Doug Kerr
Well-known member
Greetings,
Over the years, various matters of technology and technique have flowed back and forth between the fields of "still photography" and "cinematography". The same is true for the fields of "motion picture sound" and "sound recording".
An interesting example of the adoption of technology generally associated with still photography into the new realm of digital cinematography (which term implies work that is different, although not in any clear way, from the fields of "television" and "video") is a set of technical standards for the distribution of motion pictures in digital form to theaters with digital projection facilities.
The centerpiece of this structure is an overall architectural standard developed by Digital Cinema Initiatives, LLC (DCI), a consortium of six major motion picture studios, each with exhibition arms. (Metro-Goldwyn-Mayer had been an original member, but withdrew shortly before the first standard was issued - I do not know the back story there.)
Although the DCI standard is quite detailed, there are nevertheless numerous further details covered by a substantial suite of standards from SMPTE, The Society of Motion Picture and Television Engineers, and other cognizant standards bodies. Here, I will only discuss the DCI standard itself, and only its most prominent portions of its "picture" aspect.
To me, the fascinating thing about the DCI standard is that it involves numerous technical concepts with which we, as digital still camera enthusiasts, are familiar, but many of them in wholly unexpected ways.
Here we go.
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Image format
The basic DCI standard provides for two basic "format size families", whose maximum pixel dimensions are:
• 4096 x 2160 px (the "4k" family) [The family designation means that the maximum format width is in the vicinity of 4Kipx: 4096 pixels.]
• 2048 x 1080 px (the "2k" family)
Four important specific formats exactly mimic image aspect ratios of the two common contemporary film distribution formats:
• 3996 x 2160 px (4k version), 1998 x 1080 px (2 k version), aspect ratio 1.85:1. These are called the "flat" formats, a term carried from film distribution, where it means (through some strange logic) that the image is on the film in its final aspect ratio, not "squeezed". This is the format used for a number of years for most "sort-of-wide screen" films.
• 4096 x 1716 px (4k version), 2048 x 858 px (2 k version), aspect ratio 2.39:1. These are called the "scope" formats, a term carried from film distribution, where it means (by reference to "Cinemascope", an important format of this genre) that the image is on the film "squeezed" such that it must be horizontally expanded, by a factor of 2, in projection to attain the actual viewed aspect ratio. This is the format used for a number of years for most "seriously wide screen" films.
By the way, the pixels are "square" (same pitch along each axis). There is no "squeezing" implied by the digital "scope" formats.
There is no concept of "progressive" vs. "interlaced", a notion that should really never have entered into the matter of digital video at all. (But don't get me started on that here!) If one must draw the comparison, we could say that the DCI formats are all "progressive" formats.
Frame rate
Two frame rates are possible for these formats, 24 f/s and 48 f/s. The 48 f/s rate is only applicable to the 2k forms of the formats.
[To be continued in part 2.]
Over the years, various matters of technology and technique have flowed back and forth between the fields of "still photography" and "cinematography". The same is true for the fields of "motion picture sound" and "sound recording".
An interesting example of the adoption of technology generally associated with still photography into the new realm of digital cinematography (which term implies work that is different, although not in any clear way, from the fields of "television" and "video") is a set of technical standards for the distribution of motion pictures in digital form to theaters with digital projection facilities.
The centerpiece of this structure is an overall architectural standard developed by Digital Cinema Initiatives, LLC (DCI), a consortium of six major motion picture studios, each with exhibition arms. (Metro-Goldwyn-Mayer had been an original member, but withdrew shortly before the first standard was issued - I do not know the back story there.)
Although the DCI standard is quite detailed, there are nevertheless numerous further details covered by a substantial suite of standards from SMPTE, The Society of Motion Picture and Television Engineers, and other cognizant standards bodies. Here, I will only discuss the DCI standard itself, and only its most prominent portions of its "picture" aspect.
To me, the fascinating thing about the DCI standard is that it involves numerous technical concepts with which we, as digital still camera enthusiasts, are familiar, but many of them in wholly unexpected ways.
Here we go.
*************
Image format
The basic DCI standard provides for two basic "format size families", whose maximum pixel dimensions are:
• 4096 x 2160 px (the "4k" family) [The family designation means that the maximum format width is in the vicinity of 4Kipx: 4096 pixels.]
• 2048 x 1080 px (the "2k" family)
Four important specific formats exactly mimic image aspect ratios of the two common contemporary film distribution formats:
• 3996 x 2160 px (4k version), 1998 x 1080 px (2 k version), aspect ratio 1.85:1. These are called the "flat" formats, a term carried from film distribution, where it means (through some strange logic) that the image is on the film in its final aspect ratio, not "squeezed". This is the format used for a number of years for most "sort-of-wide screen" films.
• 4096 x 1716 px (4k version), 2048 x 858 px (2 k version), aspect ratio 2.39:1. These are called the "scope" formats, a term carried from film distribution, where it means (by reference to "Cinemascope", an important format of this genre) that the image is on the film "squeezed" such that it must be horizontally expanded, by a factor of 2, in projection to attain the actual viewed aspect ratio. This is the format used for a number of years for most "seriously wide screen" films.
By the way, the pixels are "square" (same pitch along each axis). There is no "squeezing" implied by the digital "scope" formats.
There is no concept of "progressive" vs. "interlaced", a notion that should really never have entered into the matter of digital video at all. (But don't get me started on that here!) If one must draw the comparison, we could say that the DCI formats are all "progressive" formats.
Frame rate
Two frame rates are possible for these formats, 24 f/s and 48 f/s. The 48 f/s rate is only applicable to the 2k forms of the formats.
[To be continued in part 2.]