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591 lines
23 KiB
Rust
591 lines
23 KiB
Rust
//! Synthetic CMYK output profiles.
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//!
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//! Adobe's CMYK profiles (U.S. Web Coated SWOP, Coated FOGRA39 …) are proprietary, and the
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//! freely downloadable characterisation-based profiles come with redistribution conditions, so
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//! this crate ships a CMYK profile it generates itself from a documented printer model:
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//!
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//! * **Forward model** (CMYK → XYZ): Yule–Nielsen modified Neugebauer (n = 2) over the 16
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//! ink overprints, with Demichel coverage weights and a parabolic tone value increase (dot
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//! gain) per ink. The eight K-free primaries use the published ISO 12647-2 coated-paper Lab
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//! aim values (paper, C, M, Y, the three two-colour overprints) and an estimated three-colour
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//! black; overprints with black are derived multiplicatively with a first-surface reflection
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//! floor.
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//! * **AToB** (all intents): 11⁴ `lut16` table of the forward model, relative colorimetric
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//! (paper → L* 100).
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//! * **BToA1** (colorimetric): for every Lab node, black generation (GCR) from the gray
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//! component of the K-free solution, then a bounded least-squares solve for C, M, Y with the
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//! total ink limit; out-of-gamut colours land on the closest reachable colour (clipping).
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//! * **BToA0/BToA2** (perceptual/saturation): the target is first compressed into the gamut —
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//! L* is scaled onto the device black, chroma is softly compressed against a gamut boundary
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//! descriptor sampled from the forward model — then solved as above.
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//!
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//! The model is plausible for coated offset, not a measured characterisation: use a real
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//! profile from your print provider for production print.
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//!
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//! [`cmyk_profile_from_model`] builds the same tables from any [`Forward`] model, inverting its
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//! sampled AToB table; the Coated FOGRA39 built-in is made that way from a model fitted to
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//! Fogra's measurements (`tests/fogra39.rs`).
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use crate::clut::Clut;
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use crate::curve::Curve;
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use crate::math;
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use crate::pipeline::Stage;
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use crate::profile::{ColorSpace, Lut, LutKind, Pcs, Profile, ProfileClass};
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use crate::{CmsError, Intent, invalid_arg};
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pub const DESCRIPTION: &str = "PhotoCraft Coated CMYK (synthetic, 300% TAC, medium GCR)";
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/// Parameters of the synthetic profile.
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#[derive(Clone, Debug)]
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pub struct CmykParams {
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pub description: String,
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/// Copyright tag text.
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pub copyright: String,
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/// Total area coverage limit (3.0 = 300 %).
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pub tac: f64,
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/// Gray component (min of C, M, Y of the K-free solution) where black generation starts.
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pub gcr_start: f64,
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/// Maximum black.
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pub k_max: f64,
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/// Exponent of the black generation curve above `gcr_start`.
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pub gcr_gamma: f64,
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/// Tone value increase at 50 % for C, M, Y, K.
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pub tvi: [f64; 4],
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/// Grid points of the AToB (4D) and BToA (3D) tables.
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pub grid_a2b: usize,
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pub grid_b2a: usize,
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/// Map paper and PCS white onto each other exactly: the AToB maps no ink to L* 100,
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/// a* = b* = 0, and the BToA input curves put that white on a grid node (`grid_b2a` must
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/// be odd), which holds no ink. Without them white falls between nodes of the legacy Lab
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/// encoding and separates to a trace of ink. Off by default, which keeps the bytes of the
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/// shipped Photocraft profile.
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pub white_on_node: bool,
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}
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impl Default for CmykParams {
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fn default() -> Self {
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CmykParams {
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description: DESCRIPTION.into(),
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copyright: crate::builtin::COPYRIGHT.into(),
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tac: 3.0,
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gcr_start: 0.2,
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k_max: 0.95,
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gcr_gamma: 1.1,
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tvi: [0.14, 0.14, 0.14, 0.17],
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grid_a2b: 11,
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grid_b2a: 21,
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white_on_node: false,
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}
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}
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}
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/// The printer model.
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#[derive(Clone, Debug)]
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pub struct CmykModel {
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/// Absolute XYZ (D50) of the 16 overprints, indexed by ink bit mask (C=1, M=2, Y=4, K=8),
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/// stored as `X^(1/n)` for the Yule–Nielsen sum.
