Use svd for dimensional reduction

Cargo.lock

@@ -373,6 +373,20 @@ name = "bytemuck"
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 checksum = "94bbb0ad554ad961ddc5da507a12a29b14e4ae5bda06b19f575a3e6079d2e2ae"
+dependencies = [
+ "bytemuck_derive",
+]
+
+[[package]]
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.77",
+]
 
 [[package]]
 name = "byteorder"
@@ -511,6 +525,12 @@ version = "0.2.3"
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 checksum = "67ba02a97a2bd10f4b59b25c7973101c79642302776489e030cd13cdab09ed15"
 
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+
 [[package]]
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@@ -708,6 +728,12 @@ version = "2.6.0"
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+
 [[package]]
 name = "deranged"
 version = "0.3.11"
@@ -793,6 +819,25 @@ dependencies = [
  "wio",
 ]
 
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56e53799688f5632f364f8fb387488dd05db9fe45db7011be066fc20e7027f8b"
+dependencies = [
+ "bytemuck",
+ "reborrow",
+]
+
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+dependencies = [
+ "bytemuck",
+]
+
 [[package]]
 name = "either"
 version = "1.13.0"
@@ -820,6 +865,58 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+ "heck",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.77",
+]
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c35da53b5a021d2484a7cc49b2ac7f2d840f8236a286f84202369bd338d761ea"
+dependencies = [
+ "equator-macro 0.2.1",
+]
+
+[[package]]
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+ "equator-macro 0.4.1",
+]
+
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.77",
+]
+
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.77",
+]
+
 [[package]]
 name = "equivalent"
 version = "1.0.1"
@@ -861,6 +958,48 @@ dependencies = [
  "zune-inflate",
 ]
 
+[[package]]
+name = "faer"
+version = "0.19.4"
+source = "git+https://github.com/sarah-ek/faer-rs?rev=4f3eb7e65c69f7f7df3bdd93aa868d5666db3656#4f3eb7e65c69f7f7df3bdd93aa868d5666db3656"
+dependencies = [
+ "bytemuck",
+ "coe-rs",
+ "dbgf",
+ "dyn-stack 0.11.0",
+ "equator 0.4.1",
+ "faer-entity",
+ "gemm",
+ "generativity",
+ "libm",
+ "matrixcompare",
+ "matrixcompare-core",
+ "nano-gemm",
+ "npyz",
+ "num-complex",
+ "num-traits",
+ "paste",
+ "rand",
+ "rand_distr",
+ "rayon",
+ "reborrow",
+ "serde",
+]
+
+[[package]]
+name = "faer-entity"
+version = "0.19.2"
+source = "git+https://github.com/sarah-ek/faer-rs?rev=4f3eb7e65c69f7f7df3bdd93aa868d5666db3656#4f3eb7e65c69f7f7df3bdd93aa868d5666db3656"
+dependencies = [
+ "bytemuck",
+ "coe-rs",
+ "libm",
+ "num-complex",
+ "num-traits",
+ "pulp",
+ "reborrow",
+]
+
 [[package]]
 name = "fallible-iterator"
 version = "0.3.0"
@@ -1103,6 +1242,130 @@ dependencies = [
  "byteorder",
 ]
 
