A 2015 paper, "Practical Methods to Validate Ultra HD 4k
Content," by Arris' Sean McCarthy, details software techniques to test "how 4k is
it" (upcoming Blu-rays, etc.). See:
Or, if server error, visit Arris.com or Google paper title.
High-quality scalers in 4k displays make it hard to tell whether you're seeing
upconversions or original 4k effective resolutions, he writes. The software used
for 4k evaluations mathematically breaks down UHD video using a Fast Fourier Transform (FFT), then displays 4k
content levels graphically. A similar method, with a graph from still-available
shareware, was used by avser dr1394 to analyze a sports-stadium scene:
(below luma frequency/level plot) for HD effective resolution content. Footnote 10 in the pdf shows number-crunching software, too.
Figures 6 and 7 illustrate how 4k UHD effective resolution levels change depending on
mixed grades of scaling, or varying compression levels. For example,if the orignal
2160p-resolution scene (left, Fig 6), with maxinum UHD resolution is instead delivered
in three different separate steps, down to 480p (right Fig. 6) before upscaling to 2160p
again, the log computation of the data and plotting becomes a gradually smaller oval
pattern. Similarly, this 'contour-map' pattern results from gradually increasing HEVC
compression (Fig. 7), which decreases higher-frequency content, making smaller ovals.
Results can be used for production or test libraries, etc. (Maybe high-end home hardware
could graphically display effective resolution with testing.) -- John