resolution question...

P

perhaps

Active member
ok, i've been trying to get a grasp of everything related to digital video and what not..but one thing i still don't know if exactly what resolution should the final digital footage be at?

i'm no stranger when it comes to print.. i mean, when i need to do a print job for someone in Photoshop, i setup my resolution in inches (for instance, 8x10"), and set my DPI to 300 or so. when it prints out on paper, the image is exactly the same size as i specified on the computer.

but what about DV footage? what i guess i'm really asking is, on a professional film like 28 days later, what resolution do you think they edited the entire video at on the computer? i'm assuming it had to be pretty darn big, but how big? how large should the resolution be if it's going to be transferred eventually to a format like 16mm or 35mm? or even if it's going to be displayed on an HD television, what's the "best" resolution for the video to be stored in?

i'm just a little iffy on how the resolution correlates to "real life" projection.
 
Re: resolution question...

All DV video is exactly the same, it's all 720x480 (NTSC) or 720x576 (PAL). DPI is an irrelevant statistic because there are no standardized monitor sizes; you may be watching on a 2" LCD TV or a 102" projection screen, but it'll all still be derived from the same 720x480 pixels.

When going to film, a digital up-rezzing is usually performed. DVFILM.COM up-rezzes to 1920x1080 before transferring it to film.
 
Re: resolution question...

i could be totally off my rocker, but as far as i know 720x480 is about 10x6.667 inches.. now, that's clearly much, much larger than 35mm, so why couldn't that resolution simply be transferred down to the 35mm size? surely, 10 by 6 inches can hold much more visual detail than 35mm can, so why is it necessary to uprez it even further before squashing it down to 35?

excuse my ignorance :]
 
Re: resolution question...

but its only at 72 DPI  film can be scanned from 35mm at 4k res.. - the optical clarity is quite different.  thats 4k res from apx 1 1/2 inches. thats way ..way more DPI.. its more dots per mm in fact.
 
Re: resolution question...

720x480 is not 10x6 inches, it is not any size at all, it is 720px x 480px. IF you were to print an image that was 720x480 at 10x6 inches it would not look good at all, it would look more like a newspaper image, but with less detail. you stated at the top that you work with photos a lot, so let me put it in easier to understand terms. and 8x10 in photo at 300dpi is 2400px x 3000px. So if you wanted to see the size of an image from a 720px x 480px @ 300 dpi, it would be 2.4 x 1.6 inches. A 35mm frame can actually be blown up much larger than 10x6 inches. And a print doesn not have more information than a 35mm film chip. There is much more info in the film, it is just smaller. I hope this makes more sense, you just have to realize that shooting digital is not even close to the resolution as shooting film.
 
Re: resolution question...

thanks man.

i guess my next concern is how 35mm can hold so much information? also, you said "35mm film chip"..was that a typo of clip, or what "chip" do you mean? anyway, does the 35mm frame hold so much more visual info because of an extremely high dpi or something? i suppose this is a really broad question (how can something so small be so detailed), and i guess i should look it up elsewhere :P
 
Re: resolution question...

..i think hes deriving the figure from DV video being translated to 72 dpi. so the math works out , but its not intended for printing. its really a non issue. were dealing with 720x480 vs 2k or 4k film res. regardless of the "would be print size" or how compact the image is. the optical clarity able to be derived from these differentiating pixel amounts should be somewhat obvious. like a micro fish.. very very high dpi equivelent printing.. its very small but optical clarity is good. if micro fish was only printed at 72 dpi at the same size equivalent it would looks like an ink blotch because what can be resolved optically that small cannot be resolved in 72 dpi.. you need smaller dots/pixels to resolve such a clean optical image from a smaller area.. stretch 4k film image out to 72 dpi and youd have a very huge image. so like scharky said.. 35mm film has alot more info(equivelent DPI) packed into a 35mm film frame.. its very clear when projected optically. 72 dpi just doesnt even come close.

a very easy experiment would be to make a photoshop file at 720 x 480 and 72 DPI at your given printing output size. then zoom in as far as you can. now make the same image at 2k or 4k film res at 35mm print size and zoom in the same amount. you see the film res has more detail. so you can blow it up ALOT more without distortion. even though its smaller .. it has way more pixel definition and detail.
 
