question of rear projection resolution?

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Recall a review a year or so back of a Mitsubishi set with 9-in guns. They apparently used a high-end pattern generator able to sweep through a range of frequencies and reported the set resolved 1600 lines. A former contributor here who brought a high-end generator into stores and tested many HD sets, reported seeing a Philips 9-in-CRT RPTV, a model I purchased in 2000, resolve in the mid-1600s. Not really concerned about the Philips' resolution anymore, but if a zero/low-cost means of testing crops up one of these years I'll give it a try.


The usual point, which I outlined again recently and expanded slightly, is that 1080i delivers 1920-pixel-wide lines but the pro recorders used for broadcast apparently deliver resolvable details (other than test patterns) only requiring ~1440 or 1300-pixel resolution. -- John

Since most CRTs can only resolve 1200 lines is it safe to say that there is no visual benefit in having 1080i content ( 1920 lines ) vs 720p (1280 lines) on these sets? The interlaced signal should only introduce motion artifacts, and the CRT is unable to reveal the final detail of static 1080i image.

Why then do some claim that they 1080i produces a better picture on their (7" crt based ) RPTVs than 720p?

Yes, that's Joe Kane's point about 720p versus 1080i (both get about the same resolution quality from broadcast gear). But, like most others here, I find 1080i provides crisper images than 720p. Suspect, because differences may be slight for some systems, such comparisons could become very subtle. One aspect: both 720p and 1080i as they're delivered and viewed undergo similar resolution reductions. This is evident when you compare resolution measurements with test patterns in this table . But test patterns aren't compressed as severely (or at all) compared to detailed motion video. So, while both formats are resolution limited during production and transmission, 1080i still appears to be delivering more detail. The 1080i/p format, of course, has lots of room for 'growth' horizontal resolution wise (post I mentioned above), while 720p is format-limited at 1280 pixels. -- John

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This seems to work. Powerstrip and Displaymate running together. Using Powerstrip, set desktop in a HDTV compatible mode with horizontal pixels that you want to test. Then run Displaymate, it will recognize the mode you are in. Select Horizontal res Test pattern. It won't be jfamiliar wedges, but it will test: full res, 2/3 res, 1/2 res...


To get Wedge results, redo entire process with new Powerstrip setting which will change the "full res" that Displaymate produces.


Takes a little longer, but seems to work. At any rate, its lot cheaper than a sencore!


Preliminary Results, (on a Sony): 960 => clear lines, 1280 => can see the lines clearly, but contrast starting to suffer. 1920 => gray field

Thanks for the Displaymate tip, Dave. The price seems reduced from a year or so back. Back then I also noted a very stiff price for a pro version that provides rotating patterns for testing dynamic resolution.


Don't get HDNet here, so can't use their periodic test patterns (see recent programming-forum thread). But perhaps, since video-on-demand cable firms now provide movie trailers at no charge, they'll devote a small hard-drive segment to permanent SDTV/HDTV test patterns that new HD-VOD subscribers can call up 24/7/365. I e-mailed my cable firm's VP/programming requesting such a feature. -- John

That would be way cool John. Hope you're successful!


I got the Displaymate because I never seem to be home when HDnet broadcasts the test pattern. (Had been using crude test pattern bmaps I genrated myself. it was pretty humourous...)