Formats/DPX

From VFXPedia

Format Extension

DPX files use the .DPX file extension.

  image.0001.dpx

Format Description

The Digital Moving Picture Exchange Bitmap (DPX) fileformat is quickly replacing Cineon as the standard digital image format used by the film industry. The DPX file format is essentially identical to the Cineon format with a more flexible header, which allows it to be used to store images from a wider variety of sources. Unlike Cineon which was a vendor standard promoted by Kodak, DPX format has the advantage of being an industry standard under SMPTE.

While Cineon files almost always contain logarithmic image data from a scanned or telecined film frame, DPX files are used to store images from a variety of sources, from film scanners, to digital video cameras, to HD video disk recorders. As a result, a DPX file may contain image data in 8 bit int, 16 bit int, 10 bit log, or several other color depths.

In theory a proper DPX file will specify the color depth and format of the data it contains in the header. eyeon Software's Fusion and other compositing applications will use that information to determine what color depth to process the image at, and whether to perform a log to lin conversion. In practice, the headers of many DPX files are written incorrectly, and will provide misleading information. For example, eyeon Support is often provided with examples of DPX files whose headers indicate 10 bit linear data, even though the contents are actually in 10 bit log color space.

A few free utilities are available that can inspect the contents of a DPX file's header:

 GraphicsMagick
 http://www.graphicsmagick.org/www/motion-picture.html
 
 RN_DPX
 http://www.rendernan.com/

For an overview of the structure of a DPX file, see the Cineon Image File Format Draft at http://www.cineon.com/ff_draft.php. To obtain the SMPTE specification, contact SMPTE directly at +1.914.761.1100 and ask for the specification ANSI/SMPTE 268M-1994, SMPTE Standard for File Format for Digital Moving-Picture Exchange (DPX), v 1.0, 18 February 1994.

Timecode Metadata and Fusion

If a DPX file has timecode embedded into the header of the file, Fusion 5 will display that information in Loader's "Time Code Offset" input (on the Comments tab), as well as in the popup tooltip from Loader's flow tile. The timecode will be displayed as either a frame count, SMPTE timecode, or in feet+frames format, according to the timecode settings in the View menu.