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#1032: spot colours defined in Lab keep their Lab values

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A .ai or PDF whose spot colours are defined in Lab opened them wrong:
- the PDF part gives such an ink an ICC Lab profile as its alternate
  space ([/ICCBased profile], 3 components), which was read as RGB, so
  the Lab values were clamped into wildly wrong colours (PANTONE 249 C
  came in yellow). A profile whose Alternate is [/Lab ...], or whose
  header names the Lab data colour space, is now read as Lab;
- the editing data writes them as `c m y k L a b (name) tint 2 Xx`,
  type 2 being Lab, and only the CMYK equivalent was read. Type 2 now
  gives the Lab colour, in the swatches and on the art.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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bflatastic
2026-10-11 07:06:05 +07:00
co-authored by Claude Opus 5.5
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# File format parity
> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-10 · **Change:** major (first checklist, from the `FORMATS` table and Illustrator 2026's documented formats) · **Target:** Adobe Illustrator 2026 (30.x)
> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-11 · **Change:** minor (Lab spot colours in `.ai` and PDF, #1032) · **Target:** Adobe Illustrator 2026 (30.x)
Every format Illustrator opens, places, saves or exports, against VectorCraft's format table (`FORMATS`,
`OPEN_EXTS`, `PLACE_EXTS` in `crates/engine/src/cmd/fileio/mod.rs`). Illustrator's list comes from its public
@@ -44,7 +44,7 @@ private editing data. VectorCraft:
### Illustrator's private editing data
the app's own editing copy of a file (an EPS after its `%%EOF`, a `.ai`'s `AIPrivateData` streams, Zstandard or zlib, the EPS's in ASCII85) is not documented as a whole. VectorCraft reads its structure: layers and sublayers (names, order, visibility, lock, printing, preview, dimming, colour), groups as they were nested, compound paths, clipping groups and layer clipping, object names, hidden and locked objects, fills and strokes (grey, CMYK, RGB, named and spot colours, global process colours as global swatches at their tint), linear and radial gradients, pattern fills with their patterns as pattern swatches (#1025), opacity, blend modes, isolation and knockout, embedded images with their alpha channel, guides, and every artboard where it is. An object with several fills or strokes, effects or a brush comes in as its drawn look (a group named after it). Type is made from the file's text document, whole and editable, shown or not: point type, area type (a story in several frames as threaded type) and type on a path, with its characters, fonts, size, leading, tracking, scaling, baseline shift, fill and stroke (grey, RGB or CMYK), alignment, indents and paragraph spacing; the page's drawing of it (often in pieces) is left out. Where the text document can't say (a frame of another kind, or a document that doesn't agree with the page), type that shows comes from the page into its text object's place (no group around it), and hidden type is left out with a note. Kerning, underline and the other character and paragraph options aren't read yet. A `.ai` saved without PDF compatibility (a placeholder page) opens from its editing data alone, its point type, area type and type on a path made from the text document. Symbols, pattern fills whose pattern it can't read, placed files and anything else it doesn't read make the file come in as its page (on a layer that doesn't show, they are left out of that layer), with a warning saying what. The layers' art is also compared with the page (by lightness, so colours written as their CMYK equivalents compare alike, and by whether a pixel is inked at all); the page is used when they differ by more than 5%, where one draws an object the other doesn't (away from type, whose lines may be laid out afresh), and when an EPS whose page is its art's box has art printed outside it (#735). `textAs: "outlines"` opens a `.ai` whose type shows from its PDF part, which has the outlines; `editingData: false` opens any of them as its page or PDF part only, for print pipelines (#735). A file whose import left something out (hidden text, art or layers) is never written over by an export or Save As to its own path unless `acknowledgeLoss: true` (`convert --replace-lossy`), so the original keeps what the document lacks. Where a `.ai` can't be read that way (or its layers are turned off in the import options), we read its PDF-compatible part, so Illustrator-only live objects arrive as appearance, and plain groups arrive ungrouped: that part draws each object on its own and marks only layers, clipping groups and groups with opacity, blending or a mask (those come back). Art outside the artboards isn't in that part at all (Illustrator's PDF part leaves it out), so it doesn't open; the import says so in a note (#472). That part also has no paragraphs: area type is written line by line, and comes back as area type only where its font is installed and lays the lines out with the same breaks, else as a point type object per line (#508). Art off the page that a PDF does draw opens on the pasteboard.
