Figure 1: sPDF-maps are a compact multi-resolution image pyramid data structure that sparsely encodes pre-computed pixel neighborhood probability density functions (pdfs) for all pixels in the pyramid. They enable the accurate, anti-aliased evaluation of non-linear image operators directly at any output resolution. A variety of operators can be computed at run time from the same pre-computed data structure in a way that scales to gigapixel images, such as local Laplacian filters for (b,d) detail enhancement or (c,e) smoothing, (f) median filters, (g) dominant mode filters, (h) maximum mode filters, (i) bilateral filters. The original image (a) has resolution 16, 898 × 14, 824 (250 Mpixels).
AbstractWe introduce a new type of multi-resolution image pyramid for high-resolution images called sparse pdf maps (sPDF-maps). Each pyramid level consists of a sparse encoding of continuous probability density functions (pdfs) of pixel neighborhoods in the original image. The encoded pdfs enable the accurate computation of non-linear image operations directly in any pyramid level with proper pre-filtering for anti-aliasing, without accessing higher or lower resolutions. The sparsity of sPDF-maps makes them feasible for gigapixel images, while enabling direct evaluation of a variety of non-linear operators from the same representation. We illustrate this versatility for antialiased color mapping, O(n) local Laplacian filters, smoothed local histogram filters (e.g., median or mode filters), and bilateral filters.