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prim_n: [[f64; 3]; 16],
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/// Absolute XYZ of the paper.
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pub paper: [f64; 3],
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tvi: [f64; 4],
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}
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const YN: f64 = 2.0;
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impl CmykModel {
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pub fn coated(tvi: [f64; 4]) -> Self {
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let lab = |l: f64, a: f64, b: f64| math::lab_to_xyz([l, a, b], math::D50);
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// ISO 12647-2 (coated, paper type 1/2) Lab aims, D50/2°; CMY overprint estimated.
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let w = lab(95.0, 0.0, -2.0);
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let base: [[f64; 3]; 8] = [
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w, // paper
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lab(55.0, -37.0, -50.0), // C
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lab(48.0, 74.0, -3.0), // M
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lab(24.0, 22.0, -46.0), // C+M (blue)
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lab(89.0, -5.0, 93.0), // Y
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lab(50.0, -65.0, 27.0), // C+Y (green)
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lab(47.0, 68.0, 48.0), // M+Y (red)
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lab(23.0, 0.0, 0.0), // C+M+Y
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];
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let k = lab(16.0, 0.0, 0.0);
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// Overprints with black: multiplicative in reflectance above a first-surface floor.
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let floor = 0.006;
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let mut prim = [[0.0; 3]; 16];
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for (m, slot) in prim.iter_mut().enumerate() {
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let p = base[m & 7];
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*slot = if m & 8 == 0 {
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p
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} else {
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std::array::from_fn(|i| {
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let s = floor * w[i];
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s + (p[i] - s) * (k[i] - s) / (w[i] - s)
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})
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};
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}
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let prim_n = prim.map(|p| p.map(|v| v.max(0.0).powf(1.0 / YN)));
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CmykModel { prim_n, paper: w, tvi }
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}
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/// Absolute XYZ of an ink combination (each coverage in `[0, 1]`).
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pub fn xyz(&self, cmyk: [f64; 4]) -> [f64; 3] {
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let a: [f64; 4] = std::array::from_fn(|i| {
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let v = cmyk[i].clamp(0.0, 1.0);
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(v + 4.0 * self.tvi[i] * v * (1.0 - v)).clamp(0.0, 1.0)
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});
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let mut s = [0.0; 3];
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for (m, prim) in self.prim_n.iter().enumerate() {
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let mut w = 1.0;
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for (i, ai) in a.iter().enumerate() {
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w *= if m & (1 << i) != 0 { *ai } else { 1.0 - ai };
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}
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if w == 0.0 {
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continue;
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}
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for (acc, p) in s.iter_mut().zip(prim) {
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*acc += w * p;
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}
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}
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s.map(|v| v.powf(YN))
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}
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/// ICC-relative Lab (paper = L* 100).
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pub fn lab(&self, cmyk: [f64; 4]) -> [f64; 3] {
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let x = self.xyz(cmyk);
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let rel = [x[0] * math::D50[0] / self.paper[0], x[1] * math::D50[1] / self.paper[1], x[2] * math::D50[2] / self.paper[2]];
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math::xyz_to_lab(rel, math::D50)
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}
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}
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/// A printer model: CMYK coverages (each in `[0, 1]`) → ICC-relative Lab (paper = L* 100).
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/// The separation solves and the gamut boundary invert it.
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pub trait Forward: Sync {
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fn lab(&self, cmyk: [f64; 4]) -> [f64; 3];
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}
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impl Forward for CmykModel {
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fn lab(&self, cmyk: [f64; 4]) -> [f64; 3] {
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CmykModel::lab(self, cmyk)
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}
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}
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/// A forward model read from a sampled AToB table: 4 inputs, legacy (`lut16`) Lab outputs, as
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/// [`sample_a2b`] makes it.
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struct TableForward(Clut);
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impl Forward for TableForward {
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fn lab(&self, cmyk: [f64; 4]) -> [f64; 3] {
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let mut o = [0.0f32; 3];
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self.0.interp(&cmyk.map(|v| v.clamp(0.0, 1.0) as f32), &mut o);
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decode_v2(o.map(f64::from))
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}
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}
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/// Bounded least-squares solve for C, M, Y given K, minimising ΔE76 to `target`, subject to
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/// `C + M + Y ≤ limit` (projected Levenberg–Marquardt with a numerical Jacobian).
