ceci vient d'un autre guru de la video sur AVS. croyez moi, il connait le sujet. j'essaierai de retrouver les propos de Joe Kane aussi: notez que son propos ici fait d'abord reference au tritube mais aussi au digital et qu'il insiste sur 2 choses: l'upscaling de la source ET un display haute résolution.
"Well, DVD frames consist of only 720x480 pixels for NTSC. People often argue that showing these frames upscaled to any resolution above that (1024x576, 1280x720 or 1920x1080) is a waste of time, because "there isn't more information than 720x480 anyway" or "you can't create detail from nothing".
While both statements are true, they COMPLETELY miss the point!
Upscaling 720x480 to a higher resolution is not about creating 'detail' that isn't there in the first place. Its about presenting those 720x480 pixels on a display device with the least possible amount of high frequency aliasing noise.
Huh? Ok, only because you have 720x480 SAMPLES of an analog medium (like film in this case), doesn't mean that displaying them AS SQUARE PIXELS WITH SHARP BOUNDARIES on a display device is the right form of output to reapproximate the smooth analog waveforms it originally captured! By upscaling digital samples to a higher resolution, you interpolate a smooth waveform between the discrete samples. The more interpolation steps the better. The ideal would be to use a sinc filter that yields a sine wave, but thats currently too demanding processing power wise. A typical interpolation that is used is bicubic filtering, which is already better than bilinear filtering, but not quite spline or sinc quality.
If you are a bit familiar with digital information processing in the audio domain, you will see that this is exactly the same concept that is used in DACs in CD players for years. Its called oversampling. Think of the same thing in 2 dimensions and you are there.
So, again. Displaying 720x480 samples as square pixels means that the difference between the square waveform and the ideal sine waveform is noise that masks the actual detail in picture. This is what we perceive as 'aliasing'. The harsh edge of the square yielding very high noise in the frequency domain (fourier).
That is why watching a DVD on a high resolution device (e.g. 9" CRT) at a high resolution like 1920x1080 does actually reveal MORE detail (of that original 720x480) than a 800x600 digital device, because actual detail is masked by less aliasing noise that distracts the eye. "
http://www.avsforum.com/avs-vb/showthre ... genumber=3
maintenant, cette puce 1024x"576" rendra en fait mieux la resolution dvd que une puce 800x600. de meme une puce 1280x720 encore mieux etc etc
en 1024 horizontal, cela laisse 435 vertical en 2.35:1, ce qui est deja plus que la resolution verticale d'un dvd d'un format scope. par exemple.
: est-ce une vraie matrice 1024x576 ou bien une matrice bi-mode 1024x576 / 1024x768 ?
Créé le 19 Jan 2004 12:06