+[[package]]
+name = "gemm"
+version = "0.18.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e400f2ffd14e7548356236c35dc39cad6666d833a852cb8a8f3f28029359bb03"
+dependencies = [
+ "dyn-stack 0.10.0",
+ "gemm-c32",
+ "gemm-c64",
+ "gemm-common",
+ "gemm-f16",
+ "gemm-f32",
+ "gemm-f64",
+ "num-complex",
+ "num-traits",
+ "paste",
+ "raw-cpuid",
+ "seq-macro",
+]
+
+[[package]]
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+dependencies = [
+ "dyn-stack 0.10.0",
+ "gemm-common",
+ "num-complex",
+ "num-traits",
+ "paste",
+ "raw-cpuid",
+ "seq-macro",
+]
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+dependencies = [
+ "dyn-stack 0.10.0",
+ "gemm-common",
+ "num-complex",
+ "num-traits",
+ "paste",
+ "raw-cpuid",
+ "seq-macro",
+]
+
+[[package]]
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+dependencies = [
+ "bytemuck",
+ "dyn-stack 0.10.0",
+ "half",
+ "num-complex",
+ "num-traits",
+ "once_cell",
+ "paste",
+ "pulp",
+ "raw-cpuid",
+ "rayon",
+ "seq-macro",
+ "sysctl",
+]
+
+[[package]]
+name = "gemm-f16"
+version = "0.18.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+dependencies = [
+ "dyn-stack 0.10.0",
+ "gemm-common",
+ "gemm-f32",
+ "half",
+ "num-complex",
+ "num-traits",
+ "paste",
+ "raw-cpuid",
+ "rayon",
+ "seq-macro",
+]
+
+[[package]]
+name = "gemm-f32"
+version = "0.18.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "acbc51c44ae3defd207e6d9416afccb3c4af1e7cef5e4960e4c720ac4d6f998e"
+dependencies = [
+ "dyn-stack 0.10.0",
+ "gemm-common",
+ "num-complex",
+ "num-traits",
+ "paste",
+ "raw-cpuid",
+ "seq-macro",
+]
+
+[[package]]
+name = "gemm-f64"
+version = "0.18.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f37fc86e325c2415a4d0cab8324a0c5371ec06fc7d2f9cb1636fcfc9536a8d8"
+dependencies = [
+ "dyn-stack 0.10.0",
+ "gemm-common",
+ "num-complex",
+ "num-traits",
+ "paste",
+ "raw-cpuid",
+ "seq-macro",
+]
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+
 [[package]]
 name = "generic-array"
 version = "0.14.7"
@@ -1202,8 +1465,10 @@ version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6dd08c532ae367adf81c312a4580bc67f1d0fe8bc9c460520283f4c0ff277888"
 dependencies = [
+ "bytemuck",
  "cfg-if",
  "crunchy",
+ "num-traits",
 ]
 
 [[package]]
@@ -1754,6 +2019,22 @@ version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0e7465ac9959cc2b1404e8e2367b43684a6d13790fe23056cc8c6c5a6b7bcb94"
 
+[[package]]
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+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37832ba820e47c93d66b4360198dccb004b43c74abc3ac1ce1fed54e65a80445"
+dependencies = [
+ "matrixcompare-core",
+ "num-traits",
+]
+
+[[package]]
+name = "matrixcompare-core"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b0bdabb30db18805d5290b3da7ceaccbddba795620b86c02145d688e04900a73"
+
 [[package]]
 name = "matrixmultiply"
 version = "0.3.9"
@@ -1862,6 +2143,76 @@ dependencies = [
  "typenum",
 ]
 
+[[package]]
+name = "nano-gemm"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f563548d38f390ef9893e4883ec38c1fb312f569e98d76bededdd91a3b41a043"
+dependencies = [
+ "equator 0.2.2",
+ "nano-gemm-c32",
+ "nano-gemm-c64",
+ "nano-gemm-codegen",
+ "nano-gemm-core",
+ "nano-gemm-f32",
+ "nano-gemm-f64",
+ "num-complex",
+]
+
+[[package]]
+name = "nano-gemm-c32"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a40449e57a5713464c3a1208c4c3301c8d29ee1344711822cf022bc91373a91b"
+dependencies = [
+ "nano-gemm-codegen",
+ "nano-gemm-core",
+ "num-complex",
+]
+
+[[package]]
+name = "nano-gemm-c64"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "743a6e6211358fba85d1009616751e4107da86f4c95b24e684ce85f25c25b3bf"
+dependencies = [
+ "nano-gemm-codegen",
+ "nano-gemm-core",
+ "num-complex",
+]
+
+[[package]]
+name = "nano-gemm-codegen"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "963bf7c7110d55430169dc74c67096375491ed580cd2ef84842550ac72e781fa"
+
+[[package]]
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+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fe3fc4f83ae8861bad79dc3c016bd6b0220da5f9de302e07d3112d16efc24aa6"
+
+[[package]]
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+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e3681b7ce35658f79da94b7f62c60a005e29c373c7111ed070e3bf64546a8bb"
+dependencies = [
+ "nano-gemm-codegen",
+ "nano-gemm-core",
+]
+
+[[package]]
+name = "nano-gemm-f64"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bc1e619ed04d801809e1f63e61b669d380c4119e8b0cdd6ed184c6b111f046d8"
+dependencies = [
+ "nano-gemm-codegen",
+ "nano-gemm-core",
+]
+
 [[package]]
 name = "native-tls"
 version = "0.2.12"
@@ -1901,6 +2252,17 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0676bb32a98c1a483ce53e500a81ad9c3d5b3f7c920c28c24e9cb0980d0b5bc8"
 
