aleleba/vectorcraft
1
0
Fork 0
mirror of https://github.com/storytold/vectorcraft.git synced 2026-11-11 16:33:22 -06:00
Code Issues Packages Projects Releases Wiki Activity

Image Trace: Document Library keeps neutral tones off saturated library colors

Browse Source 
With the Document Library palette, each pixel took the library color
nearest in plain Oklab distance. A 50% gray lies nearer in that distance
to a saturated blue of the same lightness than to black or a light
cream, and a muted brown is also nearer to the blue than to either. With
a black, cream and blue library, both traced as the blue.

This changes how Document Library matches pixels: each pixel now takes
the library color nearest with differences in hue and chroma (Oklab a
and b) counted three times as much as lightness. The same measure picks
which library colors are used. Neutral and muted tones take a neutral
library color, and the other palettes are unchanged.
This commit is contained in:
dotCooCoo
2026-10-26 09:09:45 +07:00
committed by bflatastic
parent 0629d4e9a5
commit c9cc2ef076
5 changed files with 68 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files
crates/trace/src/quantize.rs
+25 -8
View File
@@ -110,19 +110,17 @@ pub(crate) fn quantize_keeping(img: &Raster, params: &TraceParams) -> (Quantized
}
let mut lut = vec![0u16; 1 << 15];
let center_labs = labs(&centers);
let library = params.palette == Palette::DocumentLibrary && !params.swatches.is_empty();
let nearest = if library { nearest_library } else { nearest_lab };
for (i, c, _) in &every {
lut[*i] = nearest_lab(&center_labs, oklab(*c)) as u16;
lut[*i] = nearest(&center_labs, oklab(*c)) as u16;
}
let labels =
img.rgba.as_chunks::<4>().0.iter().map(|p| if p[3] < 128 { TRANSPARENT } else { lut[hk.key(p[0], p[1], p[2])] }).collect();
let palette = centers.iter().map(|c| [c[0].round() as u8, c[1].round() as u8, c[2].round() as u8]).collect();
let q = compact(labels, palette);
// A swatch library's colours are used as they are.
if params.palette == Palette::DocumentLibrary && !params.swatches.is_empty() {
q
} else {
merge_mixed(q, img.width as usize, img.height as usize, &rare)
}
if library { q } else { merge_mixed(q, img.width as usize, img.height as usize, &rare) }
};
let q = reduce(params.colors);
let q = settled(q, img, &own);
@@ -614,6 +612,24 @@ fn nearest_lab(labs: &[[f64; 3]], c: [f64; 3]) -> usize {
best.1
}
/// How much more a difference in hue and chroma (Oklab a and b) counts than one in lightness when
/// a pixel takes a library color.
const LIBRARY_CHROMA_WEIGHT: f64 = 3.0;
/// The index of the library color of `labs` (Oklab) nearest to `c` (Oklab), with differences in
/// hue and chroma counted [`LIBRARY_CHROMA_WEIGHT`] times: a neutral or muted tone takes a neutral
/// library color of another lightness rather than a saturated one of its own lightness.
fn nearest_library(labs: &[[f64; 3]], c: [f64; 3]) -> usize {
let mut best = (f64::INFINITY, 0);
for (i, m) in labs.iter().enumerate() {
let d = (m[0] - c[0]).powi(2) + (LIBRARY_CHROMA_WEIGHT * (m[1] - c[1])).powi(2) + (LIBRARY_CHROMA_WEIGHT * (m[2] - c[2])).powi(2);
if d < best.0 {
best = (d, i);
}
}
best.1
}
fn labs(colors: &[[f64; 3]]) -> Vec<[f64; 3]> {
colors.iter().map(|c| oklab(*c)).collect()
}
@@ -678,7 +694,8 @@ fn flat_colors(used: &[Used], detail: f64) -> Option<usize> {
/// The most histogram bins flat art's main colours spread over (a few bins per colour).
const FLAT_BINS: usize = 96;
/// Document Library: the `k` swatches (at most) that the most pixels are nearest to.
/// Document Library: the `k` swatches (at most) that the most pixels are nearest to (see
/// [`nearest_library`]).
fn library_colors(used: &[Used], swatches: &[[u8; 3]], k: usize) -> Vec<[f64; 3]> {
let mut all: Vec<[f64; 3]> = vec![];
for s in swatches {
@@ -690,7 +707,7 @@ fn library_colors(used: &[Used], swatches: &[[u8; 3]], k: usize) -> Vec<[f64; 3]
let mut weight = vec![0.0; all.len()];
let all_labs = labs(&all);
for (_, c, n) in used {
if let Some(w) = weight.get_mut(nearest_lab(&all_labs, oklab(*c))) {
if let Some(w) = weight.get_mut(nearest_library(&all_labs, oklab(*c))) {
*w += n;
}
}