A lightweight, pure C implementation of a JPEG encoder designed for embedded systems. No external dependencies except the standard C library.
- ✅ Pure C99 - No external dependencies
- ✅ Multiple input formats - RGB, YUV420 planar, UYVY packed
- ✅ SIMD optimized - ARM NEON, AArch64, MIPS MSA, x86 SSE/AVX
- ✅ Baseline JPEG - Complete encoding pipeline
- ✅ RGB565 decoder - Decode to embedded display format
- ✅ 4:2:0 subsampling - Standard chroma subsampling
- ✅ Configurable quality - 1-100 quality parameter
- ✅ Low memory footprint - Suitable for embedded systems
- ✅ C++ compatible - Extern "C" linkage
# Default build (no SIMD)
make
# ARM NEON optimization
make ARCH=arm
# AArch64 optimization
make ARCH=aarch64
# MIPS MSA optimization
make ARCH=mips
# x86 SSE2 optimization
make ARCH=x86
# x86 AVX2 optimization
make ARCH=x86_avx# RGB encoding
./build/jpeg_example 640 480 85
# YUV420 encoding
./build/jpeg_example_yuv 640 480 85
# UYVY encoding
./build/jpeg_example_uyvy 640 480 85
# JPEG decoding
./build/jpeg_example_decode input.jpg#include "jpeg_encoder.h"
uint8_t *rgb_data = ...; // width * height * 3 bytes
uint8_t *jpeg_data = NULL;
size_t jpeg_size = 0;
int result = jpeg_encode_rgb(rgb_data, 640, 480, 85, &jpeg_data, &jpeg_size);
if (result == 0) {
FILE *fp = fopen("output.jpg", "wb");
fwrite(jpeg_data, 1, jpeg_size, fp);
fclose(fp);
jpeg_free(jpeg_data);
}uint8_t *y_plane = ...; // width * height
uint8_t *u_plane = ...; // (width/2) * (height/2)
uint8_t *v_plane = ...; // (width/2) * (height/2)
int result = jpeg_encode_yuv420(y_plane, u_plane, v_plane,
640, 480, 85, &jpeg_data, &jpeg_size);uint8_t *uyvy_data = ...; // width * height * 2 bytes
int result = jpeg_encode_uyvy(uyvy_data, 640, 480, 85, &jpeg_data, &jpeg_size);#include "jpeg_decoder.h"
uint8_t *jpeg_data = ...; // JPEG file data
size_t jpeg_size = ...; // JPEG file size
uint16_t *rgb565 = NULL;
int width, height;
int result = jpeg_decode_rgb565(jpeg_data, jpeg_size, &rgb565, &width, &height);
if (result == 0) {
// Use RGB565 data (16-bit per pixel)
jpeg_decoder_free(rgb565);
}- 📖 API Documentation - Detailed API reference
- 🤝 Contributing Guide - How to contribute
- Color space conversion - RGB → YCbCr
- Chroma subsampling - 4:2:0 (4 Y blocks, 1 Cb, 1 Cr per 16×16 MCU)
- DCT transform - 8×8 block Discrete Cosine Transform
- Quantization - Standard tables scaled by quality
- Zig-zag scan - Convert 8×8 to 1D sequence
- Huffman coding - Entropy encoding with standard tables
- Encoder structure: ~200 bytes
- Output buffer: Initial 64KB, grows as needed
- Working memory: ~2KB per MCU
- SIMD provides 2-4× speedup
- Typical encoding: 640×480 @ 85 quality ≈ 50-100KB output
- Embedded systems: Tested on ARM Cortex-A series
- Baseline JPEG only (no progressive)
- Fixed 4:2:0 chroma subsampling
- Standard Huffman tables (not optimized per image)
- No EXIF metadata support
See LICENSE file for details.
Contributions are welcome! Please read docs/CONTRIBUTING.md first.