+[[package]]
+name = "npyz"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13f27ea175875c472b3df61ece89a6d6ef4e0627f43704e400c782f174681ebd"
+dependencies = [
+ "byteorder",
+ "num-bigint",
+ "py_literal",
+]
+
 [[package]]
 name = "num"
 version = "0.4.3"
@@ -1931,7 +2293,9 @@ version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "73f88a1307638156682bada9d7604135552957b7818057dcef22705b4d509495"
 dependencies = [
+ "bytemuck",
  "num-traits",
+ "rand",
 ]
 
 [[package]]
@@ -2114,6 +2478,51 @@ version = "2.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e3148f5046208a5d56bcfc03053e3ca6334e51da8dfb19b6cdc8b306fae3283e"
 
+[[package]]
+name = "pest"
+version = "2.7.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fdbef9d1d47087a895abd220ed25eb4ad973a5e26f6a4367b038c25e28dfc2d9"
+dependencies = [
+ "memchr",
+ "thiserror",
+ "ucd-trie",
+]
+
+[[package]]
+name = "pest_derive"
+version = "2.7.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4d3a6e3394ec80feb3b6393c725571754c6188490265c61aaf260810d6b95aa0"
+dependencies = [
+ "pest",
+ "pest_generator",
+]
+
+[[package]]
+name = "pest_generator"
+version = "2.7.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94429506bde1ca69d1b5601962c73f4172ab4726571a59ea95931218cb0e930e"
+dependencies = [
+ "pest",
+ "pest_meta",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.77",
+]
+
+[[package]]
+name = "pest_meta"
+version = "2.7.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac8a071862e93690b6e34e9a5fb8e33ff3734473ac0245b27232222c4906a33f"
+dependencies = [
+ "once_cell",
+ "pest",
+ "sha2",
+]
+
 [[package]]
 name = "pin-project"
 version = "1.1.5"
@@ -2302,6 +2711,31 @@ dependencies = [
  "unicase",
 ]
 
+[[package]]
+name = "pulp"
+version = "0.18.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a0a01a0dc67cf4558d279f0c25b0962bd08fc6dec0137699eae304103e882fe6"
+dependencies = [
+ "bytemuck",
+ "libm",
+ "num-complex",
+ "reborrow",
+]
+
+[[package]]
+name = "py_literal"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "102df7a3d46db9d3891f178dcc826dc270a6746277a9ae6436f8d29fd490a8e1"
+dependencies = [
+ "num-bigint",
+ "num-complex",
+ "num-traits",
+ "pest",
+ "pest_derive",
+]
+
 [[package]]
 name = "qoi"
 version = "0.4.1"
@@ -2437,6 +2871,15 @@ dependencies = [
  "rgb",
 ]
 
+[[package]]
+name = "raw-cpuid"
+version = "10.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c297679cb867470fa8c9f67dbba74a78d78e3e98d7cf2b08d6d71540f797332"
+dependencies = [
+ "bitflags 1.3.2",
+]
+
 [[package]]
 name = "rawpointer"
 version = "0.2.1"
@@ -2463,6 +2906,12 @@ dependencies = [
  "crossbeam-utils",
 ]
 
+[[package]]
+name = "reborrow"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "03251193000f4bd3b042892be858ee50e8b3719f2b08e5833ac4353724632430"
+
 [[package]]
 name = "redox_syscall"
 version = "0.5.4"
@@ -2868,6 +3317,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "seq-macro"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a3f0bf26fd526d2a95683cd0f87bf103b8539e2ca1ef48ce002d67aad59aa0b4"
+
 [[package]]
 name = "serde"
 version = "1.0.210"
@@ -3035,6 +3490,7 @@ dependencies = [
  "chrono",
  "clap",
  "discord-rich-presence",
+ "faer",
  "freetype-rs",
  "hypertesseract",
  "image 0.25.2",
@@ -3200,6 +3656,20 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "sysctl"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec7dddc5f0fee506baf8b9fdb989e242f17e4b11c61dfbb0635b705217199eea"
+dependencies = [
+ "bitflags 2.6.0",
+ "byteorder",
+ "enum-as-inner",
+ "libc",
+ "thiserror",
+ "walkdir",
+]
+
 [[package]]
 name = "system-configuration"
 version = "0.5.1"
@@ -3658,6 +4128,12 @@ dependencies = [
  "syn 2.0.77",
 ]
 
