High Dynamic Range Imaging

Abstract

The ultimate in color reproduction is a display that can produce arbitrary spectral content over a 300-800 nm range with 1 arc-minute resolution in a full spherical hologram. Although such displays will not be available until next year, we already have the means to calculate this information using physically-based rendering. We would therefore like to know: how may we represent the results of our calculation in a device-independent way, and how do we map this information onto the displays we currently own? In this paper, we give an example of how to calculate full spectral radiance at a point and convert it to a reasonably correct display color. We contrast this with the way computer graphics is usually done, and show where reproduction errors creep in. We then go on to explain reasonable short-cuts that save time and storage space without sacrificing accuracy, such as illuminant discounting and human gamut color encodings. Finally, we demonstrate a simple and efficient tone-mapping technique that matches display visibility to the original scene.

Sparse DP Quantization Algorithm

“…Each path in the trellis transition diagram has a cost that is quantization error for a histogram interval determined by both endpoints of the path. For example, the cost of the path from node (1, 0) to node (4, 1) becomes the quantization error caused by quantizing the histogram interval [2,4] as the second bin. Quantization shown in Fig.…”

“…As described in Sect. 2, the boundary of each bin is in the range defined by inequality (2). In Fig.…”

“…In Fig. 4, the blue broken line and the green broken line correspond to superior end and inferior end defined by inequality (2). Thus, the optimal path is restricted to candidates that pass through nodes located between the green broken line and the blue broken line.…”

“…This is because there are no possible paths to transit from the node (4, 1). The destination to transit from the node (4, 1) is only node (5, 2) and (6,2), which are insignificant nodes. Thus, as the rightmost node in this row, we select node (3, 1) indicated by a blue circle with the numeral of two.…”

“…This manuscript focuses on the latter type. The latter type is a kind of bit depth conversion, and is required for display adaptation [2], [3], bit-depth scalable coding [4], [5] and HDR video coding [6].…”