Dork(original) Posted May 24, 2008 Posted May 24, 2008 My brother asked me the other day,"Is Hd better than film?"I said i don't know.So where does film sit in the scale of resolution? Paul.
minchjp Posted May 24, 2008 Posted May 24, 2008 My brother asked me the other day,"Is Hd better than film?"I said i don't know.So where does film sit in the scale of resolution?Paul. Film is an analogue format, but it is scanned into a digital editing suite at 4k. See Here for more information. HD at a maximum is 1920x1080, so Film would effectivley have a mich higher resolution
alanh Posted May 24, 2008 Posted May 24, 2008 minchip, Film resolution depends on the film frame size. For example 16 mm film is really only SD resolution, Super16 is TV HD resolution. All 35 mm film and bigger is higher than TV HD. There is a much newer standard than the references used in the Wikipedia article. Digital Cinema standards 2K: 2048 x 1080p @ 24 frame/s. The reason for this standard is to use an anamorphic lens to double the width of the image for the same resolution. 4K: 4096 x 2160p @ 24 frame/s. The system used satellite transmissions to digital projectors in cinemas. No film is used at all. The system is encrypted to prevent copying and the decription occurs in the projector itself. I also disagree that the resolution of an interlaced scan and a progressive scan is the same. Film is not really analog. A microscopic examination shows that the image is formed in the film by the number of grains of silver which are converted to silver when exposed to light. This is "amplified" by development during processing. This this film is scanned in its negative form by a digital telecine. This is the chink in the chain because this device uses a analog light detectors whose outputs are then digitised again. If however the film is then ether converted to a positive or printed the silver is used to make the yellow, cyan and magenta dyes to stay clear or become one of those colours then it becomes analog. AlanH
ckent Posted May 28, 2008 Posted May 28, 2008 Further to that, there is no direct relationship between film frame sizes and resolution. If you look at the quality and manufacturing process of film over time, you'll find the same frame sizes increase in resolution as the years go by. Also it's probably vital to point out that any measurement of the individual silvers in a film frame needs to account for the fact they're not lined up neatly in rows and columns. All you can really say is that a certain type of film size, from a certain type of stock, has a maximum effective resolution after transfer to digital (assuming you are using the latest / expensive techniques). That goes part of the way to explaining why, if you bring your Full HD handicam to the local cinema, you won't even get far beyond DVD quality, if that. CK.
alanh Posted May 28, 2008 Posted May 28, 2008 ckent, There is an advantage if having random sizes and random positioning, that is that moire is not produced on fine patterns as it is in TV. Film manufacture, in particular the reduction of space between the "grains" has become much lower increasing the sensitivity of the film to light. To do this the grains have to be more regular in shape so as to "fit together" and to increase resolution without too much drop in sensitivity. They can only make the grain a fixed size with a particular manufacturing method, so the bigger the actual frame the greater the resolution. It also means that it is less demanding on lens systems as well. It will be interesting to see what effect nano technology has on film manufacture in the future. Your last statement is untrue because when film is fed through a 1920 x 1080p telecine at 24 frame/s it produces the result you see on Blueray. If you take your camera to the local cinema there is a few problems 1. You are viewing a release print which will have been optically copied from the master through at least one generation if not more. 2. The quality of the projector lens. 3. The steadyness of the image in the gate of a claw mechanism. Telecines use a continuous motion so the film does not have to stop for each frame. You are expecting each frame to stop in the projector gate to within an accuracy of better than 0.01 %. This also assumes the sprocket holes to be this accurate as well, particularly after many repeat screenings! 4. The quality of the handicam lens and optics. AlanH
ckent Posted May 29, 2008 Posted May 29, 2008 AlanH, On the film grain — yep I agree with the point about irregular sizes and positioning; I never said it was a disadvantage. But I'm not sure I've read anywhere that film grains have become more regular as they get smaller ... the whole thing is still a completely organic process AFAIK. Anyway, even if the grains are strictly "regular", they're never likely to form rows and columns ... hexagons and honeycomb cells are just as likely. Anyhow I don't think my last statement is untrue ... I was bringing up the point about "using the latest / expensive techniques", which is precisely why a handicam (even a Full HD one) will not produce a great result (which you then went to great lengths to list). Anyway another part of the reason is the film-to-film copy done for the local cinema to use. There are lots of other reasons why a BluRay copy (and even a DVD copy) is going to be superior to a transfer done using a cinema copy and/or a consumer camera. CK.