+[[package]]
+name = "ucd-trie"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2896d95c02a80c6d6a5d6e953d479f5ddf2dfdb6a244441010e373ac0fb88971"
+
 [[package]]
 name = "unicase"
 version = "2.7.0"

Cargo.toml

@@ -52,6 +52,13 @@ axum = { version = "0.7.6", features = ["macros"] }
 paste = "1.0.15"
 discord-rich-presence = "0.2.4"
 reqwest = { version = "0.12.7", features = ["json"] }
+faer = { git = "https://github.com/sarah-ek/faer-rs", rev = "4f3eb7e65c69f7f7df3bdd93aa868d5666db3656", features = ["serde"] }
 
-# [profile.dev.package."*"]
+[profile.dev.package.imageproc]
-# opt-level = 3
+opt-level = 3
+
+[profile.dev.package.image]
+opt-level = 3
+
+[profile.dev.package.faer]
+opt-level = 3

README.md

@@ -77,7 +77,9 @@ Additionally, you must place a custom `b30` background at `$SHIMMERING_ASSET_DIR
 After everything has been placed in the right directory, run `shimmeringmoon-cli prepare-jackets` to prepare everything. This will:
 
 - Associate each asset with it's database ID
-- Build out a recognition matrix for image recognition purposes (this matrix more or less contains a 8x8 downscaled version of each provided asset, stored in bitmap format together with the associated database ID)
+- Build out a recognition matrix (~30kb) for image recognition purposes. This file contains:
+  - about ~3 pixels worth of information for each jacket, stored together with their associated database IDs
+  - a projection matrix which transforms a $8 \times 8$ downscaled vectorized version of an image (that's $192$ dimensions — $64 \text{pixels} \times 3 \text{channels}$) and projects it to a $10$-dimensional space (the matrix is built using [singular value decomposition](https://en.wikipedia.org/wiki/Singular_value_decomposition)).
 
 ### Importing charts
 

flake.nix

@@ -21,7 +21,7 @@
         # };
         # toolchain = pkgs.rust-bin.selectLatestNightlyWith (toolchain: toolchain.default);
         # toolchain = pkgs.rust-bin.stable.latest.default;
-        # toolchain = inputs.fenix.packages.${system}.complete.toolchain;
+        toolchain = inputs.fenix.packages.${system}.complete.toolchain;
         spkgs = inputs.self.packages.${system};
         inherit (pkgs) lib;
       in
@@ -46,11 +46,12 @@
         #  {{{ Devshell
         devShell = pkgs.mkShell rec {
           nativeBuildInputs = with pkgs; [
-            cargo
+            # cargo
-            rustc
+            # rustc
-            clippy
+            # clippy
-            rust-analyzer
+            # rust-analyzer
-            rustfmt
+            # rustfmt
+            toolchain
 
             ruff
             imagemagick

shimmering/config/shorthands.csv

@@ -11,6 +11,7 @@ Kanbu de Tomatte Sugu Tokeru,,,overdrive
 1F√,,,onefr
 [X],,,infinity
 0xe0e1ccull,,,ifirmx
+Last,,,last
 Last | Moment,,,last
 Last | Eternity,,,lasteternity
 Lost Emotion feat. nomico,,,lostemotion
@@ -53,9 +54,11 @@ Einherjar Joker,,,einherjar
 GOODTEK (Arcaea Edit),,,goodtek
 Kanagawa Cyber Culvert,,,kanagawa
 La'qryma of the Wasteland,,,laqryma
+PRAGMATISM,,,pragmatism
 PRAGMATISM -RESURRECTION-,,,pragmatism
 qualia -ideaesthesia-,,,qualia
 Shades of Light in a Transcendent Realm,,,shadesoflight
 trappola bewitching,,,trappola
+Vicious Heroism,,,viciousheroism
 Vicious [ANTi] Heroism,,,viciousheroism
 eden,,,edenwacca

src/arcaea/jacket.rs

@@ -2,13 +2,13 @@
 use std::fs;
 
 use anyhow::Context;
-use image::{imageops::FilterType, GenericImageView, Rgba};
+use faer::{Mat, MatRef};
-use num::Integer;
+use image::{GenericImageView, Pixel};
+use num::{Integer, ToPrimitive};
 use serde::{Deserialize, Serialize};
-use serde_with::serde_as;
 
 use crate::arcaea::chart::{Difficulty, Jacket, SongCache};
-use crate::assets::{get_asset_dir, should_skip_jacket_art};
+use crate::assets::get_asset_dir;
 use crate::context::Error;
 // }}}
 
