Colour: ICC CMYK converts straight into the RGB profile, with black-point compensation

CMYK went to RGB through display sRGB: CMYK -> sRGB (clamped) -> working RGB.
Into a wider space (Wide Gamut RGB, the 1998 primaries) that clipped every
colour sRGB can't hold - CMYK cyan's red channel landed at 99 instead of 0 -
and the black-point compensation setting had no effect (moxcms leaves it
unimplemented). An ICC CMYK profile now converts directly into the RGB
profile: into its primaries with linear curves, where compensation is a
linear remap from the profile's black (found by sending black through the
profile and reading it back), then onto its own curves. The canvas uses the
same conversion into sRGB, so what shows is what an RGB export writes.

Checked against Ghostscript with the same profiles (relative colorimetric,
compensation on and off): exports into Wide Gamut RGB and the sRGB display
agree within 1 level in 255. The built-in CMYK spaces are unchanged (Generic
CMYK compensates in its own model).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ROADMAP.md

@@ -146,7 +146,7 @@ grade by behaviour against `plan/illustrator/`, not by whether a menu item exist
 - **Advanced art:** live Blends (steps/distance/smooth colour, editable spine, anchor-targeted Blend tool, faithful interpolation, knockout), Envelope Distort (warp/mesh/top object, Reset, full Envelope Options, mesh handles, Edit Contents; type, images, symbols, gradients, patterns and appearance distorted everywhere), Liquify tools with options and pen pressure, Puppet Warp with rotating pins, Perspective Grid with presets, movable planes and projected type (choosing a perspective tool shows the grid; Hide Grid hides it with the tool still chosen), Gradient Mesh, Shape Builder (stroke-only open paths and lines cut the regions they cross and enclose regions of their own; filled open paths count as closed; erase mode while Alt/Option is held: a minus pointer, red highlights of what will go, a click or drag deletes the regions touched, the pieces of open lines and the edges (outline pieces between the points where paths meet, opening their paths there) it passes over, one undo step, `shapeBuilder.merge {erase}` and `shapeBuilder.regions` edges over MCP), Live Paint (every path an edge, open lines included), Image Trace (12 presets, colour layers traced in parallel; a trace past two million anchor points or an image over 64 megapixels is refused with advice rather than running out of memory, and a selection too large to outline shows its bounds (#525); Object › Image Trace › Make and Make and Expand trace at once with the Default preset, #543; with an image selected the Control bar and the Properties panel show Image Trace, whose arrow traces with any preset, Mask (`object.maskImage`: a clipping path on the image's outline, selected so its handles crop), Crop Image and Embed or Unembed in place of Fill and Stroke; with an Image Trace object selected, its Preset (choosing another traces again), View, the Image Trace panel and Expand, plus Release in Properties; the five View modes (Tracing Result, with Outlines, Outlines, Outlines with Source Image, Source Image) redraw a trace on screen without tracing again, are saved with it and `imageTrace.setView` sets them, while exports and Expand keep the result; the panel's Advanced section is a header that stays open or closed as it was left (part of #641); Color mode's Palette: Limited, Full Tone (as many colours as the tones need, Less … More), Automatic (flat art with its own colours, else Full Tone; a heuristic) and Document Library (the most used colours of the document's swatches or a swatch library, filled with the swatch colours as they are), part of #641; Advanced › Create: Fills and/or Strokes, where lines up to the Stroke width trace as stroked centre lines (distance transform, thinning, a skeleton graph with spurs pruned, curve fitting; one width per line; without Fills, wider areas become stroked outlines), part of #641), pattern swatches with pattern editing mode, live Repeat (radial/grid/mirror).
 - **Paint and appearance (M3):**
   - **Swatches:** names follow the colour model and are unique; Swatch Options (process/spot, Global, Gray/RGB/HSB/CMYK/Web, live preview); editing a global or spot swatch recolours every linked fill, stroke and text run in one undo step; multi-select and delete with confirmation; New Swatch and New Color Group dialogs (a group from the selected artwork's colours); swatches in colour groups convert, separate and count like any other. The Swatches panel selects ranges and whole groups, has a find field, and drags swatches to reorder, regroup or paint art; Add Used Colors, Select All Unused, Merge, Ungroup and Sort by Kind; a CMYK document keeps applied colours in CMYK. Swatch libraries: nine generated colour libraries and five gradient libraries in a library panel, saved as `.vcswatches`, `.gpl` or CSS, and loaded from `.vcswatches`, `.gpl` and swatch exchange (`.ase`) files (RGB, CMYK, Lab and Gray; global, spot and process; groups). Tints of global and spot colours ("Name 40%") stay linked and separate as a percentage of their plate. Spot colours can be defined in Lab (Spot Colors options). A built-in [Registration] swatch prints on every plate.
