如何知道从流中获取的图像格式？

from PIL import Image
import io

def get_image_format(image_stream):
    try:
        img = Image.open(io.BytesIO(image_stream))
        return img.format
    except IOError:
        return None

# 示例
image_stream = b'\xFF\xD8\xFF...'  # 假设这是JPEG图像流
format = get_image_format(image_stream)
print(f"Image format: {format}")

const sharp = require('sharp');

async function getImageFormat(imageStream) {
    try {
        const metadata = await sharp(imageStream).metadata();
        return metadata.format;
    } catch (error) {
        return null;
    }
}

// 示例
const imageStream = Buffer.from('\xFF\xD8\xFF...', 'binary');  // 假设这是JPEG图像流
getImageFormat(imageStream).then(format => {
    console.log(`Image format: ${format}`);
});

const http = require('http');

http.get('http://example.com/image.jpg', (res) => {
    console.log(`Image format: ${res.headers['content-type']}`);
});