@@ -16,19 +16,12 @@ use crate::context::Error;
 pub const SPLIT_FACTOR: u32 = 8;
 pub const IMAGE_VEC_DIM: usize = (SPLIT_FACTOR * SPLIT_FACTOR * 3) as usize;
 pub const BITMAP_IMAGE_SIZE: u32 = 174;
+pub const JACKET_RECOGNITITION_DIMENSIONS: usize = 10;
 
-#[serde_as]
+// {{{ (Image => vector) encoding
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[allow(clippy::identity_op)]
-pub struct ImageVec {
+pub fn image_to_vec(image: &impl GenericImageView) -> MVec<f32> {
-	#[serde_as(as = "[_; IMAGE_VEC_DIM]")]
+	let mut colors = MVec::zeros(IMAGE_VEC_DIM, 1);
-	pub colors: [f32; IMAGE_VEC_DIM],
-}
-
-impl ImageVec {
-	// {{{ (Image => vector) encoding
-	#[allow(clippy::identity_op)]
-	pub fn from_image(image: &impl GenericImageView<Pixel = Rgba<u8>>) -> Self {
-		let mut colors = [0.0; IMAGE_VEC_DIM];
 	let chunk_width = image.width() / SPLIT_FACTOR;
 	let chunk_height = image.height() / SPLIT_FACTOR;
 	for i in 0..(SPLIT_FACTOR * SPLIT_FACTOR) {
@@ -46,9 +39,13 @@ impl ImageVec {
 		let mut count = 0;
 
 		for (_, _, pixel) in cropped.pixels() {
-				r += (pixel.0[0] as u64).pow(2);
+			let channels = pixel.channels();
-				g += (pixel.0[1] as u64).pow(2);
+
-				b += (pixel.0[2] as u64).pow(2);
+			// I'm not sure this does what it's supposed to do for non rgb(a) pixels...
+			r += channels[0].to_u64().unwrap().pow(2);
+			g += channels[1].to_u64().unwrap().pow(2);
+			b += channels[2].to_u64().unwrap().pow(2);
+
 			count += 1;
 		}
 
@@ -56,75 +53,50 @@ impl ImageVec {
 		let r = (r as f64 / count).sqrt();
 		let g = (g as f64 / count).sqrt();
 		let b = (b as f64 / count).sqrt();
-			colors[i as usize * 3 + 0] = r as f32;
+		colors[(i as usize * 3 + 0, 0)] = r as f32;
-			colors[i as usize * 3 + 1] = g as f32;
+		colors[(i as usize * 3 + 1, 0)] = g as f32;
-			colors[i as usize * 3 + 2] = b as f32;
+		colors[(i as usize * 3 + 2, 0)] = b as f32;
 	}
 
-		Self { colors }
+	colors
-	}
-
-	#[inline]
-	pub fn distance_squared_to(&self, other: &Self) -> f32 {
-		let mut total = 0.0;
-
-		for i in 0..IMAGE_VEC_DIM {
-			let d = self.colors[i] - other.colors[i];
-			total += d * d;
-		}
-
-		total
-	}
-	// }}}
 }
+// }}}
 
-#[derive(Clone)]
+/// A column vector
+pub type MVec<T> = Mat<T>;
+
+/// This struct holds:
+/// - a set of (song_id, vec) pairs of different images projected through the
+///   aforementioned transform.
+/// - an projection matrix for dimensionality reduction
+#[derive(Clone, Serialize, Deserialize)]
 pub struct JacketCache {
-	jackets: Vec<(u32, ImageVec)>,
+	/// A matrix with each column corresponding to the result of passing a jacket
+	/// through [[image_to_vec]], and then projecting it through `transform_matrix`
+	pub jacket_matrix: Mat<f32>,
+
+	/// Assigns each column of `jacket_matrix` a song id.
+	pub jacket_ids: Vec<u32>,
+
+	/// A projection matrix for dimensionality reduction.
+	pub transform_matrix: Mat<f32>,
 }
 
