Instruction manual

C-2
2K Color: More Like Film than Video
2K images, like SD and HD images, can come in 8 bit, 10 bit, 12 bit, 16 bit, and other
sizes. But most commonly, 2K files are written in a 10 bit Log RGB or RGB format.
This provides for 1024 gradations of a given color in three equivalent colors of red,
green and blue. By using RGB, 2K data can emulate, to some extent, film—which
achieves its color reproduction via red, green and blue layers of emulsion.
The actual 2K image sizes of 2048x1556 and 2048x1080 are usually written in two
similar, but slightly differing, file formats: Cineon or DPX (Digital Picture Exchange
format). The Cineon file format traces it's roots back to one of the earliest “film as
digital” devices, the Kodak Cineon. The Kodak Cineon, introduced in 1992, was a
scanner that took film images and translated them into digital data. Today many devices
from a number of manufacturers allow for such a process.
Since files bearing the .cin extension were always related to film, they tend to always be
in Log RGB. Log RGB is a color scheme designed to best approximate the
characteristics of film emulsion in a digital environment. An easy analogy is this: Log
RGB is like a “digital film negative” while linear RGB (usually just referred to as RGB) is
like a “digital film positive.” To transform a log RGB image into a “positive”, Look Up
Tables (LUTs) can be applied to the image so that before, during or after processing the
raw image can be seen as it would be if it were a finished product.
As already mentioned, Cineon files are not the only file format that can be used to house
the 2K data. DPX (Digital Picture Exchange) is quickly becoming the standard since
being defined by SMPTE. Like files bearing the .cin extension, files bearing the .dpx
extension can be Log RGB, but they can also be linear RGB.
Cineon and DPX files at full size, 2048x1556 and full 10 bit quality tend to exist as
individual frames that occupy 12.2 MB of data. At 12.2 MB/sec., data rates for a second
of video climb to 291.5 MB/sec. By comparison, the highest quality HD video images
rarely exceed 200MB/sec. and most HD formats use only a little over 100MB/sec.
Furthermore, HD material is usually somewhat compressed in order to be recorded
onto tape formats, whereas the 2K data can achieve an uncompressed status having
never had to be recorded onto a tape, but instead directly recorded onto a harddrive.
If the first major advantage of working with 2K images is their size, then the second
advantage is their handling of color. A 2K color scheme can be used that more closely
emulates films properties than video. Furthermore, this color information need not be
compressed due to the limitations of tape recording, but rather the data can be dealt
with as uncompressed.
The Source of 2K Data: Scanning, Telecine and Digital Cameras
Until recently, the only way to acquire a 2K image was to shoot on 35mm film and then
scan the original camera negative (OCN). To be fair, most 2K data is still generated in
this method since film is still seen as the de facto medium for recording moving images
for projection at the highest possible resolution. 2K scanning has persisted as the solitary
method of creating 2K data until recently when a handful of telecine machines have
come on the market that can move data at 2K resolution.