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fn solve_cmy<F: Forward + ?Sized>(model: &F, target: [f64; 3], k: f64, limit: f64, seeds: &[[f64; 3]]) -> ([f64; 3], f64) {
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let project = |mut x: [f64; 3]| {
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for _ in 0..4 {
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for v in &mut x {
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*v = v.clamp(0.0, 1.0);
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}
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let s: f64 = x.iter().sum();
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if s <= limit + 1e-12 {
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break;
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}
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let active = x.iter().filter(|v| **v > 0.0).count().max(1) as f64;
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let d = (s - limit) / active;
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for v in &mut x {
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if *v > 0.0 {
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*v -= d;
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}
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}
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}
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x
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};
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let err = |x: [f64; 3]| {
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let l = model.lab([x[0], x[1], x[2], k]);
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[l[0] - target[0], l[1] - target[1], l[2] - target[2]]
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};
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let norm2 = |e: [f64; 3]| e[0] * e[0] + e[1] * e[1] + e[2] * e[2];
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let mut best = ([0.0; 3], f64::INFINITY);
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for seed in seeds {
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let mut x = project(*seed);
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let mut e = err(x);
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let mut f = norm2(e);
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let mut lambda = 1e-3;
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for _ in 0..60 {
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// Jacobian (3×3) by forward differences.
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let h = 1e-5;
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let mut j = [[0.0; 3]; 3];
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for c in 0..3 {
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let mut xp = x;
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xp[c] += h;
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let ep = err(xp);
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for r in 0..3 {
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j[r][c] = (ep[r] - e[r]) / h;
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}
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}
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// (JᵀJ + λ diag) δ = −Jᵀe
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let mut a = [[0.0; 3]; 3];
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let mut g = [0.0; 3];
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for r in 0..3 {
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for c in 0..3 {
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a[r][c] = (0..3).map(|k| j[k][r] * j[k][c]).sum();
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}
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g[r] = -(0..3).map(|k| j[k][r] * e[k]).sum::<f64>();
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}
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let mut improved = false;
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for _ in 0..8 {
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let mut al = a;
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for (d, row) in al.iter_mut().enumerate() {
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row[d] += lambda * (1.0 + a[d][d]);
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}
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let Some(inv) = math::invert(&al) else {
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lambda *= 10.0;
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continue;
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};
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let step = math::apply(&inv, g);
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let xn = project([x[0] + step[0], x[1] + step[1], x[2] + step[2]]);
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let en = err(xn);
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let fnew = norm2(en);
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if fnew < f {
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let moved = (0..3).map(|i| (xn[i] - x[i]).abs()).fold(0.0, f64::max);
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x = xn;
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e = en;
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f = fnew;
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lambda = (lambda * 0.3).max(1e-9);
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improved = moved > 1e-9;
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break;
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}
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lambda *= 10.0;
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}
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if !improved || f < 1e-10 {
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break;
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}
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}
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if f < best.1 {
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best = (x, f);
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}
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if best.1 < 1e-6 {
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break;
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}
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}
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(best.0, best.1.sqrt())
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}
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const SEEDS: [[f64; 3]; 5] = [[0.3, 0.3, 0.3], [0.05, 0.05, 0.05], [0.8, 0.8, 0.8], [0.9, 0.2, 0.2], [0.2, 0.9, 0.9]];
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/// Colorimetric separation of a relative Lab target: GCR black generation then a CMY solve.
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pub fn separate<F: Forward + ?Sized>(model: &F, p: &CmykParams, target: [f64; 3], warm: Option<[f64; 4]>) -> ([f64; 4], f64) {
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let mut seeds: Vec<[f64; 3]> = warm.map(|w| vec![[w[0], w[1], w[2]]]).unwrap_or_default();
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seeds.extend_from_slice(&SEEDS);
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let (cmy0, _) = solve_cmy(model, target, 0.0, 3.0, &seeds);
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let g = cmy0[0].min(cmy0[1]).min(cmy0[2]);
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let k = if g <= p.gcr_start { 0.0 } else { p.k_max * ((g - p.gcr_start) / (1.0 - p.gcr_start)).powf(p.gcr_gamma) };
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let mut seeds2 = vec![[(cmy0[0] - k).max(0.0), (cmy0[1] - k).max(0.0), (cmy0[2] - k).max(0.0)], cmy0];
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seeds2.extend_from_slice(&seeds);
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let (cmy, de) = solve_cmy(model, target, k, (p.tac - k).max(0.0), &seeds2);
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([cmy[0], cmy[1], cmy[2], k], de)
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}
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/// Gamut boundary descriptor: maximum chroma per (L*, hue) bin, sampled from the model.
