Byakuren

Byakuren is a C library for extracting theme colors from images.

‍This library has been used in production by a related company for years.

‍TODO: Implement KD-Tree for color finding.

聖 白蓮

‍聖 白蓮（ひじり びゃくれん，Hiziri Byakuren）是系列作品《东方project》中的角色，首次登场于《东方星莲船》。

• 种族：魔法使
• 能力：使用魔法程度的能力（酣畅增强身体能力的）
• 危险度：不明
• 人类友好度：中
• 主要活动场所：命莲寺之类

命莲寺的住持。虽然原本是人类，不过由于常年的修行已经完全超越了人类。现在已经属于人们常说的魔法使了。

虽然已经入了佛门，但是不知道什么原因却被妖怪敬仰着。她从来没有像童话故事中的魔法使那样，念诵着咒语治退妖怪。使用的力量完全是邪恶的，一点都不像是圣人，虽然并没有人目击到她与人类为敌，但其实已彻底成为妖怪的同伴了。

Features

• Supports multiple color extraction algorithms:
  • Octree algorithm
  • Min-diff algorithm
  • Mix-in algorithm (combining Octree and Min-diff)
• Provides a simple C API
• Can be compiled into a static library for easy integration

Installation

Clone the repository with submodules:

git clone --recurse-submodules https://github.com/XadillaX/byakuren.git

Compile the static library:

make byakuren

After compilation, include byakuren.h in your project to use the library:

#include "byakuren.h"

Usage

1. Initialize the Byakuren environment:

int result = bkr_init();

1. Use one of the color extraction algorithms:
   • Octree Algorithm
   • Min-diff Algorithm
   • Mix Algorithm
2. Release the environment when done:

bkr_destroy();

For detailed API usage, refer to the API Documentation section below.

Testing

Compile the test binary:

make ./test/bkr_test

Run the test with a specific algorithm:

cd test && ./bkr_test ALGORITHM

Replace ALGORITHM with octree, mindiff, or mix.

Test Helper

A Node.js-based test helper is available for quick testing without generating .rgb files manually.

1. Install dependencies:

npm install

1. Run the helper:

./test/run.js -u IMAGE_URL -a ALGORITHM

For example:

./test/run.js -u http://example.com/image.jpg -a octree

Use -a all to test all three algorithms at once.

APIs

Here's a brief overview of the main APIs provided by Byakuren. For detailed parameter descriptions and usage, please refer to the full API documentation in the header files.

Initialization & Cleanup

int bkr_init();
void bkr_destroy();

Octree Algorithm

bkr_octree_node* bkr_build_octree(bkr_rgb* pixels, uint32_t pixel_count, uint32_t max_colors);
int bkr_octree_calculate_color_stats(bkr_octree_node* node, bkr_color_stats stats[]);
void bkr_release_octree(bkr_octree_node* node);

Min-diff Algorithm

int bkr_mindiff_calculate_color_stats(bkr_rgb* pixels, uint32_t pixel_count, bkr_color_stats stats[], bkr_mindiff_parameter* param);

Mix Algorithm

int bkr_mix_calculate_color_stats(bkr_rgb* pixels, uint32_t pixel_count, uint32_t octree_max_colors, bkr_mindiff_parameter* mindiff_param, bkr_color_stats stats[]);

For full API documentation, including detailed descriptions of parameters and return values, please refer to the following header files:

• bkr_common.h: Common structures and definitions
• lib/octree.h: Octree algorithm functions
• lib/mindiff.h: Min-diff algorithm functions
• lib/mix.h: Mix algorithm functions

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

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