-  - **Colour:** a Color Picker (colour field, H/S/B/R/G/B channel slider, HSB/RGB/Lab/CMYK fields, hex, web-only snapping, out-of-gamut correction); the Color panel follows each colour's own model and Alt-click paints the other proxy; proxies look through groups and show "?" for mixed paint; Invert, Complement, Apply Last Color (`,`) and Apply Last Gradient (`.`) keep the colour model; every paint command feeds the recent colours. The Color Guide has 21 harmony rules, Steps and Variation options and Limit to Library. Adjust Color Balance (its Global mode shifts tints) and Saturate preview live; Edit Colors and Recolor also reach meshes, images and patterns. Recolor Artwork has colour reduction, five recolour methods, presets, Limit to Library, a colour-wheel Edit tab and Edit Color Group; a local Color Themes panel saves five-colour themes. Fill/Stroke chips open swatch and mixer popovers (the Properties panel has the Control bar's Fill and Stroke chips, Stroke link and weight spinner, with nothing selected too), panels have Illustrator's Window menu keys (Align Shift+F7, Transform Shift+F8, Pathfinder Cmd+Shift+F9, Layers F7, Character Cmd+T…; every panel can be given one in Edit › Keyboard Shortcuts), and Eyedropper Options pick up and apply chosen attributes (Alt and Shift+Alt, image pixels). Fills and strokes can overprint (Attributes panel, Overprint Black options), and CMYK documents blend in inks on screen, in PDF and when flattening. Document Color Mode converts the art, symbols, pattern tiles and swatches through the colour settings: Gray stays Gray, RGB greys separate into four-colour greys and a rich black as Illustrator does, or go on the black plate only with `grays: "black"` (also for `document.open {colorMode}`).
+  - **Colour:** a Color Picker (colour field, H/S/B/R/G/B channel slider, HSB/RGB/Lab/CMYK fields, hex, web-only snapping, out-of-gamut correction); the Color panel follows each colour's own model and Alt-click paints the other proxy; proxies look through groups and show "?" for mixed paint; Invert, Complement, Apply Last Color (`,`) and Apply Last Gradient (`.`) keep the colour model; every paint command feeds the recent colours. The Color Guide has 21 harmony rules, Steps and Variation options and Limit to Library. Adjust Color Balance (its Global mode shifts tints) and Saturate preview live; Edit Colors and Recolor also reach meshes, images and patterns. Recolor Artwork has colour reduction, five recolour methods, presets, Limit to Library, a colour-wheel Edit tab and Edit Color Group; a local Color Themes panel saves five-colour themes. Fill/Stroke chips open swatch and mixer popovers (the Properties panel has the Control bar's Fill and Stroke chips, Stroke link and weight spinner, with nothing selected too), panels have Illustrator's Window menu keys (Align Shift+F7, Transform Shift+F8, Pathfinder Cmd+Shift+F9, Layers F7, Character Cmd+T…; every panel can be given one in Edit › Keyboard Shortcuts), and Eyedropper Options pick up and apply chosen attributes (Alt and Shift+Alt, image pixels). An ICC CMYK profile converts straight into the RGB working space (not through sRGB, so a wider space such as Wide Gamut RGB keeps colours sRGB can't hold) with the colour settings' black-point compensation, on the canvas and in RGB exports alike. Fills and strokes can overprint (Attributes panel, Overprint Black options), and CMYK documents blend in inks on screen, in PDF and when flattening. Document Color Mode converts the art, symbols, pattern tiles and swatches through the colour settings: Gray stays Gray, RGB greys separate into four-colour greys and a rich black as Illustrator does, or go on the black plate only with `grays: "black"` (also for `document.open {colorMode}`).
   - **Gradients:** lossless, validated gradient params; gradients follow rotate, reflect, shear, non-uniform scale and distortions; the Gradient tool edits the fill or stroke of the active proxy, type included; an interactive on-canvas annotator (move, length/angle, rotate, add/move/delete/duplicate stops, midpoints, a stop popover, Delete and arrow keys). The Gradient panel has the Fill/Stroke proxy, a gradient-swatch dropdown with Save to Swatches, midpoint locations, Alt-drag to copy or swap stops, swatch drops on the ramp and a stop eyedropper; copied appearances and graphic styles place gradients on each target's own bounds; gradient handles snap and honour Constrain Angle. Gradient stops stay linked to global and spot swatches. Freeform gradients (points and lines) are edited on the canvas; radial gradients have an extent ellipse, an aspect handle and an off-centre focal point (SVG `fx`/`fy`, PDF two-point radials). A stroke's gradient runs within, along or across it. Object ▸ Expand turns gradients into N objects or a gradient mesh.
   - **Strokes:** one stroke-geometry module shared by the canvas, SVG, PDF and Outline Stroke; dotted lines (zero-length dashes draw dots or squares); arrowheads with hollow outlines, tip-on-end or extend-past-end alignment and one opacity for line and head. SVG and PDF export arrowheads, width profiles, brushes and aligned strokes exactly as the canvas draws them; Outline Stroke and the live Outline Stroke effect outline every stroke item as drawn (dashes, heads, profiles, alignment); dashes can be fitted to corners and path ends; width profiles carry through dashes, and their corners take the join. The Stroke panel edits type's character strokes, follows the stroke units (its weight presets are round values in that unit: `0.25 mm`, `0.0625 in`, `1 px`, #426; fields show four decimals in mm, cm and inches, three in points), shows mixed values blank and opens from the Control bar. A width profile library, thirty more arrowheads, and Width Point Edit with multi-select and discontinuous points. Visual bounds and clicks cover the whole painted stroke. Scale Strokes & Effects, Scale Corners and Use Preview Bounds work everywhere, and new art inherits stroke options, a graphic style or the whole last appearance.
   - **Appearance:** the Appearance panel's selected row drives every paint, stroke, gradient and transparency edit (`item` on the commands); effects apply to one fill or stroke; per-item Opacity popups, whose blend-mode list and opacity slider stay open inside them (#430; the Control bar's Stroke popover too); Mixed Appearances, Layers target dots and basic-appearance rules. Effects can be reordered, moved between items and copied by dragging; Show All Hidden Attributes; clicking an effect edits it in place; the object thumbnail drags onto art; effects render on type, images, symbols, blends, envelopes, meshes and repeats, and per-item raster effects export. Groups, layers and type have their own fills, strokes and effects (Contents and Characters rows); the Layers panel's target circles target layers, groups and objects; Expand Appearance turns fills, strokes, effects and brushes into objects.