-impl JacketCache {
+// {{{ Read jackets
-	// {{{ Generate
+pub fn read_jackets(song_cache: &mut SongCache) -> Result<(), Error> {
-	// This is a bit inefficient (using a hash set), but only runs once
-	pub fn new(song_cache: &mut SongCache) -> Result<Self, Error> {
-		let jacket_vectors = if should_skip_jacket_art() {
-			let path = get_asset_dir().join("placeholder_jacket.jpg");
-			let contents: &'static _ = fs::read(path)?.leak();
-			let image = image::load_from_memory(contents)?;
-			let bitmap: &'static _ = Box::leak(Box::new(
-				image
-					.resize(BITMAP_IMAGE_SIZE, BITMAP_IMAGE_SIZE, FilterType::Nearest)
-					.into_rgb8(),
-			));
-
-			for chart in song_cache.charts_mut() {
-				chart.cached_jacket = Some(Jacket {
-					raw: contents,
-					bitmap,
-				});
-			}
-
-			Vec::new()
-		} else {
 	let suffix = format!("_{BITMAP_IMAGE_SIZE}.jpg");
 	let songs_dir = get_asset_dir().join("songs/by_id");
-			let entries =
+	let entries = fs::read_dir(songs_dir).with_context(|| "Couldn't read songs directory")?;
-				fs::read_dir(songs_dir).with_context(|| "Couldn't read songs directory")?;
-			let bytes = fs::read(get_asset_dir().join("songs/recognition_matrix"))
-				.with_context(|| "Could not read jacket recognition matrix")?;
-			let jacket_vectors = postcard::from_bytes(&bytes)
-				.with_context(|| "Could not decode jacket recognition matrix")?;
 
 	for entry in entries {
 		let dir = entry?;
 		let raw_dir_name = dir.file_name();
 		let dir_name = raw_dir_name.to_str().unwrap();
-				let song_id = dir_name.parse().with_context(|| {
+		let song_id = dir_name
-					format!("Dir name {dir_name} could not be parsed as `u32` song id")
+			.parse()
-				})?;
+			.with_context(|| format!("Dir name {dir_name} could not be parsed as `u32` song id"))?;
 
-				let entries =
+		let entries = fs::read_dir(dir.path()).with_context(|| "Couldn't read song directory")?;
-					fs::read_dir(dir.path()).with_context(|| "Couldn't read song directory")?;
 		for entry in entries {
 			let file = entry?;
 			let raw_name = file.file_name();
@@ -172,28 +144,42 @@ impl JacketCache {
 		}
 	}
 
-			jacket_vectors
+	Ok(())
-		};
+}
+// }}}
 
-		let result = Self {
+impl JacketCache {
-			jackets: jacket_vectors,
+	// {{{ Generate
-		};
+	pub fn new() -> Result<Self, Error> {
+		let bytes = fs::read(get_asset_dir().join("songs/recognition_matrix"))
+			.with_context(|| "Could not read jacket recognition matrix")?;
+
+		let result = postcard::from_bytes(&bytes)?;
+		// .with_context(|| "Could not decode jacket recognition matrix")?;
 
 		Ok(result)
 	}
 	// }}}
 	// {{{ Recognise
+	/// Transforms a vector from image space to recognition space.
 	#[inline]
-	pub fn recognise(
+	pub fn transform_vec(&self, vec: MatRef<f32>) -> MVec<f32> {
-		&self,
+		&self.transform_matrix * vec
-		image: &impl GenericImageView<Pixel = Rgba<u8>>,
+	}
-	) -> Option<(f32, &u32)> {
+
-		let vec = ImageVec::from_image(image);
+	#[inline]
-		self.jackets
+	pub fn recognise(&self, image: &impl GenericImageView) -> Option<(f32, u32)> {
+		let vec = self.transform_vec(image_to_vec(image).as_ref());
+		self.jacket_ids
 			.iter()
-			.map(|(i, v)| (i, v, v.distance_squared_to(&vec)))
+			.enumerate()
-			.min_by(|(_, _, d1), (_, _, d2)| d1.partial_cmp(d2).expect("NaN distance encountered"))
+			.map(|(idx, id)| {
-			.map(|(i, _, d)| (d.sqrt(), i))
+				(id, {
+					(self.jacket_matrix.subcols(idx, 1) - &vec).squared_norm_l2()
+				})
+			})
+			.min_by(|(_, d1), (_, d2)| d1.partial_cmp(d2).expect("NaN distance encountered"))
+			.map(|(i, d)| (d.sqrt(), *i))
 	}
 	// }}}
 }

