Full scale assessment of pansharpening methods and data products

Abstract

Quality assessment of pansharpened images is traditionally carried out either at degraded spatial scale by checking the synthesis property of Wald's protocol or at the full spatial scale by separately checking the spectral and spatial consistencies. The spatial distortion of the QNR protocol and the spectral distortion of Khan's protocol may be combined into a unique quality index, referred to as hybrid QNR (HQNR), that is calculated at full scale. Alternatively, multiscale measurements of indices requiring a reference, like SAM, ERGAS and Q4, may be extrapolated to yield a quality measurement at the full scale of the fusion product, where a reference does not exist. Experiments on simulated Pléiades data, of which reference originals at full scale are available, highlight that quadratic polynomials having three-point support, i.e. fitting three measurements at as many progressively doubled scales, are adequate. Q4 is more suitable for extrapolation than ERGAS and SAM. The Q4 value predicted from multiscale measurements and the Q4 value measured at full scale thanks to the reference original, differ by very few percents for six different state-of-The-art methods that have been compared. HQNR is substantially comparable to the extrapolated Q4

Multispectral Pansharpening with Radiative Transfer-Based Detail-Injection Modeling for Preserving Changes in Vegetation Cover

“…The spectral consistency of Khan's protocol strictly implements the guidelines of Wald's consistency property. The crossed coupling of the QNR and Khan's protocols is preferable, and a global index, referred to as hybrid QNR (HQNR), was recently introduced and validated [56]:…”

Bridging Ridge-to-Reef Patches: Seamless Classification of the Coast Using Very High Resolution Satellite

“…The principle is to decompose the imagery at various spatial resolutions, so that the details of the Pan image can be injected into the original MS dataset. The most successful decomposition functions are the generalized Laplacian pyramid and redundant shift-invariant wavelet and contourlet filtering of the Pan band [35].…”

“…Some protocols exist for evaluating the quality of fused images, such as the Khan's protocol, which integrates the properties of other protocols in order to define spectral and spatial quality indices at full scale [35]. In the near future, the composite technique will be assessed with those recent progresses in quality measures in order to compare its efficiency with other techniques.…”

Image Degradation for Quality Assessment of Pan-Sharpening Methods

“…However, as [14] mentioned, fusion at degraded scale uses the cascade of the low-pass filter of the fusion methods with the lowpass filter used for decimation. This means fusion at full scale and degraded scale uses different filters.…”

“…The first strategy is to employ indices that do not require the availability of the reference image, such as Quality with No Reference (QNR) [12] or Khan's protocol [13], to assess pan-sharpened MS images by some predetermined rules, which introduce more assumptions and problems. The second strategy which came into being recently inspects the trend instead of single measurement at a given degraded scale by Wald's protocol [14,15]. However, these methods introduced more assumptions, and Wald's protocol is still the most reliable.…”