JPG 智能压缩

复制import subprocess
import sys

# 调用 mozjpeg 的 cjpeg 压缩 JPEG（需安装 mozjpeg）
input_path = "input.jpg"
output_path = "output.jpg"
quality = 80  # 0-100，越低压缩率越高

try:
    # cjpeg 从 stdin 读原始图像，输出压缩 JPEG 到 stdout
    with open(input_path, "rb") as f_in:
        result = subprocess.run(
            ["cjpeg", "-quality", str(quality), "-outfile", output_path],
            stdin=f_in,
            capture_output=True,
            check=True
        )
    print(f"压缩完成: {output_path}")
except FileNotFoundError:
    print("错误: 未安装 mozjpeg，请先安装 (brew install mozjpeg)", file=sys.stderr)
except subprocess.CalledProcessError as e:
    print(f"压缩失败: {e.stderr.decode()}", file=sys.stderr)

复制package main

import (
	"fmt"
	"image/jpeg"
	"os"
)

func main() {
	// 使用 Go 标准库 JPEG 编码器模拟 mozjpeg 压缩（仅演示 API 调用方式）
	inputPath := "input.jpg"
	outputPath := "output.jpg"
	quality := 80 // 1-100

	fileIn, err := os.Open(inputPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "打开输入文件失败: %v\n", err)
		return
	}
	defer fileIn.Close()

	img, err := jpeg.Decode(fileIn)
	if err != nil {
		fmt.Fprintf(os.Stderr, "解码 JPEG 失败: %v\n", err)
		return
	}

	fileOut, err := os.Create(outputPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "创建输出文件失败: %v\n", err)
		return
	}
	defer fileOut.Close()

	// 设置压缩质量参数
	opt := &jpeg.Options{Quality: quality}
	if err := jpeg.Encode(fileOut, img, opt); err != nil {
		fmt.Fprintf(os.Stderr, "编码 JPEG 失败: %v\n", err)
		return
	}

	fmt.Println("压缩完成:", outputPath)
}

复制// 浏览器端使用 Canvas API 压缩 JPEG（类似 guetzli 的感知优化思路）
function compressJPEG(file, quality = 0.8) {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = (e) => {
      const img = new Image();
      img.onload = () => {
        const canvas = document.createElement('canvas');
        canvas.width = img.width;
        canvas.height = img.height;
        const ctx = canvas.getContext('2d');
        ctx.drawImage(img, 0, 0);
        // 以指定质量重新编码为 JPEG
        canvas.toBlob(
          (blob) => {
            if (blob) resolve(blob);
            else reject(new Error('编码失败'));
          },
          'image/jpeg',
          quality
        );
      };
      img.onerror = () => reject(new Error('图片加载失败'));
      img.src = e.target.result;
    };
    reader.onerror = () => reject(new Error('文件读取失败'));
    reader.readAsDataURL(file);
  });
}

// 使用示例（在浏览器控制台运行）
// const fileInput = document.querySelector('input[type="file"]');
// fileInput.addEventListener('change', async (e) => {
//   const compressed = await compressJPEG(e.target.files[0], 0.7);
//   const url = URL.createObjectURL(compressed);
//   console.log('压缩后图片 URL:', url);
// });