crates/color/src/cms/icc.rs

@@ -1,7 +1,7 @@
 //! ICC profiles through `moxcms` (pure Rust): built-in RGB spaces and user-supplied `.icc` files,
 //! and the profiles exports embed ([`encode_builtin`]), written in code from the CMS.
 
-use std::sync::{Arc, OnceLock};
+use std::sync::{Arc, Mutex, OnceLock};
 
 use moxcms::{
     ColorProfile, DataColorSpace, Layout, LocalizableString, LutMultidimensionalType, LutStore, LutWarehouse, Matrix3d, ProfileClass, ProfileText,
@@ -27,6 +27,9 @@ fn intent_index(i: Intent) -> usize {
 
 type Xf = Option<Arc<TransformF32Executor>>;
 
+/// A direct transform's cache key: destination name, intent index, black-point compensation.
+type DirectKey = (String, usize, bool);
+
 /// A parsed ICC profile plus lazily-built transforms to/from sRGB.
 pub struct IccProfile {
     pub name: String,
@@ -37,6 +40,21 @@ pub struct IccProfile {
     srgb: ColorProfile,
     to_srgb: [OnceLock<Xf>; 4],
     from_srgb: [OnceLock<Xf>; 4],
+    /// Direct transforms into other RGB profiles ([`Self::to_rgb_of`]), by destination, intent
+    /// and black-point compensation.
+    direct: Mutex<Vec<(DirectKey, Option<Arc<Direct>>)>>,
+}
+
+/// A transform from one profile into an RGB profile without passing through sRGB: into the
+/// destination's primaries with linear tone curves, where black-point compensation is a linear
+/// remap, then onto its own curves.
+struct Direct {
+    to_linear: Arc<TransformF32Executor>,
+    /// Linear → the destination's curves; `None` when the destination isn't a matrix profile
+    /// (the first transform goes straight into it, without compensation).
+    to_dest: Option<Arc<TransformF32Executor>>,
+    /// The source black's luminance in the linear destination (0: no compensation).
+    black: f32,
 }
 
 impl std::fmt::Debug for IccProfile {
@@ -72,6 +90,7 @@ impl IccProfile {
             srgb: ColorProfile::new_srgb(),
             to_srgb: Default::default(),
             from_srgb: Default::default(),
+            direct: Mutex::new(Vec::new()),
         })
     }
 
