The focal length is the distance between the pinhole and the film (a.k.a. image plane). For reasons we'll discuss later, the focal length is measured in pixels. In a true pinhole camera, both \(f_x\) and \(f_y\) have the same value, which is illustrated as \(f\) below.
This discussion of camera-scaling shows that there are an infinite number of pinhole cameras that produce the same image. The intrinsic matrix is only concerned with the relationship between camera coordinates and image coordinates, so the absolute camera dimensions are irrelevant. Using pixel units for focal length and principal point offset allows us to represent the relative dimensions of the camera, namely, the film's position relative to its size in pixels.
You can use similar triangles to convert pixel units to world units (e.g. mm) if you know at least one camera dimension in world units. For example, if you know the camera's film (or digital sensor) has a width \(W\) in millimiters, and the image width in pixels is \(w\), you can convert the focal length \(f_x\) to world units using:
Alternatively a digital movie could be a film reel that has been digitized using a motion picture film scanner and then restored, or, a digital movie could be recorded using a film recorder onto film stock for projection using a traditional film projector.
Digital cinema is distinct from high-definition television and does not necessarily use traditional television or other traditional high-definition video standards, aspect ratios, or frame rates. In digital cinema, resolutions are represented by the horizontal pixel count, usually 2K (2048×1080 or 2.2 megapixels) or 4K (4096×2160 or 8.8 megapixels). The 2K and 4K resolutions used in digital cinema projection are often referred to as DCI 2K and DCI 4K. DCI stands for Digital Cinema Initiatives.
TI's technology is based on the use of digital micromirror devices (DMDs). These are MEMS devices that are manufactured from silicon using similar technology to that of computer chips. The surface of these devices is covered by a very large number of microscopic mirrors, one for each pixel, so a 2K device has about 2.2 million mirrors and a 4K device about 8.8 million. Each mirror vibrates several thousand times a second between two positions: In one, light from the projector's lamp is reflected towards the screen, in the other away from it. The proportion of the time the mirror is in each position varies according to the required brightness of each pixel. Three DMD devices are used, one for each of the primary colors. Light from the lamp, usually a Xenon arc lamp similar to those used in film projectors with a power between 1 kW and 7 kW, is split by colored filters into red, green and blue beams which are directed at the appropriate DMD. The 'forward' reflected beam from the three DMDs is then re-combined and focused by the lens onto the cinema screen. Later projectors may use lasers instead of xenon lamps.
In late 2005, interest in digital 3-D stereoscopic projection led to a new willingness on the part of theaters to co-operate in installing 2K stereo installations to show Disney's Chicken Little in 3-D film. Six more digital 3-D movies were released in 2006 and 2007 (including Beowulf, Monster House and Meet the Robinsons). The technology combines a single digital projector fitted with either a polarizing filter (for use with polarized glasses and silver screens), a filter wheel or an emitter for LCD glasses. RealD uses a "ZScreen" for polarisation and MasterImage uses a filter wheel that changes the polarity of projector's light output several times per second to alternate quickly the left-and-right-eye views. Another system that uses a filter wheel is Dolby 3D. The wheel changes the wavelengths of the colours being displayed, and tinted glasses filter these changes so the incorrect wavelength cannot enter the wrong eye. XpanD makes use of an external emitter that sends a signal to the 3D glasses to block out the wrong image from the wrong eye.
Digital distribution of movies has the potential to save money for film distributors. To print an 80-minute feature film can cost US$1,500 to $2,500, so making thousands of prints for a wide-release movie can cost millions of dollars. In contrast, at the maximum 250 megabit-per-second data rate (as defined by DCI for digital cinema), a feature-length movie can be stored on an off-the-shelf 300 GB hard drive for $50 and a broad release of 4000 'digital prints' might cost $200,000. In addition hard drives can be returned to distributors for reuse. With several hundred movies distributed every year, the industry saves billions of dollars. The digital-cinema roll-out was stalled by the slow pace at which exhibitors acquired digital projectors, since the savings would be seen not by themselves but by distribution companies. The Virtual Print Fee model was created to address this by passing some of the saving on to the cinemas. As a consequence of the rapid conversion to digital projection, the number of theatrical releases exhibited on film is dwindling. As of 4 May 2014, 37,711 screens (out of a total of 40,048 screens) in the United States have been converted to digital, 3,013 screens in Canada have been converted, and 79,043 screens internationally have been converted.
