Overview
ISO 12640-3:2022 - Graphic technology - Prepress digital data exchange - Part 3: CIELAB standard colour image data (CIELAB/SCID) - defines a standardized set of large-gamut test images encoded as 16‑bit CIELAB. The dataset is intended for objective and subjective evaluation of image quality across coding, image processing (transformations, compression/decompression), display and printing. Images are referenced to CIE illuminant D50 and supplied in industry-standard file formats to support reproducible testing of colour management workflows, printers and output systems.
Keywords: ISO 12640-3, CIELAB, standard colour image data, prepress digital data exchange, D50, 16-bit CIELAB, colour gamut, TIFF, PDF, colour management.
Key topics and requirements
- Data encoding and format: Natural images are provided as 16‑bit per channel CIELAB (L, a, b) pixel-interleaved data with origin at the upper-left, organized by rows. Image files follow TIFF conventions (BitsPerSample = 16,16,16); colour charts and vignettes are supplied in PDF.
- Reference gamut and viewing: Images are designed to cover a large reference colour gamut relevant to printing and photographic outputs; the reference gamut derivation and D50 referencing are documented in the standard (Annex B).
- Image set composition: The dataset includes natural scenes (diverse subject matter including flesh tones, highlights/shadows, near-neutrals) plus synthetic colour charts and vignettes to explore gamut boundaries and neutral subtleties.
- Normative and informative annexes: Guidance for use, TIFF header examples, checksum data, histogram/gamut plotting, and CIELAB values for charts are included to support implementation and verification.
- Compatibility guidance: The standard complements other parts of ISO 12640 (Part 1, Part 2) and references related colour-encoding standards (e.g., sRGB/IEC 61966-2-1) and ISO 12639 TIFF conventions.
Applications and who uses it
- Colour management specialists and ICC profile creators - validate rendering and profile transforms across wide gamuts.
- Printer manufacturers and print labs - evaluate print reproduction fidelity and gamut handling.
- Imaging software developers - test compression, colour transforms, and algorithms with high-bit-depth, device-independent data.
- QA/test laboratories and researchers - run reproducible comparisons of device performance, compression artifacts, and display-to-print workflows.
- Photographers and prepress professionals - assess end-to-end reproduction and refine production pipelines.
Related standards
ISO 12640-3:2022 is a practical resource for anyone needing reproducible, device-independent test images in CIELAB for research, development, and quality assurance of modern colour workflows.