@@ -135,6 +154,72 @@ impl IccProfile {
         Some(dst.into_iter().map(|x| x.clamp(0.0, 1.0)).collect())
     }
 
+    /// Device values (RGB / CMYK / Gray, 0..1) → `dest`'s RGB, converted directly with `intent`:
+    /// not through sRGB, so colours outside sRGB keep their place in a wider space. With `bpc`
+    /// (and an intent other than absolute), this profile's black maps onto the destination's
+    /// black (black-point compensation, the darkest ink the profile prints becoming RGB 0 rather
+    /// than a dark grey). `None` when `dest` isn't RGB or no transform can be built.
+    pub fn to_rgb_of(&self, dest: &IccProfile, v: &[f32], intent: Intent, bpc: bool) -> Option<[f32; 3]> {
+        let t = self.direct_xf(dest, intent, bpc && intent != Intent::AbsoluteColorimetric)?;
+        let mut src = v.to_vec();
+        src.resize(self.channels(), 0.0);
+        let mut lin = [0.0f32; 3];
+        t.to_linear.transform(&src, &mut lin).ok()?;
+        let Some(to_dest) = &t.to_dest else { return Some(lin.map(|x| x.clamp(0.0, 1.0))) };
+        if t.black > 0.0 {
+            lin = lin.map(|x| (x - t.black) / (1.0 - t.black));
+        }
+        let lin = lin.map(|x| x.clamp(0.0, 1.0));
+        let mut out = [0.0f32; 3];
+        to_dest.transform(&lin, &mut out).ok()?;
+        Some(out.map(|x| x.clamp(0.0, 1.0)))
+    }
+
+    fn direct_xf(&self, dest: &IccProfile, intent: Intent, bpc: bool) -> Option<Arc<Direct>> {
+        if dest.kind != ProfileKind::Rgb {
+            return None;
+        }
+        let key = (dest.name.clone(), intent_index(intent), bpc);
+        let mut cache = self.direct.lock().unwrap_or_else(|e| e.into_inner());
+        if let Some((_, t)) = cache.iter().find(|(k, _)| *k == key) {
+            return t.clone();
+        }
+        let t = self.build_direct(dest, intent, bpc).map(Arc::new);
+        cache.push((key, t.clone()));
+        t
+    }
+
+    fn build_direct(&self, dest: &IccProfile, intent: Intent, bpc: bool) -> Option<Direct> {
+        let d = &dest.profile;
+        let matrix = d.red_trc.is_some() && d.green_trc.is_some() && d.blue_trc.is_some();
+        if !matrix {
+            let xf = self.profile.create_transform_f32(self.layout(), d, Layout::Rgb, Self::opts(intent)).ok()?;
+            return Some(Direct { to_linear: xf, to_dest: None, black: 0.0 });
+        }
+        let mut linear = d.clone();
+        for trc in [&mut linear.red_trc, &mut linear.green_trc, &mut linear.blue_trc] {
+            *trc = Some(ToneReprCurve::Parametric(vec![1.0]));
+        }
+        // A coding-independent code point names the transfer curve outright (moxcms's sRGB has
+        // one) and would override the linear curves.
+        linear.cicp = None;
+        let to_linear = self.profile.create_transform_f32(self.layout(), &linear, Layout::Rgb, Self::opts(intent)).ok()?;
+        let to_dest = linear.create_transform_f32(Layout::Rgb, d, Layout::Rgb, Self::opts(Intent::RelativeColorimetric)).ok()?;
+        // The source black: the darkest colour the profile reproduces, found as lcms does for an
+        // output profile (black sent into the profile and read back), made neutral.
+        let black = if bpc && self.kind == ProfileKind::Cmyk {
+            let inks = self.from_srgb([0.0; 3], Intent::RelativeColorimetric)?;
+            let mut lin = [0.0f32; 3];
+            to_linear.transform(&inks, &mut lin).ok()?;
+            let y = |c: &moxcms::Xyzd| c.y as f32;
+            let lum = lin[0] * y(&d.red_colorant) + lin[1] * y(&d.green_colorant) + lin[2] * y(&d.blue_colorant);
+            lum.clamp(0.0, 0.5)
+        } else {
+            0.0
+        };
+        Some(Direct { to_linear, to_dest: Some(to_dest), black })
+    }
+
     /// Whether transforms can be built for this profile (checked at registration).
     pub fn usable(&self) -> bool {
         self.to_xf(Intent::RelativeColorimetric).is_some() && self.inverse_xf(Intent::RelativeColorimetric).is_some()

