (tracking the center clouds), 4 exposures for the sun (rays), and six of varying focal range to build the depth map used on the foreground (to cleanly demarcate its silhouette)

 How it was Made:

Focal Pseudo-depthmap: uses change of focus and calculation of local detail (variance) to determine areas in and out of focus, which can then be transformed into something akin to a depth map. This allowed the clean isolation of the foreground from the sky, lending itself nicely to the creation of silhouettes.

Radial-exposure Composition: the composition of the base 8 exposures for the sky, using preferential blending to the first layer (hence the retention of sharp details). In addition, two normal exposures were used to reconstruct the now horribly-bloomed-out foreground, resulting in the base of our composition






HDR Extraction: over the range of exposures, pixels whose brightness was maxed out were transferred to a blend layer and blurred, then used as a multiplicative mask on the next-darker photo, ideally capturing the detail that was lost- or, if not, blooming the area out much as the human eye might perceptive.






Contrast and Detail Correction: After the composition of base and HDR layers, the detail lost to HDR tonemapping (ie, the bloom/blur or color aliasing) is extracted by summing the difference of each exposure to the composition of base and bloom, then modulating the corresponding pixel in the final image in HSV space (for more natural color interpolation).





Silhouette Light Bleed / Edge Blending: We now take the contrast/detail correction layer (which used the masked image, but was not masked itself) and subtract, clamp, and desaturate the HDR layer, giving us an exaggerated map of the light contributed to the silhouette by our non-masked scene, to which some artistic liberty is applied in adding to the final image. This lessens the sudden change of lightness in transition, and removes any errors in depth calculation performed above.



Although often a long, convoluted process, there's something indescribably rewarding about unearthing the beauty in any scene, whether it be the peak of a mountain or simply the neighborhood park (guess which one this was). Despite the artistic liberties often necessary, I believe one of art's greatest strength to not be conveying the empirical, but capturing the perceptual, human aspect as reflected in the artist's eye.