Nonsense. Your non upconverting DVD player example isn't real. If it was, it would be an 'upconverting' DVD player that just so happens to do a horrible job. If it doesn't upconvert, it's not doubling the pixel, it's not interpolating it... it's just sending everything at the native resolution and letting the TV do with it as it pleases.
And when the TV "does what it pleases" what do you think it's doing?
Most often it's exactly what I showed.
I suppose I could have been more clear and instead of putting "
Regular DVD Player" I could have written "
What the HDTV does to the SD signal sent by the non-upconverting DVD player" but I figured that would be tough to fit on the line.
Cramming all that extra text in there makes it more technically correct, I suppose, but it doesn't change the basic example. It would STILL be 'red red blue.'
(And if I am wrong and you think it DOES change the answer, then please tell me what the middle-pixel should be in that example. You said I was wrong but neglected to tell me what the right answer would be. If I'm wrong I'll admit it, but you still haven't given an alternative for me to consider.)
Here's why you're wrong. You declared that 'upconverting' improves the picture. It doesn't. Scaling the image is a necessary evil of having fixed resolution displays. By trying to add detail that isn't there, you're diluting the detail that is there. I like how you even used the word 'smoothness' to describe the upconverted picture. Personally I'd have gone with 'bluriness'.
As for what I think the TV is doing when you give it the original resolution... well, unless it's a complete piece of shit, it's not doing the nearest neighbor type nonsense that you're describing. My five year old Sony scales stuff very well, actually, there's no big improvement that an upconverting DVD player could bring. And if you did buy a complete piece of shit, it's a little strange to be so concerned about video quality!
But fundamentally it makes a lot more sense to have your TV scale the source resolution to its native resolution. Let's say 10 years from now you have, oh I don't know, an '1800p' television. You want to watch your DVDs in the best quality so you bust out your awesome 'upconverting' DVD player... which scales the content to 1080p, and then is again scaled by the TV to the final resolution of 1800p. Congratulations, you now have a worse image than if you had a DVD sending 480p to the television because you've introduced an extra resize to the process!
Anyway, if your TV does suck at scaling, there's still not much of a point of buying a standalone upconverting DVD player. Just spend a little more, get a PS3, or a standalone Blu-ray that does a decent job of scaling, and voila! So yeah, Trekker4747's main points are valid. Upconverting DVD players are largely worthless, and the upconverting process does not improve an image.