crates/color/src/cms/mod.rs

@@ -356,10 +356,37 @@ impl Cms {
         }
     }
 
-    /// CMYK in the working space → display sRGB (`absolute` simulates the paper colour).
+    /// CMYK in the working space → display sRGB (`absolute` simulates the paper colour). An ICC
+    /// CMYK profile converts as [`Self::cmyk_to_rgb`] does into sRGB (with the settings'
+    /// black-point compensation), so what shows is what an RGB export writes.
     pub fn cmyk_to_srgb(&self, cmyk: [f32; 4], absolute: bool) -> [f32; 3] {
+        if let (false, CmykSpace::Icc(p)) = (absolute, &self.cmyk)
+            && let Some(srgb) = builtin_rgb_cache(SRGB)
+            && let Some(v) = p.to_rgb_of(&srgb, &cmyk.map(|v| v.clamp(0.0, 1.0)), Intent::RelativeColorimetric, self.settings.bpc)
+        {
+            return v;
+        }
         Self::cmyk_to_srgb_in(&self.cmyk, cmyk, absolute)
     }
+    /// CMYK in the working space → working RGB with `intent`. An ICC CMYK profile converts
+    /// directly into the RGB profile: not through display sRGB, which would clip colours a wider
+    /// RGB space holds (Wide Gamut RGB keeps CMYK cyan that sRGB can't show), and with the
+    /// settings' black-point compensation. The built-in CMYK spaces go through sRGB as before
+    /// (Generic CMYK compensates in its own model).
+    pub fn cmyk_to_rgb(&self, cmyk: [f32; 4], intent: Intent) -> [f32; 3] {
+        let cmyk = cmyk.map(|v| v.clamp(0.0, 1.0));
+        let src = match &self.cmyk {
+            CmykSpace::Icc(p) => Some(p.clone()),
+            CmykSpace::Generic(_) | CmykSpace::Device => None,
+        };
+        let dest = match &self.rgb {
+            RgbSpace::Icc(p) => Some(p.clone()),
+            RgbSpace::Srgb => builtin_rgb_cache(SRGB),
+        };
+        src.zip(dest)
+            .and_then(|(s, d)| s.to_rgb_of(&d, &cmyk, intent, self.settings.bpc))
+            .unwrap_or_else(|| self.srgb_to_rgb(self.cmyk_to_srgb(cmyk, false)))
+    }
     /// Display sRGB → working CMYK with `intent`.
     pub fn srgb_to_cmyk(&self, srgb: [f32; 3], intent: Intent) -> [f32; 4] {
         Self::srgb_to_cmyk_in(&self.cmyk, srgb, intent, self.settings.bpc)
@@ -424,6 +451,10 @@ impl Cms {
                 let [c, m, y, k] = self.to_cmyk(c, intent);
                 Color::Cmyk { c, m, y, k }
             }
+            (Color::Cmyk { c, m, y, k }, Model::Rgb) => {
+                let [r, g, b] = self.cmyk_to_rgb([*c, *m, *y, *k], intent);
+                Color::Rgb { r, g, b }
+            }
             (_, Model::Rgb) => {
                 let [r, g, b] = self.srgb_to_rgb(self.display_rgb(c));
                 Color::Rgb { r, g, b }

