Digital Picture Exchange (DPX) is a common

file format A file format is a standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary or free. Some file formats ...

for

digital intermediate Digital intermediate (typically abbreviated DI) is a motion picture finishing process which classically involves digitizing a motion picture and manipulating the color and other image characteristics. Definition and overview A digital intermediate ...

and

visual effects Visual effects (sometimes abbreviated VFX) is the process by which imagery is created or manipulated outside the context of a live-action shot in filmmaking and video production. The integration of live-action footage and other live-action foota ...

work and is a SMPTE standard (ST 268-1:2014). The file format is most commonly used to represent the

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

of each colour channel of a scanned negative film in an uncompressed " logarithmic" image where the

gamma Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter re ...

of the original camera negative is preserved as taken by a film scanner. For this reason, DPX is the worldwide-chosen format for still frames storage in most digital intermediate post-production facilities and film labs. Other common video formats are supported as well (see below), from video to purely digital ones, making DPX a file format suitable for almost any raster digital imaging applications. DPX provides, in fact, a great deal of flexibility in storing colour information, colour spaces and colour planes for exchange between production facilities. Multiple forms of packing and alignment are possible. The DPX specification allows for a wide variety of metadata to further clarify information stored (and storable) within each file. The DPX file format was originally derived from the

Kodak The Eastman Kodak Company (referred to simply as Kodak ) is an American public company that produces various products related to its historic basis in analogue photography. The company is headquartered in Rochester, New York, and is incorpor ...

Cineon open file format (.cin file extension) used for digital images generated by Kodak's original film scanner. The original DPX (version 1.0) specifications are part of SMPTE 268M-1994. The specification was later improved and published by SMPTE as ANSI/SMPTE 268M-2003. Academy Density Exchange (ADX) support for the

Academy Color Encoding System The Academy Color Encoding System (ACES) is a color image encoding system created under the auspices of the Academy of Motion Picture Arts and Sciences. ACES allows for a fully encompassing color accurate workflow, with "seamless interchange of ...

are added in the current version of the standard SMPTE ST 268-1:2014. Extensions for

high-dynamic-range video High-dynamic-range television (HDR or HDR-TV) is a technology that improves the quality of display signals. It is contrasted with the retroactively-named standard dynamic range (SDR). HDR changes the way the luminance and colors of videos and ...

and wide color gamut are standardized in SMPTE ST 268-2:2018.

Metadata and standard flexibility

SMPTE specifications dictate a mild number of compulsory metadata, like image resolution,

color space A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of colorwhether such representation entails an analog or a digital represent ...

details (channel depth, colorimetric metric, etc.), number of planes/subimages, as well as original filename and creation date/time, creator's name, project name,

copyright A copyright is a type of intellectual property that gives its owner the exclusive right to copy, distribute, adapt, display, and perform a creative work, usually for a limited time. The creative work may be in a literary, artistic, education ...

information, and so on. Furthermore, a couple of industry-specific metadata areas are present: Motion-Picture and Television ones. They are either used only if the picture has enough embedded information relevant to that specific industry, otherwise are left "empty". For example, Motion-Picture-specific metadata includes perforation-exact

film A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...

KeyKode (if the image comes from a film scan), camera shutter angle, slate information and frame positioning within a frame sequence. On the other side, Television metadata includes full SMPTE time code, video overscan and field information, and signal/colour level information. A third, variable-size metadata area, which is user-definable, exists. Third-party applications/software occasionally use this area to store additional information; for example, when the DPX stores images with technical specifications far away from the original standard (like pictures coded in the CIE '' XYZ'' color space, or

Bayer Bayer AG (, commonly pronounced ; ) is a German multinational corporation, multinational pharmaceutical and biotechnology company and one of the largest pharmaceutical companies in the world. Headquartered in Leverkusen, Bayer's areas of busi ...

-patterned raw frames from specific digital cameras like the Arriflex D-21). SMPTE ST 268-2:2018 defines a standards-based metadata section that supports

Extensible Metadata Platform The Extensible Metadata Platform (XMP) is an ISO standard, originally created by Adobe Systems Inc., for the creation, processing and interchange of standardized and custom metadata for digital documents and data sets. XMP standardizes a data ...

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...

, and KLV metadata representations.

Support

XnView can read FFmpeg pix_fmt=abgr DPX images. ImageMagick supports DPX. The C++ source of a DPX library is available. DjV, and vooya support DPX sequences.

References

{{SMPTE standards Graphics file formats SMPTE standards

Metadata and standard flexibility

Support

See also

References