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struct Gbd {
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l_bins: usize,
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h_bins: usize,
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cmax: Vec<f64>,
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black_l: f64,
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}
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impl Gbd {
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fn new<F: Forward + ?Sized>(model: &F, p: &CmykParams) -> Self {
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let (l_bins, h_bins) = (41usize, 72usize);
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let mut cmax = vec![0.0f64; l_bins * h_bins];
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let n = 21;
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let mut black_l = 100.0f64;
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for ci in 0..n {
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for mi in 0..n {
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for yi in 0..n {
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for ki in 0..11 {
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let v = [ci as f64 / (n - 1) as f64, mi as f64 / (n - 1) as f64, yi as f64 / (n - 1) as f64, ki as f64 / 10.0];
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if v.iter().sum::<f64>() > p.tac + 1e-9 {
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continue;
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}
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let lab = model.lab(v);
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black_l = black_l.min(lab[0]);
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let c = lab[1].hypot(lab[2]);
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let h = lab[2].atan2(lab[1]).rem_euclid(std::f64::consts::TAU);
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let li = ((lab[0] / 100.0) * (l_bins - 1) as f64).round().clamp(0.0, (l_bins - 1) as f64) as usize;
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let hi = ((h / std::f64::consts::TAU) * h_bins as f64).round() as usize % h_bins;
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let e = &mut cmax[li * h_bins + hi];
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*e = e.max(c);
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}
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}
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}
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}
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// Fill holes and smooth: max over a 3×3 neighbourhood, then a box blur.
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let get = |v: &Vec<f64>, l: isize, h: isize| {
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let l = l.clamp(0, l_bins as isize - 1) as usize;
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let h = h.rem_euclid(h_bins as isize) as usize;
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v[l * h_bins + h]
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};
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let mut filled = cmax.clone();
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for l in 0..l_bins as isize {
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for h in 0..h_bins as isize {
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let mut m = 0.0f64;
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for dl in -1..=1 {
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for dh in -1..=1 {
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m = m.max(get(&cmax, l + dl, h + dh));
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}
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}
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filled[l as usize * h_bins + h as usize] = m;
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}
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}
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let mut smooth = filled.clone();
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for l in 0..l_bins as isize {
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for h in 0..h_bins as isize {
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let mut s = 0.0;
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for dl in -1..=1 {
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for dh in -1..=1 {
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s += get(&filled, l + dl, h + dh);
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}
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}
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smooth[l as usize * h_bins + h as usize] = s / 9.0;
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}
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}
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Gbd { l_bins, h_bins, cmax: smooth, black_l }
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}
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fn max_chroma(&self, l: f64, h: f64) -> f64 {
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let lp = (l / 100.0).clamp(0.0, 1.0) * (self.l_bins - 1) as f64;
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let hp = (h.rem_euclid(std::f64::consts::TAU) / std::f64::consts::TAU) * self.h_bins as f64;
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let (l0, h0) = (lp.floor() as usize, hp.floor() as usize);
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let (fl, fh) = (lp - l0 as f64, hp - h0 as f64);
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let l1 = (l0 + 1).min(self.l_bins - 1);
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let (h0m, h1m) = (h0 % self.h_bins, (h0 + 1) % self.h_bins);
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let v = |l: usize, h: usize| self.cmax[l * self.h_bins + h];
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let a = v(l0, h0m) + (v(l0, h1m) - v(l0, h0m)) * fh;
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let b = v(l1, h0m) + (v(l1, h1m) - v(l1, h0m)) * fh;
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a + (b - a) * fl
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}
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/// Perceptual gamut compression of a relative Lab colour.