crates/color/src/cms/tests_icc.rs

@@ -60,3 +60,54 @@ fn a_loaded_profile_is_embedded_as_loaded() {
     register_icc(&bytes, Some("Embedded As Loaded RGB".into())).unwrap();
     assert_eq!(&*icc_bytes("Embedded As Loaded RGB").unwrap(), &bytes[..]);
 }
+
+/// Settings with an ICC CMYK profile (Generic CMYK's, loaded as a file is) and Wide Gamut RGB.
+fn icc_cmyk(bpc: bool) -> Cms {
+    let name = register_icc(&icc_bytes(GENERIC_CMYK).unwrap(), Some("Test ICC CMYK".into())).unwrap().name;
+    Cms::new(&ColorSettings { rgb: WIDE_GAMUT_RGB.into(), cmyk: name, bpc, ..ColorSettings::default() }).unwrap()
+}
+
+#[test]
+fn icc_cmyk_converts_into_a_wide_rgb_space_directly_without_clipping_to_srgb() {
+    let wide = icc_cmyk(true);
+    let cyan = [1.0, 0.0, 0.0, 0.0];
+    let direct = wide.cmyk_to_rgb(cyan, Intent::RelativeColorimetric);
+    // Through sRGB, cyan clips to sRGB's gamut first: in the wider space that reads as a red
+    // channel well above zero.
+    let hub = wide.srgb_to_rgb(wide.cmyk_to_srgb(cyan, false));
+    assert!(direct[0] + 0.15 < hub[0], "direct {direct:?}, through sRGB {hub:?}");
+    // Same colour either way where sRGB holds it: a mid grey and paper white.
+    for inks in [[0.0, 0.0, 0.0, 0.5], [0.0; 4]] {
+        let (d, h) = (wide.cmyk_to_rgb(inks, Intent::RelativeColorimetric), wide.srgb_to_rgb(wide.cmyk_to_srgb(inks, false)));
+        assert!(d.iter().zip(h).all(|(a, b)| (a - b).abs() < 0.02), "{inks:?}: direct {d:?}, through sRGB {h:?}");
+    }
+    // Cms::convert takes the direct route for CMYK.
+    let Color::Rgb { r, .. } = wide.convert(&Color::Cmyk { c: 1.0, m: 0.0, y: 0.0, k: 0.0 }, Model::Rgb, Intent::RelativeColorimetric) else {
+        panic!("RGB")
+    };
+    assert!((r - direct[0]).abs() < 1e-6);
+}
+
+#[test]
+fn black_point_compensation_maps_the_darkest_ink_to_rgb_black() {
+    let rich = [0.75, 0.68, 0.67, 0.9];
+    let (on, off) = (icc_cmyk(true).cmyk_to_rgb(rich, Intent::RelativeColorimetric), icc_cmyk(false).cmyk_to_rgb(rich, Intent::RelativeColorimetric));
+    // Without compensation the profile's black is a dark grey; with it, rich black goes most of
+    // the way to RGB black (not all: it isn't quite the darkest ink the profile prints).
+    assert!(off.iter().all(|v| *v > 0.1), "without: {off:?}");
+    assert!(on.iter().zip(off).all(|(a, b)| *a < 0.08 && *a < b * 0.5), "with: {on:?}, without: {off:?}");
+    // The screen shows what an sRGB conversion writes, compensated alike.
+    let srgb = |bpc| {
+        let c = icc_cmyk(bpc);
+        Cms::new(&ColorSettings { rgb: SRGB.into(), ..c.settings().clone() }).unwrap()
+    };
+    for bpc in [true, false] {
+        let c = srgb(bpc);
+        assert_eq!(c.cmyk_to_srgb(rich, false), c.cmyk_to_rgb(rich, Intent::RelativeColorimetric), "bpc {bpc}");
+    }
+    // White is untouched, and absolute colorimetric never compensates.
+    let white = icc_cmyk(true).cmyk_to_rgb([0.0; 4], Intent::RelativeColorimetric);
+    assert!(white.iter().all(|v| *v > 0.99), "{white:?}");
+    let abs = |bpc| icc_cmyk(bpc).cmyk_to_rgb(rich, Intent::AbsoluteColorimetric);
+    assert_eq!(abs(true), abs(false));
+}

crates/pdf/src/output.rs

@@ -375,6 +375,11 @@ impl Dest {
                 };
                 Color::Cmyk { c, m, y, k }
             }
+            // CMYK straight into the destination RGB (the destination shares the source's CMYK).
+            (_, Color::Cmyk { c, m, y, k }) => {
+                let [r, g, b] = self.cms.cmyk_to_rgb([*c, *m, *y, *k], intent);
+                Color::Rgb { r, g, b }
+            }
             _ => {
                 let [r, g, b] = self.cms.srgb_to_rgb(source.display_rgb(c));
                 Color::Rgb { r, g, b }