A number of high-profile film directors, including Christopher Nolan, Paul Thomas Anderson, David O. Russell and Quentin Tarantino have publicly criticized digital cinema and advocated the use of film and film prints. Most famously, Tarantino has suggested he may retire because, though he can still shoot on film, because of the rapid conversion to digital, he cannot project from 35 mm prints in the majority of American cinemas. Steven Spielberg has stated that though digital projection produces a much better image than film if originally shot in digital, it is "inferior" when it has been converted to digital. He attempted at one stage to release Indiana Jones and the Kingdom of the Crystal Skull solely on film. Paul Thomas Anderson recently was able to create 70-mm film prints for his film The Master.
The projectors used for celluloid film were largely the same technology as when film/movies were invented over 100 years ago. The evolutions of adding sound and wide screen could largely be accommodated by bolting on sound decoders, and changing lenses. This well proven and understood technology had several advantages 1) The life of a mechanical projector of around 35 years 2) a mean time between failures (MTBF) of 15 years and 3) an average repair time of 15 minutes (often done by the projectionist). On the other hand, digital projectors are around 10 times more expensive, have a much shorter life expectancy due to the developing technology (already technology has moved from 2K to 4K) so the pace of obsolescence is higher. The MTBF has not yet been established, but the ability for the projectionist to effect a quick repair is gone.
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CinemaScope was sensationally popular. Audiences fell in love with the bigger, wider images on theater screens. Many more movies were rushed into production using the format, and other major film studios licensed the process from Fox for their own movies.
Some studios, such as Sony or Warner Bros., are usually pretty good about preserving the precise 2.40:1 aspect ratio of modern movies. Others, like Fox, may be hit-or-miss from title to title, even on recently produced films.
In the 1950s, TV became ever more popular, and film studios got nervous. Some predicted the death of cinema, and it seemed like something had to be done to drag punters back towards the silver screen. Enter (through a very accommodating doorway) widescreen.
"Okay, so here's your reference. Today most digital projectors out there are around 1800-2000:1 [contrast ratio], or in that range. IMAX, through what we're doing today [in 2013], is at around 2500-2800:1, so we're higher than everybody else. IMAX projection film is in and around - you know, there are always variables that play into how well the system has been set up - the 4000:1 range, give or take. IMAX laser is going to be double that, at around 8000:1.
Added explanations of field count values for ProRes. Added display dimensions of HD source to accommodate video formats that use non-square pixels, for example, in broadcast dimensions. Added Audio Description (AD) requirements for film. Clarified music video screen capture image.
Unlike most people approaching middle age, Blade Runner can confidently say it's 35 years old and has never looked better. That's something it can thank the powers that be for, as studios haven't been shy in giving older films the 4K HDR treatment for their Ultra HD Blu-ray reissues.
4K video resolution is high-definition (HD) video that has four times the resolution of 1080p HD video. There are two standard resolutions for 4K video. The Digital Cinema Initiatives standard for 4K resolution in the film and video production industry is 4096x2160 pixels. The 4K resolution standard for television and monitors is 3840x2160 pixels.
4K resolution is the generic term for display devices or content having horizontal resolution on the order of 4,000 pixels. Several 4K resolutions exist in the fields of digital television and digital cinematography. In the movie projection industry, Digital Cinema Initiatives (DCI) is the dominant 4K standard. 2b1af7f3a8