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fn compress(&self, lab: [f64; 3]) -> [f64; 3] {
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let l = self.black_l + lab[0].clamp(0.0, 100.0) * (100.0 - self.black_l) / 100.0;
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let c = lab[1].hypot(lab[2]);
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if c < 1e-9 {
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return [l, 0.0, 0.0];
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}
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let h = lab[2].atan2(lab[1]);
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let cm = self.max_chroma(l, h).max(1e-3);
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let knee = 0.8 * cm;
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let c2 = if c <= knee { c } else { knee + (cm - knee) * ((c - knee) / (cm - knee)).tanh() };
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[l, c2 * h.cos(), c2 * h.sin()]
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}
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}
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fn lab_node_legacy(i: usize, n: usize) -> f64 {
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i as f64 / (n - 1) as f64
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}
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/// Decodes a legacy (lut16) Lab node coordinate triple.
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fn decode_v2(v: [f64; 3]) -> [f64; 3] {
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[v[0] * 100.0 * 65535.0 / 65280.0, v[1] * 65535.0 / 256.0 - 128.0, v[2] * 65535.0 / 256.0 - 128.0]
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}
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fn encode_v2(lab: [f64; 3]) -> [f32; 3] {
|
||
[
|
||
(lab[0] / (100.0 * 65535.0 / 65280.0)).clamp(0.0, 1.0) as f32,
|
||
((lab[1] + 128.0) * 256.0 / 65535.0).clamp(0.0, 1.0) as f32,
|
||
((lab[2] + 128.0) * 256.0 / 65535.0).clamp(0.0, 1.0) as f32,
|
||
]
|
||
}
|
||
|
||
#[cfg(not(target_arch = "wasm32"))]
|
||
fn par_map<T: Send>(n: usize, f: impl Fn(usize) -> T + Sync + Send) -> Vec<T> {
|
||
use rayon::prelude::*;
|
||
(0..n).into_par_iter().map(f).collect()
|
||
}
|
||
|
||
#[cfg(target_arch = "wasm32")]
|
||
fn par_map<T: Send>(n: usize, f: impl Fn(usize) -> T + Sync + Send) -> Vec<T> {
|
||
(0..n).map(f).collect()
|
||
}
|
||
|
||
/// Grid coordinate of a legacy-encoded PCS value through the [`CmykParams::white_on_node`]
|
||
/// input curves: L* 0–100 spans the L axis (higher L* clips to the top node) and a*/b* −128 to
|
||
/// +128 span theirs, so L* 100, a* = b* = 0 is the top centre node of an odd grid.
|
||
fn white_node_curve(l_axis: bool, x: f64) -> f64 {
|
||
if l_axis { (x * 65535.0 / 65280.0).min(1.0) } else { x * 65535.0 / 65536.0 }
|
||
}
|
||
|
||
fn b2a_table<F: Forward + ?Sized>(model: &F, p: &CmykParams, gbd: Option<&Gbd>) -> Result<Clut, CmsError> {
|
||
let n = p.grid_b2a.max(2);
|
||
let nodes = n * n * n;
|
||
let step = (n - 1) as f64;
|
||
let vals = par_map(n * n, |row| {
|
||
// One (L, a) row along b, warm-starting each solve from its neighbour.
|
||
let (li, ai) = (row / n, row % n);
|
||
let mut warm = None;
|
||
let mut out = Vec::with_capacity(n * 4);
|
||
for bi in 0..n {
|
||
let lab = if p.white_on_node {
|
||
// The inverse of `white_node_curve` at the node.
|
||
[100.0 * li as f64 / step, 256.0 * ai as f64 / step - 128.0, 256.0 * bi as f64 / step - 128.0]
|
||
} else {
|
||
decode_v2([lab_node_legacy(li, n), lab_node_legacy(ai, n), lab_node_legacy(bi, n)])
|
||
};
|
||
let target = match gbd {
|
||
Some(g) => g.compress(lab),
|
||
None => lab,
|
||
};
|
||
let (cmyk, _) = if p.white_on_node && lab == [100.0, 0.0, 0.0] { ([0.0; 4], 0.0) } else { separate(model, p, target, warm) };
|
||
warm = Some(cmyk);
|
||
out.extend(cmyk.map(|v| v as f32));
|
||
}
|
||
out
|
||
});
|
||
let data: Vec<f32> = vals.into_iter().flatten().collect();
|
||
debug_assert_eq!(data.len(), nodes * 4);
|
||
Clut::new(vec![n; 3], 4, data)
|
||
}
|
||
|
||
/// Refuses grids below 2 nodes or above what a [`Clut`] holds, before anything is sampled.
