1. Taming unusual workflows with iccMAX Marti Maria Hewlett-Packard
November 3rd, 2014
Joseph B. Martin Conference Center at Harvard Medical School*
Boston, MA
*Note: Neither NPES nor ICC DevCon is affiliated with Harvard University, and neither NPES nor ICC DevCon is a Harvard University program or activity.

2. Agenda – What is this talk about
What you mean unusual color workflows?
Changing viewing conditions.
Measurement standards.
Special connection spaces.
Spectral matching.
Fluorescence

3. What you mean unusual color workflows?
Limitations in current ICC workflows

4. Limitations in current ICC workflows
What is in previous ICC specs?
Colorimetric connection spaces: XYZ or Lab
CIE 1931 Standard observer (2º)
D50 as white point
No flare, 0º/45º geometry (M1 of ISO 13655)
fixed viewing conditions (P2 of ISO 3664)
Ideal reflection print (V2) or reference medium (V4)
Maximum of 16 channels
The reference medium is defined as a hypothetical print on a substrate with a white having a neutral reflectance of 89 %, and a density range of 2, The viewing reference is a standard viewing booth conforming to ISO 3664 viewing condition P2, using the recommended 20 % surround reflectance. This is a graphics arts and photography print appraisal environment using D50 illumination at a level of 500 lx.

5. New features in iccMAX Just some, not all.
Colorimetric, Appearance, Spectral, Bi-Spectral and Material connection spaces
Arbitrary illuminants, geometry and observers.
Nonstandard viewing conditions.
Up to channels.

6. Some differences in iccMAX profiles
From the coder’s point of view

7. Compatibility  Backwards compatible
An iccMAX CMM will be completely backward- compatible and will recognize and correctly process V2 and V4 profiles. However, iccMAX profiles are not expected to be compatible with V4 CMMs.
ICC will seek to provide a reference implementation to help with iccMAX adoption.

8. Header changes for PCS extensions
PCS field defines PCS color space for A2Bx/B2Ax tags
If zero then no colorimetric PCS is used and no A2BX/B2AX tags should exist
A2Bx/B2Ax tags can also be of type multiProcessElementType
Colorimetric PCS can be other than D50 with 2 degree observer
XYZ values of illuminant must match illuminant and observer used
Spectral PCS fields added
Spectral PCS field defines color space for D2Bx/B2Dx tags
If zero and D2Bx/B2Dx tags exist then PCS field is used to define PCS
Spectral PCS range defines wavelength range
Bi-directional PCS range defines excitation range when bi-dir spectral color space is used

9. iccMAX new profile classes
Signature
Hex encoding
Input Device profile
‘scnr’
73636E72h
Display Device profile
‘mntr’
6D6E7472h
Output Device profile
‘prtr’ h
DeviceLink profile
‘link’
6C696E6Bh
ColorSpace profile
‘spac’ h
ColorEncoding profile
‘cenc‘
63656E63h
Abstract profile
‘abst’ h
NamedColor profile
‘nmcl’
6E6D636Ch
MaterialIdentification profile
‘mid ’
6D696420h
MaterialLink profile
‘mlnk’
6d766973h
MaterialVisualization profile
‘mvis’
Each class to cover a type of application. For example, Input profiles apply to devices such as digital cameras and scanners, Display apply to Monitors and Output apply to printers.
In addition to the three basic device profile classes, other additional colour processing profiles are defined.

10. iccMAX new base types (some)
icFloat16Number
IEEE 16 bit floating point
icFloat64Number
IEEE 64 bit floating point
spectralRange
Starting Wavelength (icFloat16Number)
Ending Wavelength (icFloat16Number)
Total number of steps including start and end.

11. iccMAX tag Structures and tag Arrays
Signature for structure type
List of Tags identified by signatures
Examples: brdfStruct, namedColorStruct, zeroTintStruct
Tag Array
Signature for array type
Ordered list of tags (identified by index)
Example: namedColorArray (contains one zeroTintStruct and one or more namedColorStructs)

12. Changing viewing conditions
“There are no facts, only interpretations.” ― Friedrich Nietzsche

13. The problem Example: ISO 3664:2000 (viewed independently )
Uses D65 for proofing
ISO 12646:2004 (directly compared to a hard copy)
As well as previous ICC specs, requires D50 as illuminant. Chromatic adaptation can be used across CHAD tag, but still the color matching is done as viewed under D50

14. iccMAX Profile Connection Conditions (PCC)
PCC information is required whenever PCS is NOT standard D50 using 2-degree observer
CMM becomes responsible for converting PCS data – not profile maker
Provides for interoperability to connect different viewing conditions
Provides flexibility for when and how conversions are made

15. iccMAX viewing conditions in 3 tags
spectralViewingConditions
Defines the spectral power distribution of the illuminant, colour matching functions (CMF) of the observer, and the lighting levels of the surround.
If different from the standard PCS:
customToStandardPCC (PCS  PCS)
Defines a transform that converts the from the custom viewing condition colorimetry to standard viewing condition colorimetry.
standardToCustomPCC (PCS  PCS)
Defines a transform that converts the from standard viewing condition colorimetry to the custom viewing condition.
Or use CMM default methods, maybe an appearance model.