Re: resolution question...

Yeah, this is really a strange subject as it is comparing apples and oranges essentially. It is all just a matter of resoution. Mini DV is relatively low resolution, 35mm photo film and 35mm motion picuture film is very high resolution. that is the difference. Physical size really means nothing.
 
Re: resolution question...

Let's sum it up like this: a frame of DV video has about 350,000 pixels. To scan frame of 35mm movie film and capture all the detail, you'd end up with about 12 million pixels.
 
Re: resolution question...

[quote author=Barry_Green link=board=Events;num=1105819604;start=0#8 date=01/15/05 at 13:51:21]Let's sum it up like this: a frame of DV video has about 350,000 pixels.  To scan frame of 35mm movie film and capture all the detail, you'd end up with about 12 million pixels.[/quote]

Hey, can you find out the pixel difference between a frame of 35mm film and a frame of HD video? If the figures are substantially different, send 'em to George Lucas and see if we can hear the screams of outrage from across the country.
 
Re: resolution question...

Oh man, you just opened up a whole new can of worms. The math isn't hard to do, so you don't really need to figure it out. Which HD resolution do you want to know. Lets stick with progressive, becuase interlaced is not considered for film output. 720p = 1280x720 =921,600 or roughly 1million pixels. 1080p = 2073600 or roughly 2million pixels. So as you can see, number wise there is a huge gap. However, digital does not have film grain, thus allowing it to blow up better than film. Or lets put it this way so somebody doesn't come ream me for that statement. From an 8mm frame I have heard of people scanning it up to 1million pixels, so that is equal to about 720p. But for the most part 8mm film is scanned at DV resolution. So now we are working with very equal resoluitons. When projected on a large screen, which will look sharper (don't want to use the word better becasue that is subjective). Well, some people might say, the 8mm becasue it is film, can be scanned at a higher resolution natively and, well, it's film. Well, actually the opposite is true. 8 mm when project gets very grainy very fast. I am not saying this is bad, that is just what it does. It does not have a very large surface to hold all of that information. So the larger you project it, the larger the grain gets. Now when working with DV, there is no grain (and no I am not talking about digital noise, that is another factor alltogether, but should not be considered under normal circumstances). The larger you project a digital image (assuming processing and uprezzing of the image has been done) you do not see grain, but the imagae will eventually get soft. So technically a digital image can be upsampled much more than a frame of film of similar resolution. If you upsample 8mm film to the same resolution, you are just enlarging the grain of the film.

Now, the second point is, lots of films are digitally scanned edited and then reprinted back on film. What resolution do they scan the film at? Well that depends on how much money they want to spend, but i believe it is safe to say that many films are scanned and printed at the same resolution as that of 1080p HD. Now they can work larger, twice that resoltuion as some films do, but it just costs that much more money. But can you tell the differenc between a 2k scan and a 4k scan. The average viewer, probably not, but some people can, and that's ok. Barry mentioned a 12million pixel scan, which indeed could be done, however, there is no way to edit footage of that size. That would come out to be roughly 30MB per frame, 720MB per second, 43.2 Gigabytes per Minute, 2.5 Terrabytes per hour. So I guess you could do it, but I sure as hell wouldn't want to. Remember that is after editing is done, so with all your raw footage you would be looking at roughly 10-20 Terrabytes. :o
So if I havn't lost you by now, just know that the average viewer will not be able to tell the difference (resolution wise) between HD to film and film to film. There are of corse other factors that go into telling the difference, but that is not what we are talking about here.
 
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