|
||
fn check_grids(p: &CmykParams) -> Result<(), CmsError> {
|
||
let fits = |grid: usize, dims: u32, outputs: usize| {
|
||
grid >= 2 && grid.checked_pow(dims).and_then(|n| n.checked_mul(outputs)).is_some_and(|n| n <= crate::clut::MAX_VALUES)
|
||
};
|
||
if !fits(p.grid_a2b, 4, 3) || !fits(p.grid_b2a, 3, 4) {
|
||
return Err(invalid_arg(format!("CMYK profile grids {}⁴/{}³ need at least 2 nodes and must fit a CLUT", p.grid_a2b, p.grid_b2a)));
|
||
}
|
||
if p.white_on_node && p.grid_b2a.is_multiple_of(2) {
|
||
return Err(invalid_arg(format!("white on a node needs an odd BToA grid, not {}", p.grid_b2a)));
|
||
}
|
||
Ok(())
|
||
}
|
||
|
||
/// Input curves of a `lut16` table: identity, or the [`white_node_curve`]s for a BToA table.
|
||
fn lut16(clut: Clut, white_on_node: bool) -> Lut {
|
||
let (i, o) = (clut.inputs, clut.outputs);
|
||
let input = if white_on_node {
|
||
// mft2's longest input tables; white lies between samples, within a u16 step of its node.
|
||
let table = |l_axis: bool| Curve::Table((0..4096).map(|j| white_node_curve(l_axis, j as f64 / 4095.0) as f32).collect());
|
||
vec![table(true), table(false), table(false)]
|
||
} else {
|
||
vec![Curve::Table(vec![0.0, 1.0]); i]
|
||
};
|
||
Lut {
|
||
kind: LutKind::Lut16,
|
||
inputs: i,
|
||
outputs: o,
|
||
stages: vec![Stage::Curves(input), Stage::Clut(clut), Stage::Curves(vec![Curve::Table(vec![0.0, 1.0]); o])],
|
||
}
|
||
}
|
||
|
||
/// Generates a synthetic CMYK profile. Grids are refused as in [`cmyk_profile_from_model`].
|
||
pub fn cmyk_profile(p: &CmykParams) -> Result<Profile, CmsError> {
|
||
check_grids(p)?;
|
||
let model = CmykModel::coated(p.tvi);
|
||
let a2b = sample_a2b(&model, p)?;
|
||
lut_profile(&model, a2b, model.paper, p)
|
||
}
|
||
|
||
/// Samples a forward model into an AToB table with `p.grid_a2b`⁴ nodes and legacy Lab
|
||
/// encoding.
|
||
fn sample_a2b<F: Forward + ?Sized>(model: &F, p: &CmykParams) -> Result<Clut, CmsError> {
|
||
Clut::sample(vec![p.grid_a2b.max(2); 4], 3, |inp, out| {
|
||
let lab = if p.white_on_node && inp.iter().all(|v| *v == 0.0) {
|
||
[100.0, 0.0, 0.0]
|
||
} else {
|
||
model.lab([inp[0] as f64, inp[1] as f64, inp[2] as f64, inp[3] as f64])
|
||
};
|
||
out.copy_from_slice(&encode_v2(lab));
|
||
})
|
||
}
|
||
|
||
/// A CMYK profile of any forward model on paper with absolute XYZ `paper`: the AToB table
|
||
/// samples `model` on `p.grid_a2b`⁴ nodes, and the BToA tables invert that table rather than the
|
||
/// model, so Lab → CMYK → Lab round trips through the profile are as close as the separation
|
||
/// allows. Grids below 2 nodes or too large for a [`Clut`], and a zero, negative or
|
||
/// non-finite `paper`, are refused with [`CmsError::InvalidArgument`].