16. Changing measurement standards
Not everything that counts can be counted, and not everything that can be counted counts - Albert Einstein, (attributed)

17. The problem
Example: The CIE defined two sets of color-matching functions for use as standard observers.
CIE 1931 Standard Colorimetric.
CIE 1964 Supplementary Standard Colorimetric.
The difference is based on the field of view used in the collection of the experimental data.
Which set of color-matching functions is more relevant for monitor calibration?
Calibrating a color monitor involves measuring color patches that are displayed on the screen of the monitor. The patches are clearly larger than a 4-degree field of view.
ICC Previous specs requires standard observer of 2º field of view

18. Profile Connection Conditions (PCC)
Header color space and spectral PCS metadata
measurementType records measurement conditions
spectralViewingConditionsTag defines a structure that spectrally specifies observer and illuminant
customToStandardPcsTag defines an MPE based tag to convert from custom PCS colorimetry to standard D50 / 2º observer colorimetry
standardToCustomPcsTag defines an MPE based tag to convert from standard D50 / 2º observer colorimetry to custom PCS colorimetry

19. Profile Connection Conditions (PCC)
A Sensor Adjustment Transform (SAT) transforms sensor excitations to sensor excitations independent of reason or method
A Chromatic Adaptation Transform (CAT) predicts sensor excitations of corresponding colors (based on adaptation of human observer) Predicts appearance constancy
A Material Adjustment Transform (MAT) predicts sensor excitations of an object for an observer/illuminant based on sensor excitations of the same object for a different observer/illuminant Predicts material constancy
CAT’s and MAT’s are both examples of SAT’s

20. Special connection spaces

21. Example: Gloss enhancer ink

22. HP DesignJet Z3200

23. Workflow The workflow should:
connect GE channels from input to output profile in some cases,
Default GE to zero in some cases (non glossy media)
Default GE to full in other cases (glossy with a special setting)

24. Gloss Enhancer Workflow
Input (embedded) profile
Output profile (for Glossy)
PCS (Lab)
GE channel to include ink-limit
GE channel
PCS (Lab)
PCS (Lab)
GE channel
PCS (Lab)

25. Material Connection Spaces (MCS)
A separate connection space defined by material channel identification for AToM0/MToA0/MToB0/MToS0 tags using a MCS signature field in the profile header.
If this field is zero then material connection is not defined.
MCS connection is performed by passing values for material channels between profiles that have identical Material Channel Type values (defined in the materialTypeArrayTag of both profiles).
The MCS subset requirements must be met before profiles can be linked.
Once these requirements are met the channels with a material type in the source profile that are not in the destination profile are ignored, and channels with material types in the destination profile that are not in the source profile are processed with the material value defined for the channel in the materialDefaultValuesTag or zero if this tag is not present.

26. Spectral matching

27. The problem Packaging printing Unexpected illuminants
Different printers / batchs
All placed together, side-by-side

28. General Colorimetric PCS Processing
Convert to XYZ colorimetry
Convert Spectral to XYZ colorimetry (using PCC)
Convert from Lab to XYZ
XYZ scaling for relative/absolute/BPC
Conversion of PCS colorimetry (using PCC)
Use source PCC customToStandardPcsTag
Use destination PCC standardToCustomPcsTag
Conversion to Lab (as needed)

29. Spectral PCS processing
To define the use of a spectrally based PCS, one of the spectral colour space signatures in Table 17 shall be used to encode the colour space implied by the spectralPCS field of the profile header.
These colour space signatures define both the colour space type as well as the number of channels associated with the colour space.
Therefore, the number of channels implied by the spectralPCS colour space signature shall match the number of channels indicated by the steps field(s) of the corresponding spectralRange structures in the profile header.
Spectral colour space type
None (PCS defined by PCS header field)
Reflectance spectra with N channels
Transmission spectra with N channels
Radiant (Emission) spectra with N channels
Bi-spectral Reflectance spectra with N total channels
Bi-spectral Reflectance using sparse matrix with N equivalent output channels

30. PCS Connection Support
From Lab
From XYZ
From Reflectance
From Transmissive
From Radiant/ Emission
From Fluorescence
To Lab
Yes
Using PCC
To XYZ
To Reflectance No
Extract PCC illuminant
Apply then extract PCC illuminant
To Transmissive
Use PCC illuminant
To Radiant / Emission
Apply PCC Illuminant
Apply PCC illuminant
To Fluorescence
Exact match

31. Fluorescence

32. The problem

33. The problem

34. Bi-Spectral Bispectral spectrophotometric instruments can make
colorimetric measurements taking into account the contribution of both the fluorescent and the reflected component to the total radiance of a sample.
This way the measurement becomes light-source independent and the full bispectral radiance factor can be obtained in a matrix form as a function of the excited wavelengths.

35. Bi-Spectral

36. Wrap-Up

37. Taming unusual workflows with iccMAX
Changing viewing conditions  PCC
Changes in measurement standards  PCC
Special connection spaces  MCS
Spectral matching  Spectral PCS.
Fluorescence  Bi-Spectral PCS

38. Taming unusual workflows with iccMAX
Thank you!
Taming unusual workflows with iccMAX