alanh Posted May 29, 2008 Posted May 29, 2008 Ckent, I suggest you look around this site starting here Read this as well AlanH
alanh Posted May 29, 2008 Posted May 29, 2008 Ckent, Ckent, I suggest you look around this site starting here Read this as well Film specifically made for camera to HD digital telecine only So for the above film emulsion the camera resolution for an MTF of 25 % (50 cycles/mm). Assume a 16:9 aspect ratio Standard 65 mm 4100 x 2300 (as a reference to "4K" Digital Cinema, not used in cameras anymore) Standard 35 mm 2200 x 1600 ("2K" Digital Cinema) 35 mm Anamorphic 1650 x 1880(lens halves the width of the image on the film) Super 35 mm 2490 x 1870 Super 35 mm Wide screen 1780 x 1000 Standard 16 mm 1030 x 750 Super 16 1250 x 740 Ultra 16 1170 x 660 AlanH
ckent Posted May 30, 2008 Posted May 30, 2008 Did you actually read the links you sent me? From the second page: It’s a common assumption that an image recorded on a frame of 35 mm color negative film can be scanned and converted to digital data at 4K resolution. However, testing conducted by our scientists last year indicated that when you scan an image recorded on a 35 mm frame it can be converted to an 8 to 9K digital picture file. Film also has an incomparable dynamic range, which enables cinematographers to record more nuanced colors and tones in scenes with both dark shadows and bright highlights. The most advanced digital cameras can dig deep into the darkest shadows, but they tend to blow out details in highlights. So, look, it's never precise with film, but the rule of thumb is that there's always *easily* more than you need available, as long as you're comparing modern film with modern digital video. So the 65mm film by comparison would then be about 15k or something; look, it's hardly important in the end, since there are too many variables (even from frame to frame) to achieve that theoretical maximum. It's never precise, which was my point yesterday — that's why all the numbers like the ones you've calculated, are always going to be rough estimations, and very conservative estimations, keeping it on the low side! Generally your bottleneck or limitation when just measuring the the physical film is going to be something else, like lens quality or just the ability and patience of your production crew. Even if you could achieve the crazy amounts of 6k or 8k or more, it's very likely that you're not going to care enough to blow the obscene amounts of cash it would take to process that many pixels digitally. You'd just come back to sanity and scan only 4k. CK.
alanh Posted May 30, 2008 Posted May 30, 2008 Ckent, I sure did. I also found out the size of the frames of each type of film format to calculate these values. The TV image whether it be the camera or telecine cuts up the image into pixels. It is essential to limit the frequency response of the video to stop the moire effects caused by edges around the data. This filtering in optics comes from the ability of the lens to focus a spot of light onto one pixel or grain of silver. The best test image to test sharpness of the camera is to measure the narrowest white line on a black background. This should be measured with a waveform monitor from an HD camera or a film camera/telecine combination. It will give a sin2 shape and you measure the width @ 50 %. The % width whole line of x pixels will give you the resolution. This can be done vertically as well. This eliminates the patterning effects of moire. A cycle in the MTF requires a minimum two pixels to display it. ie 1 white an one black. I used the value of 25 % MTF for a film specifically designed for camera capture and as a negative straight into a telecine. I also have not used the complete frame only that which will fit into a 16:9 frame. So I have left out the pixels required for 2.35 aspect ratio. So either the top or side has been cropped to fit. Selecting a Modulation Transfer Factor value is difficult due to the non linear brightness characteristics of film. To achieve the resolutions quoted the speed accuracy of the film through the gate, film stretch and weave must not exceed 0.01 % otherwise the image moves from frame to frame blurring the image. This also means that in production the camera mounting must be very still unless it is appropriate in the script. I totally agree with your other comments which also apply to HD TV production as well. Remember that 4K (4096 x 2160) is the highest resolution mode for digital cinema presentation & production. It would seem that they would make this to match the highest quality which the public have seen before as "70 mm". AlanH
Dork(original) Posted May 30, 2008 Author Posted May 30, 2008 (edited) Film is an analogue format, but it is scanned into a digital editing suite at 4k. See Here for more information. HD at a maximum is 1920x1080, so Film would effectivley have a much higher resolution So Alan and Ckent,is what Minchip states the answer?You blokes know way too much for me."As usual you don't get info you get an education" (with apologies to someone that i pinched that quote from)Thanks for the replies. Paul. Edited May 30, 2008 by Paul_
ckent Posted May 30, 2008 Posted May 30, 2008 Erm, in a sentence: Yes film would, as long as it's the right kind (eg, 35mm) and a reasonably modern formula. It's obvious that you could get a bad frame of celluloid in amongst any strip of film, of course. So you have to remember that each frame of film is more or less different. ("More" in the old days, "less" in these days). Though I guess you could still make a rubbish formula of film stock today, if you wanted to save money. Still, that should be fairly obvious. CK.
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