the app's own editing copy of a file (an EPS after its `%%EOF`, a `.ai`'s `AIPrivateData` streams, Zstandard or zlib, the EPS's in ASCII85) is not documented as a whole. VectorCraft reads its structure: layers and sublayers (names, order, visibility, lock, printing, preview, dimming, colour), groups as they were nested, compound paths, clipping groups and layer clipping, object names, hidden and locked objects, fills and strokes (grey, CMYK, RGB, named and spot colours, spot colours defined in Lab with their Lab values (#1032), global process colours as global swatches at their tint), linear and radial gradients, pattern fills with their patterns as pattern swatches (#1025), opacity, blend modes, isolation and knockout, embedded images with their alpha channel, guides, and every artboard where it is. An object with several fills or strokes, effects or a brush comes in as its drawn look (a group named after it). Type is made from the file's text document, whole and editable, shown or not: point type, area type (a story in several frames as threaded type) and type on a path, with its characters, fonts, size, leading, tracking, scaling, baseline shift, fill and stroke (grey, RGB or CMYK), alignment, indents and paragraph spacing; the page's drawing of it (often in pieces) is left out. Where the text document can't say (a frame of another kind, or a document that doesn't agree with the page), type that shows comes from the page into its text object's place (no group around it), and hidden type is left out with a note. Kerning, underline and the other character and paragraph options aren't read yet. A `.ai` saved without PDF compatibility (a placeholder page) opens from its editing data alone, its point type, area type and type on a path made from the text document. Symbols, pattern fills whose pattern it can't read, placed files and anything else it doesn't read make the file come in as its page (on a layer that doesn't show, they are left out of that layer), with a warning saying what. The layers' art is also compared with the page (by lightness, so colours written as their CMYK equivalents compare alike, and by whether a pixel is inked at all); the page is used when they differ by more than 5%, where one draws an object the other doesn't (away from type, whose lines may be laid out afresh), and when an EPS whose page is its art's box has art printed outside it (#735). `textAs: "outlines"` opens a `.ai` whose type shows from its PDF part, which has the outlines; `editingData: false` opens any of them as its page or PDF part only, for print pipelines (#735). A file whose import left something out (hidden text, art or layers) is never written over by an export or Save As to its own path unless `acknowledgeLoss: true` (`convert --replace-lossy`), so the original keeps what the document lacks. Where a `.ai` can't be read that way (or its layers are turned off in the import options), we read its PDF-compatible part, so Illustrator-only live objects arrive as appearance, and plain groups arrive ungrouped: that part draws each object on its own and marks only layers, clipping groups and groups with opacity, blending or a mask (those come back). Art outside the artboards isn't in that part at all (Illustrator's PDF part leaves it out), so it doesn't open; the import says so in a note (#472). That part also has no paragraphs: area type is written line by line, and comes back as area type only where its font is installed and lays the lines out with the same breaks, else as a point type object per line (#508). Art off the page that a PDF does draw opens on the pasteboard.
## Format by format
@@ -80,6 +80,7 @@ the app's own editing copy of a file (an EPS after its `%%EOF`, a `.ai`'s `AIPri
| Date | Change | Summary |
|---|---|---|
| 2026-10-11 | minor | Spot colours defined in Lab keep their Lab values, from the editing data and from a PDF part whose ink alternate is an ICC Lab profile (#1032) |
| 2026-10-11 | minor | `.ai` in PostScript form opens through its layers, also without its prolog (#1027) |
| 2026-10-11 | minor | `.ai` editing data: global process colours and pattern fills read, so they no longer drop sublayers (#1025) |
| 2026-10-10 | major | First checklist; moved the `.ai` editing-data scope from the ROADMAP's "Out of scope" here; added the user-reported `.ai` failures |