^^^Yeah, the S-M disc creators outline potential difficulties, too, (at my link). But, if you see differences between 480p and the best-resolution 1080i/p sources it should be possible to measure it (max effective resolution). The oft-repeated garbage-in/garbage-out. -- John
I've never used a loupe/reticle device before, so how easy would it really be count the effective lines of resolution of a 480p YT vid upscaled to 1080p? I feel like some signals/internet feeds are so poor to begin with that even with a magnification device, it would be difficult to determine.
The link above to a 9X comparator and fine-ruled reticle shows what you'd see with the lens against a direct-view screen (sans image). You Tube etc. videos are indeed often fuzzy. Scaled to 1080p by your display, the finest visible details remain fuzzy; they're just larger on a screen meant for consumer motion video. While a detail, say a human hair, is fuzzy, placing the reticle over it gives you a reference measurement: how many reticle-line divisions wide.
That reference measurement could be compared with test patterns until a similar or identical width is found. (Referring here to fine vertically oriented details--a hair--to measure maximum effective horizontal.) The horizontal rule in the reticle (linked above) would be turned 90 degrees to measure vertical resolution detail, then compared with vertical-resolution bursts. Here are the vertical and horizontal bursts
on the S-M test Blu-ray. My link earlier to the S-M test disc thread discussion mentions how to convert the frequencies given to lines of resolution.
For a 1080p display, of course, the 37.09-MHz vertical-lines test pattern (2nd row down, far right) should have 1920 B&W lines across your screen width--perhaps confirmed by counting lines per inch and calculating per screen width. But as the S-M test disc developers point out, that's not the purpose of their resolution-burst patterns. Some years back one AVSer mentioned he used a pro computer graphics program to create his own lined patterns to measure resolution. Also, an upscaled 480p image measurement on a 1080p display could be compared with similar measurements but wouldn't represent the original 480p resolution. Ideally, this technique would be used to compare mostly 1080 image details, factoring in upscaling if other capture/production resolutions are used.
But a measurement such as this could provide the equivalent (test pattern) maximum horizontal resolution, just for comparison purposes, of what might appear to be the finest detail on a You Tube image (for similar upscaled comparisons). A Blu-ray movie, even with all the resolution limitations mentioned in the S-M disc discussion, could be similarly measured for what appears to be some of the finest details--ditto for live or recorded 1080i broadcasts--although live programs would need frame grabbing, DVRing, etc. for measurements. -- John