ANSI/NIST-ITL 1-2011 - NIST Visual Image Processing Group ...

ANSI/NIST-ITL 1-2011Data Format for the Interchange of Biometric and Forensic Informationformat. However, in cases where an alternative encoding is used, the sendingand receiving parties shall document encoding rules and assumptions. Rules foradditional encodings may be posted at www.biometrics.nist.gov/standard with theconsensus approval of the canvassees.4 Transmitted data conventionsThe following conventions apply to all encodings of the ANSI/NIST-ITL 1-2011standard.4.1 Friction Ridge RepresentationRidges in friction ridge images shall be represented as “dark ridges” on a lightbackground, in either grayscale or binary image data.4.2 Byte and bit orderingEach information item, subfield, field, and record shall contain one or more bytesof data. Within a file, the order for transmission of both the ASCII and the binaryrepresentations of bytes shall be most significant byte first and least significantbyte last otherwise referred to as Big-Endian format. Within a byte, the order oftransmission shall be the most significant bit first and the least significant bit last.Figure 1 illustrates the order of transmission of the bytes and bits.Brad Wing 6/25/10 11:52 AMComment: Explanation of encoding content.Note that this is now the extent of encodingreferences in the document itself. “Traditional”is used to refer to the encoding used in theoriginal versions of the standard (up through2007) and included here by reference. In thebody of the standard, short names and longnames have been eliminated, so as to furtherensure that the standard is content based.Short-tag encoding is not specificallymentioned. The canvassees will vote onwhether to post encoding rules for that formatas an action separate from the content of thestandard itself.Brad Wing 6/19/10 5:07 PMComment: Note reordering within this sectionBrad Wing 6/19/10 5:07 PMComment: Introductory sentence added.Figure 1 Byte and bit ordering4.3 Grayscale dataDepending on the record type, grayscale image data may be transmitted in eithercompressed or uncompressed form. The transmission of uncompressed4DRAFT 2