Fhrx

This is my understanding. Is this correct?

Digital TV
1.78:1 (16x9)

Pan and Scan
1.33:1 (4x3)

Widescreen
1.85:1

Anamorphic
2.35:1

-------------------------------

SDTV (NTSC or National Television System Committee)
525 lines @ 60Hz

HDTV
1080 lines

PAL (Phase Alternating Line)
625 lines @ 50Hz
-------------------------------

Have I got this right? Just wanted to make sure I understand.

palebluedot

Digital TV(DTV) is just a general term for digital TV and it has nothing to do with screen size and can be any aspect ratio.

1.78:1 = 16x9

Pan & Scan is a process where a widescreen movie can be put into a 1.33:1/4x3 ratio. Not all 1.33:1/4x3 movies or TV shows are pan & scan.

Widescreen, when pertaining to movies, is a general term to let you know that the movie is in a widescreen format. The aspect ratio used is usually what the movie was originally filmed in.

Widescreen, when pertaining to TVs, is also a general term but for the most part it is referring to a 16x9 TV.

Anamorphic has nothing to do with screen size or aspect ratio. Anamorphic is a process used when authoring a DVD which, basically explained, allows for the greatest possible resolution for the transfer.

NTSC does not specifically pertain to just SDTV. It encompases all forms of all television SD, DTV, HD, etc...

SDTV is an interlaced signal 525 lines of vertical resolution but only 480 are visible.

HDTV can either be 480 interlaced, 480 progressive, 720 progressive and 1080 interlaced.

I know nothing about PAL.

[Edited by palebluedot on 03-01-01 at 09:47 PM]

Fhrx

Ah ha, ok. Thanks for clearing that up Palebluedot.

Could you explain anamorphic a little more for me dude? I was just reading this guide from The Digital Bits and I'm still a little confused as to how it works technically.

http://www.thedigitalbits.com/articl...hic/index.html

Thanks for your help.

palebluedot

Basically anamorphic is a bit that gets turned on in the DVD authoring process that "squeezes" the picture rather than letterboxes it and when you play the movie your DVD player and TV will "unsqueeze" it. That is what the 16x9 mode on your DVD player is for(you would also set it to 16x9 even on a 4:3 TV that has an anamorphic feature like the Sony Wegas). However if your TV does not have an anamorphic feature you would set your DVD player to 4:3 which basically does on-the-fly letterboxing for you.

In letterboxing the resolution is lower because the "black bars" are using some of the scan lines in order to produce the widescreen movie. Anamorphic only works on digital TVs or TVs with an anamorphic feature.

Anamorphic also works in the theater. If a theater has only a 1.85:1 screen, a 2.35:1 aspect movie would obviously be to wide for the screen. What they do is they put an anamorphic lens in front of the projector to "squeeze" the picture onto the screen but retaing the original ratio of the movie. In most theaters though, they have 2.78:1 screens and they move the side curtains depending on the aspect ratio of the movie.

Fhrx

Thanks heaps for that. That makes it much clearer.

Good man, Thanks!

reverb

Okay... Some clarifications (I live aspect ratios)

First, for all practical purposes, do not correlate anamorphic film production and projection with anamorphically enhanced transfers for DVD. Different animals. Many people mistakenly do this.

Here's a pretty good list of ARs:
1.33:1 (16mm film, NTSC TVs, NTSC video cams)
1.37:1 (old academy 35mm aperture)
1.66:1 (standard European 35mm 'widescreen', super16mm)
1.78:1 (HDTV, 'widescreen' TVs, 'widescreen' video cams)
1.85:1 (35mm 'widescreen', anamorphic 16mm)
2.35-2.42:1 (anamorphic 35mm, spherical 2.35:1 on super35mm)

That said, you can shoot any of these ARs on 35mm film, and most on 16mm film. Film has no inherent AR. For instance, I regularly work with super35 with a 4:3 AR on commercials.

For an in-depth discussion on some of this, check out this thread. I discovered errors in the Home Theater Forum Aspect Ratio FAQ, which is now being corrected, and we discussed it here (I'm Scott):
http://www.hometheaterforum.com/uub/...ML/001550.html

Some info on projection:
http://www.hometheaterforum.com/uub/...ML/006020.html

My recent PAL rant (PAL is far superior to NTSC video):
http://www.dvdtalk.com/forum/showthr...threadid=82220

reverb

This is incorrect.

Anamorphic projection of a feature film in a theater expands the image at a typical ratio of 2:1 along the horizonatl axis, thus expanding the image not "squeezing" it. For practical argument, screens don't have an AR, but are matted by curtains (or similar) to the AR being projected. An anamorphic print must be projected through an anamorphic lens, otherwise the image would be horizontally compressed and objects (image data) would appear skinny (but not tall) - and it would appear at the wrong AR to boot.

reverb

Well, it does, in that to achieve a c2.4:1 AR on standard 35mm motion picture film one must utilizes anamorphic lenses (Scope/Filmed in Panavision, et al). And to end up with a projectable anamorphic film after shooting spherical 2.35:1 on super35 one must do an anamorphic extraction and a print reduction to regular 35. BTW, there is no difference between regular 35 and super35 film stock, it is simply a different method of shooting, specifically a different image alignment on the camera negative.

Anamorphic is a method of shooting film by which you can achieve wider aspect ratios on standard 35mm motion picture film, a method which became popular in the early 1950's. Only recently has it begun to be utilized as a means to enhance the resolution of film to video transfers for optimal playback on 16:9 monitors

[Edited by reverb on 03-02-01 at 01:44 AM]

Fhrx

Thanks heaps for your answers guys. That's just the info I needed!