src/assets.rs

@@ -71,11 +71,6 @@ pub static UNI_FONT: RefCell<Face> = get_font("unifont.otf");
 }
 // }}}
 // {{{ Asset art helpers
-#[inline]
-pub fn should_skip_jacket_art() -> bool {
-	var("SHIMMERING_NO_JACKETS").unwrap_or_default() == "1"
-}
-
 #[inline]
 #[allow(dead_code)]
 pub fn should_blur_jacket_art() -> bool {

src/bin/cli/commands/prepare_jackets.rs

@@ -3,10 +3,14 @@ use std::fs;
 use std::io::{stdout, Write};
 
 use anyhow::{anyhow, bail, Context};
+use faer::Mat;
 use image::imageops::FilterType;
 
 use shimmeringmoon::arcaea::chart::{Difficulty, SongCache};
-use shimmeringmoon::arcaea::jacket::{ImageVec, BITMAP_IMAGE_SIZE};
+use shimmeringmoon::arcaea::jacket::{
+	image_to_vec, read_jackets, JacketCache, BITMAP_IMAGE_SIZE, IMAGE_VEC_DIM,
+	JACKET_RECOGNITITION_DIMENSIONS,
+};
 use shimmeringmoon::assets::{get_asset_dir, get_data_dir};
 use shimmeringmoon::context::{connect_db, Error};
 use shimmeringmoon::recognition::fuzzy_song_name::guess_chart_name;
@@ -20,8 +24,12 @@ fn clear_line() {
 
 pub fn run() -> Result<(), Error> {
 	let db = connect_db(&get_data_dir());
-	let song_cache = SongCache::new(&db)?;
+	let mut song_cache = SongCache::new(&db)?;
 
+	let mut jacket_vector_ids = vec![];
+	let mut jacket_vectors = vec![];
+
+	// {{{ Prepare directories
 	let songs_dir = get_asset_dir().join("songs");
 	let raw_songs_dir = songs_dir.join("raw");
 
@@ -30,9 +38,8 @@ pub fn run() -> Result<(), Error> {
 		fs::remove_dir_all(&by_id_dir).with_context(|| "Could not remove `by_id` dir")?;
 	}
 	fs::create_dir_all(&by_id_dir).with_context(|| "Could not create `by_id` dir")?;
-
+	// }}}
-	let mut jacket_vectors = vec![];
+	// {{{ Traverse raw songs directory
-
 	let entries = fs::read_dir(&raw_songs_dir)
 		.with_context(|| "Couldn't read songs directory")?
 		.collect::<Result<Vec<_>, _>>()
@@ -84,12 +91,7 @@ pub fn run() -> Result<(), Error> {
 			// the same directory. To do this, we only allow the base jacket to refer
 			// to the FUTURE difficulty, unless it's the only jacket present
 			// (or unless we are parsing the tutorial)
-			let search_difficulty =
+			let search_difficulty = difficulty;
-				if entries.len() > 1 && difficulty.is_none() && dir_name != "tutorial" {
-					Some(Difficulty::FTR)
-				} else {
-					difficulty
-				};
 
 			let (song, _) = guess_chart_name(dir_name, &song_cache, search_difficulty, true)
 				.with_context(|| format!("Could not recognise chart name from '{dir_name}'"))?;
@@ -120,12 +122,12 @@ pub fn run() -> Result<(), Error> {
 				.with_context(|| format!("Could not read image for file {:?}", file.path()))?
 				.leak();
 			let image = image::load_from_memory(contents)?;
-
-			jacket_vectors.push((song.id, ImageVec::from_image(&image)));
-
 			let small_image =
 				image.resize(BITMAP_IMAGE_SIZE, BITMAP_IMAGE_SIZE, FilterType::Gaussian);
 
+			jacket_vector_ids.push(song.id);
+			jacket_vectors.push(image_to_vec(&image));
+
 			{
 				let image_small_path =
 					out_dir.join(format!("{difficulty_string}_{BITMAP_IMAGE_SIZE}.jpg"));
@@ -150,27 +152,100 @@ pub fn run() -> Result<(), Error> {
 			}
 		}
 	}
+	// }}}
 
 	clear_line();
+	println!("Successfully processed jackets");
 
-	// NOTE: this is N^2, but it's a one-off warning thing, so it's fine
+	read_jackets(&mut song_cache)?;
+	println!("Successfully read jackets");
+
+	// {{{ Warn on missing jackets
 	for chart in song_cache.charts() {
-		if jacket_vectors.iter().all(|(i, _)| chart.song_id != *i) {
+		if chart.cached_jacket.is_none() {
 			println!(
 				"No jacket found for '{} [{:?}]'",
-				song_cache.lookup_song(chart.song_id)?.song.title,
+				song_cache.lookup_song(chart.song_id)?.song,
 				chart.difficulty
 			)
 		}
 	}
 
