[Jesse S]

Since 540p is "equal" to 1080i, what if we used doubled, interlaced

res for our CRT's? Would we gain similar benefits as the 1080i scheme relative to 540p?


E.g - I use 1280x720p, would the interlaced equivalent be 1280x1440?


What about that no interlace+overlay problem? Perhaps use VMR9?


Is this just a crazy theory? Discuss.

 

[Jesse S]

It also occurs to me that 1440i is a perfect 3x multiple of NTSC's 480i res.


Also good, in theory...

 

[kal]

True, but only an HTPC can run that sort of 'different' resolution. Most of HTPC'ers use ATI Radeon cards as they provide the best image quality. Problem is that interlaced resolutions no longer work in their drivers if I'm not mistaken... I think they used to be available, but no longer are. Someone correct me if I'm wrong.


That point aside, I still think this is an interesting discussion ... so let's keep it going. Why not 1440i?


Kal

 

[spearce]

1440i is not the same as 720p. Sure, its the same h-sync rate, but it has more lines.


More lines doesn't give you a better picture if the projector can't resolve them.

 

[Andrew_Ballew]

Quote:

Originally posted by Jesse S Since 540p is "equal" to 1080i, what if we used doubled, interlaced res for our CRT's? Would we gain similar benefits as the 1080i scheme relative to 540p? E.g - I use 1280x720p, would the interlaced equivalent be 1280x1440? What about that no interlace+overlay problem? Perhaps use VMR9? Is this just a crazy theory? Discuss.

What is there to gain scaling NTSC material to another interlaced resolution? You gain no more detail whether 480i is scaled to 540p, 1080i, 720p or 1440i. Also, scaling to another interlaced resolution eliminates the ability to perfectly reconstruct progressive film frames. Furthermore, many CRT projectors that could fully resolve all 540 or 720 progressive lines would not be able to resolve all 1080 or 1440 interlaced lines.


The whole idea in scaling NTSC material higher than 480p anyway is to eliminate scan lines on high-res displays. If 720p is the sweet spot on your projector, why bother with what will in all likelyhood be a loss of resolution and a loss of reverse telecine reconstruction?


On a related note, in reference to HDTV, 540p and 1080i are NOT the same thing. In theory one has 540 lines of vertical resolution, one has 1080 lines of vertical resolution.


Andrew B.

 

[Jesse S]

I'm pretty sure it was Karnis who said that 540p/1080i are identical electrically to rptv's. But they use 1080i instead because your eye perceives it as double the res over time. So why wouldn't the same trick work for us to reduce "aliasing noise", as Bjeorn Roy coins it. I've seen accepted explanations for why 1080i is not the same as 1080p so why would that change for 1440i/720p?


Lets think about why we scale; to hide scanlines and reduce "aliasing noise" by filling in the gaps with interpolated information. If the only goal was to hide scanlines there would be no benefit from scaling an 8/9" crt to 960p than using 480-500p on a sony 10xx or 720p on an Nec PG. More interpolation has proved to give a better picture even when the source is the same 480i DVD.


Someone must have more to add here.

 

[cpurvis]

I have only to add that my Radeon 7500 runs 1080i fine, perhaps newer Radeons cannot do interlaced resolutions.