|
||
pub fn cmyk_profile_from_model<F: Forward + ?Sized>(model: &F, paper: [f64; 3], p: &CmykParams) -> Result<Profile, CmsError> {
|
||
check_grids(p)?;
|
||
if !paper.iter().all(|v| v.is_finite() && *v > 0.0) {
|
||
return Err(invalid_arg(format!("paper XYZ {paper:?}")));
|
||
}
|
||
let a2b = sample_a2b(model, p)?;
|
||
let forward = TableForward(a2b.clone());
|
||
lut_profile(&forward, a2b, paper, p)
|
||
}
|
||
|
||
fn lut_profile<F: Forward + ?Sized>(model: &F, a2b: Clut, paper: [f64; 3], p: &CmykParams) -> Result<Profile, CmsError> {
|
||
let gbd = Gbd::new(model, p);
|
||
let colorimetric = b2a_table(model, p, None)?;
|
||
let perceptual = b2a_table(model, p, Some(&gbd))?;
|
||
let a2b = lut16(a2b, false);
|
||
let (b0, b1) = (lut16(perceptual, p.white_on_node), lut16(colorimetric, p.white_on_node));
|
||
Ok(Profile {
|
||
version: (4, 0x30),
|
||
class: ProfileClass::Output,
|
||
color_space: ColorSpace::Cmyk,
|
||
pcs: Pcs::Lab,
|
||
rendering_intent: Intent::Perceptual,
|
||
description: p.description.clone(),
|
||
copyright: p.copyright.clone(),
|
||
white_point: paper.map(math::s15f16_round),
|
||
black_point: None,
|
||
chad: None,
|
||
matrix: None,
|
||
trc: None,
|
||
gray_trc: None,
|
||
a2b: [Some(a2b.clone()), Some(a2b.clone()), Some(a2b)],
|
||
b2a: [Some(b0.clone()), Some(b1), Some(b0)],
|
||
bytes: None,
|
||
hash: Default::default(),
|
||
}
|
||
.with_encoded_bytes())
|
||
}
|
||
|
||
/// The default coated profile (what `profiles/photocraft-coated-cmyk.icc` contains).
|
||
pub fn coated_cmyk() -> Result<Profile, CmsError> {
|
||
cmyk_profile(&CmykParams::default())
|
||
}
|
||
|
||
#[cfg(test)]
|
||
mod tests {
|
||
use super::*;
|
||
|
||
#[test]
|
||
fn model_anchors() {
|
||
let m = CmykModel::coated(CmykParams::default().tvi);
|
||
let w = m.lab([0.0; 4]);
|
||
assert!((w[0] - 100.0).abs() < 1e-9 && w[1].abs() < 1e-9 && w[2].abs() < 1e-9, "{w:?}");
|
||
let k = m.lab([0.0, 0.0, 0.0, 1.0]);
|
||
assert!(k[0] > 12.0 && k[0] < 22.0, "{k:?}");
|
||
let rich = m.lab([0.75, 0.65, 0.6, 0.9]);
|
||
assert!(rich[0] < k[0], "{rich:?}");
|
||
// Monotonic in each ink.
|
||
for ink in 0..4 {
|
||
let mut prev = 101.0;
|
||
for i in 0..=20 {
|
||
let mut v = [0.2, 0.2, 0.2, 0.2];
|
||
v[ink] = i as f64 / 20.0;
|
||
let l = m.lab(v)[0];
|
||
assert!(l < prev + 1e-9, "ink {ink} step {i}: {l} >= {prev}");
|
||
prev = l;
|
||
}
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn separation_hits_in_gamut_targets() {
|
||
let m = CmykModel::coated(CmykParams::default().tvi);
|
||
let p = CmykParams::default();
|
||
let reachable = [[0.3, 0.4, 0.1, 0.1], [0.6, 0.1, 0.5, 0.0], [0.05, 0.1, 0.7, 0.0], [0.5, 0.45, 0.45, 0.4]].map(|v| m.lab(v));
|
||
for target in [[50.0, 0.0, 0.0]].into_iter().chain(reachable) {
|
||
let (cmyk, de) = separate(&m, &p, target, None);
|
||
assert!(de < 1.5, "{target:?} -> {cmyk:?} ΔE {de}");
|
||
assert!(cmyk.iter().sum::<f64>() <= p.tac + 1e-6);
|
||
}
|
||
}
|
||
}
|