+	println!("No missing jackets detected");
+	// }}}
+	// {{{ Compute jacket vec matrix
+	let mut jacket_matrix: Mat<f32> = Mat::zeros(IMAGE_VEC_DIM, jacket_vectors.len());
+
+	for (i, v) in jacket_vectors.iter().enumerate() {
+		jacket_matrix.subcols_mut(i, 1).copy_from(v);
+	}
+	// }}}
+	// {{{ Compute transform matrix
+	let transform_matrix = {
+		let svd = jacket_matrix.thin_svd();
+
+		svd.u()
+			.transpose()
+			.submatrix(0, 0, JACKET_RECOGNITITION_DIMENSIONS, IMAGE_VEC_DIM)
+			.to_owned()
+	};
+	// }}}
+	// {{{ Build jacket cache
+	let jacket_cache = JacketCache {
+		jacket_ids: jacket_vector_ids,
+		jacket_matrix: &transform_matrix * &jacket_matrix,
+		transform_matrix,
+	};
+	// }}}
+
+	// {{{ Perform jacket recognition test
+	let chart_count = song_cache.charts().count();
+	for (i, chart) in song_cache.charts().enumerate() {
+		let song = &song_cache.lookup_song(chart.song_id)?.song;
+
+		// {{{ Update console display
+		if i != 0 {
+			clear_line();
+		}
+
+		print!("{}/{}: {song}", i, chart_count);
+
+		if i % 5 == 0 {
+			stdout().flush()?;
+		}
+		// }}}
+
+		if let Some(jacket) = chart.cached_jacket {
+			if let Some((_, song_id)) = jacket_cache.recognise(jacket.bitmap) {
+				if song_id != song.id {
+					let mistake = &song_cache.lookup_song(song_id)?.song;
+					bail!(
+						"Could not recognise jacket for {song} [{}]. Found song {mistake} instead.",
+						chart.difficulty
+					)
+				}
+			} else {
+				bail!(
+					"Could not recognise jacket for {song} [{}].",
+					chart.difficulty
+				)
+			}
+		}
+	}
+	// }}}
+
+	clear_line();
+	println!("Successfully tested jacket recognition");
+
+	// {{{ Save recognition matrix to disk
 	{
 		println!("Encoded {} images", jacket_vectors.len());
-		let bytes = postcard::to_allocvec(&jacket_vectors)
+		let bytes = postcard::to_allocvec(&jacket_cache)
 			.with_context(|| "Coult not encode jacket matrix")?;
 		fs::write(songs_dir.join("recognition_matrix"), bytes)
 			.with_context(|| "Could not write jacket matrix")?;
 	}
+	// }}}
 
 	Ok(())
 }

src/context.rs

@@ -7,6 +7,7 @@ use std::fs;
 use std::path::Path;
 use std::sync::LazyLock;
 
+use crate::arcaea::jacket::read_jackets;
 use crate::arcaea::{chart::SongCache, jacket::JacketCache};
 use crate::assets::{get_data_dir, EXO_FONT, GEOSANS_FONT, KAZESAWA_BOLD_FONT, KAZESAWA_FONT};
 use crate::recognition::{hyperglass::CharMeasurements, ui::UIMeasurements};
@@ -109,7 +110,10 @@ impl UserContext {
 
 			let mut song_cache = SongCache::new(&db)?;
 			let ui_measurements = UIMeasurements::read()?;
-			let jacket_cache = timed!("make_jacket_cache", { JacketCache::new(&mut song_cache)? });
+			let jacket_cache = JacketCache::new()?;
+			timed!("read_jackets", {
+				read_jackets(&mut song_cache)?;
+			});
 
 			// {{{ Font measurements
 			static WHITELIST: &str = "0123456789'abcdefghklmnopqrstuvwxyzABCDEFGHIJKLMNOPRSTUVWXYZ";

src/recognition/recognize.rs

@@ -327,7 +327,7 @@ impl ImageAnalyzer {
 			bail!("No known jacket looks like this");
 		}
 
-		let (song, chart) = ctx.song_cache.lookup_by_difficulty(*song_id, difficulty)?;
+		let (song, chart) = ctx.song_cache.lookup_by_difficulty(song_id, difficulty)?;
 
 		Ok((song, chart))
 	}