ISO 18620:2016 PDF

Overview

ISO 18620:2016 - Graphic technology - Prepress data exchange - Tone adjustment curves exchange - defines a simple, extensible XML format for exchanging tone adjustment curves (also called transfer functions or plate curves) between prepress and print-production applications. The standard targets interoperability between systems such as colour management, press calibration, and raster image processors (RIPs), enabling consistent transfer of printing-plate and separation adjustment data.

Key topics and requirements

• XML-based format: Files are XML documents (first line <?xml version="1.0" encoding="UTF-8"?>) and use a dedicated namespace: http://www.npes.org/schema/[ISO18620](/search?q=ISO18620)/.
• TransferCurveSet: A single root element that can include metadata (Creator, CreationDate, OperatorName, PressName, MediaName, Side) and one or more TransferCurve elements.
• TransferCurve structure:
  • Attribute Separation (e.g., Cyan, Magenta, Yellow, Black, Default, or stakeholder-agreed names).
  • Curve value is a whitespace-separated list of XY coordinate pairs in the range 0.0–1.0 (x = input tint, y = mapped output), with mandatory end points at 0,0 and 1,1.
  • Curve points must be ordered by X; curves are either increasing or decreasing (monotonic) to avoid artifacts.
• Defaults and per-separation overrides: A TransferCurve with Separation="Default" applies where no specific separation entry exists.
• Extensibility: Vendor-specific elements/attributes are allowed in separate namespaces; compliant readers must safely ignore unknown vendor extensions.
• Interpretation: TransferCurves are applied to document separations during rendering or after rendering but prior to plate-making/printing.
• Examples: The standard includes example curves (e.g., simple cutbacks, flexo “bump” discontinuities) to illustrate common practices.

Applications and users

ISO 18620 is practical for organizations that need to exchange or centralize tone-adjustment and calibration data:

• RIP developers and colour management software vendors implementing consistent transfer functions.
• Prepress providers and plate-making services sharing plate calibration data across tools.
• Print shops, press operators and calibration teams for standardizing press adjustments.
• Print certification and QA vendors that must support multiple vendor formats - this standard reduces format fragmentation.

Keywords: ISO 18620:2016, tone adjustment curves, transfer curves, prepress data exchange, colour management, press calibration, raster image processor, XML schema.

Related standards

• Namespaces in XML (W3C)
• XML Schema Part 2: Datatypes (W3C)
• ICC CMYK Characterisation Data registry (referenced for printing condition identifiers)