适用于嵌入式系统的轻量级JPEG编码器，纯C实现，无第三方库依赖。
- ✅ 纯C99实现 - 无外部依赖（仅需标准C库）
- ✅ 多种输入格式 - 支持RGB、YUV420平面、UYVY打包
- ✅ SIMD优化 - 支持ARM NEON、AArch64、MIPS MSA、x86 SSE/AVX
- ✅ 完整JPEG编码 - 实现基线JPEG编码流程
- ✅ RGB565解码器 - 解码为嵌入式显示格式
- ✅ 4:2:0子采样 - 标准色度子采样
- ✅ 可配置质量 - 质量参数1-100
- ✅ 低内存占用 - 适合嵌入式系统
- ✅ C++兼容 - 支持extern "C"链接
# 默认编译（无SIMD优化）
make
# ARM NEON优化
make ARCH=arm
# AArch64优化
make ARCH=aarch64
# MIPS MSA优化
make ARCH=mips
# x86 SSE2优化
make ARCH=x86
# x86 AVX2优化
make ARCH=x86_avx# RGB编码
./build/jpeg_example 640 480 85
# YUV420编码
./build/jpeg_example_yuv 640 480 85
# UYVY编码
./build/jpeg_example_uyvy 640 480 85
# JPEG解码
./build/jpeg_example_decode input.jpg#include "jpeg_encoder.h"
// 准备RGB数据（每像素3字节：R,G,B）
uint8_t *rgb_data = ...; // width * height * 3 字节
uint8_t *jpeg_data = NULL;
size_t jpeg_size = 0;
int result = jpeg_encode_rgb(rgb_data, 640, 480, 85, &jpeg_data, &jpeg_size);
if (result == 0) {
FILE *fp = fopen("output.jpg", "wb");
fwrite(jpeg_data, 1, jpeg_size, fp);
fclose(fp);
jpeg_free(jpeg_data);
}// 准备YUV420数据
uint8_t *y_plane = ...; // width * height 字节
uint8_t *u_plane = ...; // (width/2) * (height/2) 字节
uint8_t *v_plane = ...; // (width/2) * (height/2) 字节
int result = jpeg_encode_yuv420(y_plane, u_plane, v_plane,
640, 480, 85, &jpeg_data, &jpeg_size);// 准备UYVY数据（YUV422打包格式）
uint8_t *uyvy_data = ...; // width * height * 2 字节
int result = jpeg_encode_uyvy(uyvy_data, 640, 480, 85, &jpeg_data, &jpeg_size);#include "jpeg_decoder.h"
// 准备JPEG数据
uint8_t *jpeg_data = ...; // JPEG文件数据
size_t jpeg_size = ...; // JPEG文件大小
uint16_t *rgb565 = NULL;
int width, height;
int result = jpeg_decode_rgb565(jpeg_data, jpeg_size, &rgb565, &width, &height);
if (result == 0) {
// 使用RGB565数据（16位/像素）
jpeg_decoder_free(rgb565);
}- 颜色空间转换 - RGB → YCbCr
- 色度子采样 - 4:2:0（每个16x16 MCU包含4个Y块，1个Cb块，1个Cr块）
- DCT变换 - 8x8块的离散余弦变换
- 量化 - 使用标准量化表，根据质量参数缩放
- Zig-zag扫描 - 将8x8块转换为1D序列
- 霍夫曼编码 - 使用标准霍夫曼表进行熵编码
- 编码器结构：约200字节
- 输出缓冲区：初始64KB，按需增长
- 临时工作内存：每个MCU约2KB
- SIMD优化提供2-4倍加速
- 典型编码：640×480 @ 85质量 ≈ 50-100KB输出
- 嵌入式系统：已在ARM Cortex-A系列测试
- 仅支持基线JPEG（不支持渐进式）
- 固定4:2:0色度子采样
- 使用标准霍夫曼表（不针对每张图片优化）
- 不支持EXIF元数据
详见 LICENSE 文件。
欢迎贡献！请先阅读 docs/CONTRIBUTING.md。
make cleanlibjpeg/
├── src/ # Source code / 源代码
│ ├── jpeg_encoder.h # Encoder header / 编码器头文件
│ ├── jpeg_encoder.c # Encoder implementation / 编码器实现
│ ├── jpeg_decoder.h # Decoder header / 解码器头文件
│ ├── jpeg_decoder.c # Decoder implementation / 解码器实现
│ ├── jpeg_simd.h # SIMD header / SIMD头文件
│ └── jpeg_simd.c # SIMD implementation / SIMD实现
├── examples/ # Example programs / 示例程序
│ ├── example.c # RGB encoding example / RGB编码示例
│ ├── example_yuv.c # YUV420 encoding example / YUV420编码示例
│ ├── example_uyvy.c # UYVY encoding example / UYVY编码示例
│ └── example_decode.c # JPEG decoding example / JPEG解码示例
├── docs/ # Documentation / 文档
│ ├── API.md # API documentation / API文档
│ └── CONTRIBUTING.md # Contributing guide / 贡献指南
├── build/ # Build output (generated) / 编译输出（自动生成）
├── Makefile # Build configuration / 编译配置
├── README.md # This file / 本文件
└── LICENSE # License file / 许可证文件