pdf-association
Clarify restrictions for uncoloured (shape-only) Type 3 glyphs
Glyphs in a Type 3 font may contain their own colour descriptions via the d0 operator or specify only shape via the d1 operator. While transparency was not mentioned as restricted in ISO 32000-1, ISO 32000-2 clarifies this in the d1 description: "...set the colour (or other colour-related parameters including transparency) in the graphics state"
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Editorial problem in Table 111: transparency was added in a single location, while others talk only about colour: d0 description: "...specifies both its shape and colour" d1 description: "...specifies only shape, not colour", "Its colour shall be determined..." "...painted with the current colour." Suggestion: consolidate by mentioning both colour and transparency in all relevant locations.
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Technical problem with 8.6.8, bullet item "All of the following entries, if present in the graphics state parameter dictionary of a gs operator shall be ignored": In the general description in Table 111 we learned that transparency should not be used, but the detailed list in 8.6.8 doesn't mention transparency entries in the graphics state dictionary. Suggestion: in the list "TR, BG UCR..." add "SMask, CA, ca, AIS".
Related: in the recent ISO TC 171 SC 2 WG 8 meeting, a new PDF extension document was proposed:
ISO/NP PDTS, Document management - Clarification for initial graphic state in ISO 32000-2 RESOLUTION 2021-03-WG8 - Virtual Meeting May 2021 - ISO/TC171/SC2 agreed that WG8 will prepare an NP to propose the work on the preparation of an ISO Technical Specification on the clarification of initial graphic state in ISO 32000-2 by June 17, 2021. The NP will be submitted to P-members by vote via the ISO Committee Balloting portal by June 21, 2021. The project co-leaders for this project will be Bert Van Kerckhove and Peter Wyatt.
Issues with d0/d1 had been identified from Bert's previous work.
Flagging as "parked" as ISO TC 171 SC 2 WG 8 has a new work item which will hopefully resolve this issue: "ISO/NP PDTS 6912, Document management - Clarification for initial graphic state in ISO 32000-2"
The initial graphics state discussions so far have only addressed patterns and soft masks; there's nothing in the current text around T3 fonts. I'd rather keep it that way to maximise the likelihood of delivering something definitive in a sensible time!
