Overview
ISO/IEC 10918-6:2013 - "Information technology - Digital compression and coding of continuous‑tone still images: Application to printing systems - Part 6" defines a focused subset of the JPEG ecosystem for reliable interchange of JPEG images in printing workflows. It specifies how JPEG-encoded images (per Rec. ITU‑T T.81 | ISO/IEC 10918-1) should be interpreted, annotated and exchanged for print systems, with particular attention to colour encodings, metadata (ICC profiles), component ordering, supported frame types and application marker handling.
Keywords: ISO/IEC 10918-6:2013, JPEG for printing, ICC profile, CMYK, YCCK, RGB, JFIF, APP markers, colour management.
Key topics and technical requirements
- Supported image component counts and assumptions
- 1 component = grayscale (0 = black, 255 = white).
- 3 components = assumed RGB encoded as YCbCr unless overridden by an APP14 (Adobe) marker.
- 4 components = assumed CMYK (0,0,0,0 = white) unless APP14 indicates YCCK.
- Component ordering
- RGB (3): R, G, B.
- YCbCr (3): Y, Cb, Cr.
- CMYK (4): C, M, Y, K.
- YCCK (4): Y, Cb, Cr, K.
- SOF (Start of Frame) markers
- Only Baseline DCT (0xFFC0), Extended Sequential (0xFFC1), and Progressive DCT (0xFFC2) are allowed.
- Sample precision must be 8 bits; number of components must be 1, 3 or 4. DNL marker is not used.
- Application markers
- APP2 (0xFFE2) for embedding ICC profiles (concatenated if split across segments).
- APP14 (0xFFEE) (Adobe) used to indicate colour transform with transform flags:
- 0 = CMYK with complemented values or RGB (no transform).
- 1 = YCbCr (3-component).
- 2 = YCCK (4-component).
- Colour conversions
- RGB ↔ YCbCr conversions per ISO/IEC 10918-5 (Rec. ITU‑T T.871).
- YCCK derived from CMYK by converting CMY → YCbCr with channel substitution and complementing K.
Applications and who uses this standard
- Digital printing vendors, RIP developers and printer firmware implementers ensuring JPEG image interchangeability.
- Software developers and imaging libraries that encode/decode JPEG files targeted for print workflows.
- Colour management engineers integrating ICC profiles in printed output pipelines.
- Prepress and production environments requiring deterministic interpretation of CMYK, RGB, YCCK and embedded metadata.
Related standards
- ISO/IEC 10918-1 (Rec. ITU‑T T.81) - JPEG core
- ISO/IEC 10918-5 (Rec. ITU‑T T.871) - JPEG File Interchange Format (JFIF) and colour conversions
- ISO 15076-1 - ICC profile format (colour management)
- Rec. ITU‑R BT.601 - studio encoding parameters
This standard ensures predictable colour interpretation and metadata handling for JPEG images in printing systems, improving interoperability across printers, RIPs and imaging software.
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