Daily Blog - John E. Johnson, Jr. - June 11, 2008: WE NEED TO UNDERSTAND FILM BASICS WHEN COMPARING MOVIES.
If you read our Movie Renter’s Guide commenting section, you are aware of a discussion about the movie Patton, which was recently released on Blu-ray. There is a lot of discussion about how the high def version looks too “clean”, implying that it was “scrubbed” more than for other movies.
Patton was shot on 70mm film back in the days when 70mm was a buzzword instead of surround sound and computer graphics. Most movies are shot within a very small film space that fits on 35mm film when the film is run vertically. Because the film space is so small, film grain is really quite visible now that we can watch them in 1920×1080 resolution. 70mm films were also called “Roadshow Films”. They usually had seven channels recorded on a magnetic strip alongside the film frames.
There are some other classics that were shot in 70mm too, such as Lawrence of Arabia and Ben-Hur. Although Ben-Hur was filmed with a slightly anamorphic lens, both Lawrence of Arabia and Patton were not, so the image is razor sharp. Also, since the 70mm film space has four times the area of the standard 35mm film space, film grain is barely evident, and in my opinion, probably not even resolvable at 1920×1080, depending on the type of film used.
Lastly, back in the old days, there were not many shadows in the movies (except for the film noir movies in the 1940’s). So, the image just leapt off the screen. Such was the case for Patton. Even when George C. Scott was standing out in the full sun, one can see the slight shadows on his face coming from another direction, indicative of the strong overhead lighting.
So, Patton, in my opinion, is not “scrubbed”. It is not “super clean” due to image processing. It is simply a superb film source from which to create an incredible high def movie disc. When 4k high def arrives, this movie will look even better, while regular 35mm movies (not including CGI-based movies that can be generated at any chosen resolution) will probably not look much different than they do now because I think the limits of picture sharpness extracted from the standard 35mm movie film space have just about maxed out at 1920×1080, and I am speaking of movies shot on film and then digitally extracted from that film for mastering to a Blu-ray disc.
Bottom line is that the film size of the master is very, very important to the final image quality. That is why Ansel Adams shot his pictures with a 4×5 film camera.
June 18th, 2008 at 2:56 am
All this talk about “grain” has got me thinking that many people still need to learn what film grain is all about. It is an overly romanticized term which has been bantered around far too liberally without any sort of understanding of what it really is.
Without getting too technical, film is made up of tiny silver-halide grain particles. These are binary: they are either black or not black, on or off, exposed or not. Film is fundamentally a “dither” process, not at all unlike the way a CMY(K) ink-jet printer works (color in film is achieved with C,M, or Y color dye on grains on different layers). So while the grain size is often taken as the “resolution” of film, ignored is the fact that unlike an individual pixel which can be assigned any shade from a pallet of thousands, it takes a clump of 30 to 40 film grains to do the same.
But how big is grain? It varies of course (larger for “fast” but so called grainy film, smaller for slow but “smoother” film) but by and large we are talking in the range of .5 to 3 microns. In other words there are TENS OF THOUSANDS of grain particles across a 35mm film frame. For years people, even highly respected people in the film industry, have waxed poetic about seeing “fine film grain” in 480 line film-on-video. Hoo-hickey I say!
Here’s a little experiment: print something on your color inkjet printer, then scan it at a VERY high resolution (not exceeding your scanner’s true optical resolution) and you’ll see…not shades of color but rather individual dots of either Cyan, Magenta, or Yellow ink. If we could see film grain, that’s sort of what it would look like (not exactly, but you get the idea).
But we don’t see those individual grains. Ever. Not even when watching 35mm film on a screen several hundred feet across. Thank heavens, as that would look like &^*!. But we do see something which lets us know we are watching film. It is the net visual effect of film grain that is so artsy-fartsy: the placement of the grains on the film is random, so the “pattern” of grain is different for every single frame, and there is even overlapping of grains from the different color layers. What this means is that as the frames progress, the finest details “modulate” so to speak and you get film’s characteristic irregularity, or instability, of the tones, that sort of “shimmering” of everything.
With film-on video, even 1080 line, you are NOT seeing film-grains but you ARE seeing something of the optical effect of it, an effect which is unfortunately very similar to Video Noise (which just complicates things: half the time people talk about grain in the context of DVD, or even HD, I am convinced they are actually mistaking video noise for it). Further muddying the water is that this sort of irregularities manifest naturally in film can be introduced digitally for effect or simply be a by-product of video/image conversions, filters, and compressions…none of which have anything to do with film-grain itself (a digital camera for example often yields a picture which looks grainy due to noise at the CCD and/or internal image processing…and there is no film).
Now, I have not actually seen the Patton Blu-Ray yet, but fact is that simply by having such a large, LARGE area of film to begin with as you do with 70mm, when you reduce it down to 1080 lines, you do “normalize away“ some of that film-grain visual effect. You have many, MANY film-grains contributing to just one video pixel (about twice as many compared to 35mm), so even at 1080 lines there is that much less variance from frame to frame. In other words, the larger the original film, the less of the film-grain visual effect will come across at a given video resolution. So I would expect a 70mm source to look smoother (but again I’m not commenting directly on Patton).
June 18th, 2008 at 12:33 pm
To see if 1080×1920 can resolve the film grain on a pristine 70mm source, could you not just zoom in on the image (say with a pc based software player) to 200% so that you were looking at, effectively, 35mm of film space? This would be limited obviously by the fact that the (digital) resolution would be only 540×960. However, film grain is visible in standard DVD discs of 35mm movies which is resolved at 480×720. So I would think that 1080×1920 could resolve the grain on 70mm film, you just might have to zoom in to see it. I don’t have the equipment (HD player) or I’d try it. But it seems like a simple enough experiment.
June 20th, 2008 at 10:34 am
Actually, Ansel Adams dis a lot of work with an 8×10 view camera, which game him four times the area of film than a 4×5. THat, and his magic in the darkroom, gave a grain-free final image - even when enlarged.
September 7th, 2008 at 9:43 am
Quote
“Without getting too technical, film is made up of tiny silver-halide grain particles. These are binary: they are either black or not black, on or off, exposed or not. Film is fundamentally a “dither” process, not at all unlike the way a CMY(K) ink-jet printer works (color in film is achieved with C,M, or Y color dye on grains on different layers). So while the grain size is often taken as the “resolution” of film, ignored is the fact that unlike an individual pixel which…”
Film is not binary, grain is analogue and grains do not clump together like an inkjet to form tones- that is a myth spread by MR of the luminous landscape and is wholly wrong.
here is how film works:
Film emulsions are generally Ag/Br/I atoms combined into crystals from about 1 - 10 microns in size. They contain millions of atoms and many sensitivity specks which consist of sulfur and gold.
When film develops, it can form anywhere from 3 silver metal atoms minimum up to the entire grain, and grains can be stacked, and therefore the dynamic range of density is analogue in nature and virtually infinite. For practical purposes, it ranges from 0.1 - 3.0 density units in a normal negative B&W film
Here is some info from an Expert
http://motion.kodak.com/US/en/motion/Hub/nRodriguez.htm
see question two?
Q: What are the main differences between the way images are recorded on film and digital, aside from resolution?
A: “Film is analog, like the human eye. It sees and records continuous tonal gradations between black and white.
Film is analogue despite what the ignorant jibes of MR suggest