Metadata API

Sharp provides rich metadata manipulation capabilities for reading, modifying, and writing image metadata information.

Reading Metadata

Basic Usage

import sharp from 'sharp';

// Read image metadata
const metadata = await sharp('input.jpg').metadata();
console.log(metadata);

Metadata Object Structure

{
  format: 'jpeg',           // Image format
  width: 1920,              // Width
  height: 1080,             // Height
  space: 'srgb',            // Color space
  channels: 3,              // Number of channels
  depth: 'uchar',           // Bit depth
  density: 72,              // Resolution
  hasProfile: false,        // Has color profile
  hasAlpha: false,          // Has alpha channel
  isOpaque: true,           // Is opaque
  orientation: 1,           // EXIF orientation
  exif: { ... },            // EXIF data
  icc: { ... },             // ICC profile
  iptc: { ... },            // IPTC data
  xmp: { ... },             // XMP data
  tifftagPhotoshop: { ... } // Photoshop TIFF tag
}

EXIF Data

Reading EXIF

const metadata = await sharp('input.jpg').metadata();

if (metadata.exif) {
  console.log('EXIF Data:', metadata.exif);
  
  // Parse EXIF data
  const exif = sharp.exif(metadata.exif);
  console.log('Capture Time:', exif.DateTime);
  console.log('Camera Model:', exif.Model);
  console.log('ISO:', exif.ISOSpeedRatings);
}

Writing EXIF

// Create EXIF data
const exif = sharp.exif({
  IFD0: {
    ImageDescription: 'Image processed by Sharp',
    Copyright: '© 2024'
  },
  IFD1: {
    Orientation: 1
  },
  EXIF: {
    DateTimeOriginal: new Date().toISOString(),
    UserComment: 'Processed with Sharp'
  }
});

// Write EXIF data
await sharp('input.jpg')
  .withMetadata({ exif })
  .jpeg()
  .toFile('output.jpg');

ICC Color Profile

Reading ICC Profile

const metadata = await sharp('input.jpg').metadata();

if (metadata.icc) {
  console.log('ICC Profile:', metadata.icc);
}

Embedding ICC Profile

// Embed sRGB ICC profile
await sharp('input.jpg')
  .withMetadata({ icc: 'srgb' })
  .jpeg()
  .toFile('output.jpg');

// Embed custom ICC profile
const iccProfile = fs.readFileSync('custom.icc');
await sharp('input.jpg')
  .withMetadata({ icc: iccProfile })
  .jpeg()
  .toFile('output.jpg');

IPTC Data

Reading IPTC

const metadata = await sharp('input.jpg').metadata();

if (metadata.iptc) {
  console.log('IPTC Data:', metadata.iptc);
}

Writing IPTC

const iptc = {
  '2:05': 'Object Name',
  '2:15': 'Category',
  '2:25': 'Keywords',
  '2:55': 'Date Created',
  '2:80': 'By-line',
  '2:116': 'Copyright'
};

await sharp('input.jpg')
  .withMetadata({ iptc })
  .jpeg()
  .toFile('output.jpg');

XMP Data

Reading XMP

const metadata = await sharp('input.jpg').metadata();

if (metadata.xmp) {
  console.log('XMP Data:', metadata.xmp);
}

Writing XMP

const xmp = `
<x:xmpmeta xmlns:x="adobe:ns:meta/">
  <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
    <rdf:Description rdf:about=""
      xmlns:dc="http://purl.org/dc/elements/1.1/">
      <dc:title>Image processed by Sharp</dc:title>
      <dc:creator>Sharp</dc:creator>
    </rdf:Description>
  </rdf:RDF>
</x:xmpmeta>
`;

await sharp('input.jpg')
  .withMetadata({ xmp })
  .jpeg()
  .toFile('output.jpg');

Orientation Information

Reading Orientation

const metadata = await sharp('input.jpg').metadata();
console.log('Image Orientation:', metadata.orientation);

Auto Rotate

// Automatically rotate according to EXIF orientation
await sharp('input.jpg')
  .rotate()  // Auto rotate
  .jpeg()
  .toFile('output.jpg');

Resolution Information

Reading Resolution

const metadata = await sharp('input.jpg').metadata();
console.log('Resolution:', metadata.density);

Set Resolution

await sharp('input.jpg')
  .withMetadata({ density: 300 })
  .jpeg()
  .toFile('output.jpg');

Preserve Metadata

Preserve All Metadata

// Preserve all existing metadata
await sharp('input.jpg')
  .resize(800, 600)
  .withMetadata()
  .jpeg()
  .toFile('output.jpg');

Selective Preserve

// Preserve EXIF data only
await sharp('input.jpg')
  .resize(800, 600)
  .withMetadata({ exif: true })
  .jpeg()
  .toFile('output.jpg');

// Preserve EXIF and ICC
await sharp('input.jpg')
  .resize(800, 600)
  .withMetadata({ exif: true, icc: true })
  .jpeg()
  .toFile('output.jpg');

Remove Metadata

Remove All Metadata

// Remove all metadata
await sharp('input.jpg')
  .resize(800, 600)
  .jpeg()
  .toFile('output.jpg');

Remove Specific Metadata

// Remove EXIF but keep others
await sharp('input.jpg')
  .resize(800, 600)
  .withMetadata({ exif: false })
  .jpeg()
  .toFile('output.jpg');

Batch Metadata Processing

Batch Reading

const fs = require('fs').promises;

async function batchReadMetadata(directory) {
  const files = await fs.readdir(directory);
  const results = [];
  
  for (const file of files) {
    if (file.match(/\.(jpg|jpeg|png|webp)$/i)) {
      try {
        const metadata = await sharp(`${directory}/${file}`).metadata();
        results.push({ file, metadata });
      } catch (error) {
        console.error(`Failed to read metadata for ${file}:`, error.message);
      }
    }
  }
  
  return results;
}

Batch Writing

async function batchWriteMetadata(directory, metadata) {
  const files = await fs.readdir(directory);
  
  for (const file of files) {
    if (file.match(/\.(jpg|jpeg|png|webp)$/i)) {
      try {
        await sharp(`${directory}/${file}`)
          .withMetadata(metadata)
          .toFile(`${directory}/processed_${file}`);
      } catch (error) {
        console.error(`Failed to process ${file}:`, error.message);
      }
    }
  }
}

Metadata Validation

Validate Metadata Integrity

async function validateMetadata(filePath) {
  try {
    const metadata = await sharp(filePath).metadata();
    
    // Check basic properties
    if (!metadata.width || !metadata.height) {
      throw new Error('Missing dimensions.');
    }
    
    // Check format
    if (!metadata.format) {
      throw new Error('Missing format.');
    }
    
    // Check channel count
    if (!metadata.channels) {
      throw new Error('Missing channel info.');
    }
    
    return {
      valid: true,
      metadata
    };
  } catch (error) {
    return {
      valid: false,
      error: error.message
    };
  }
}

Performance Optimization

Read Only Required Metadata

// Only read basic info, do not parse EXIF
const metadata = await sharp('input.jpg')
  .metadata({ pages: -1 });

// Read EXIF only
const metadata = await sharp('input.jpg')
  .metadata({ exif: true });

Streaming Processing

const fs = require('fs');

// Read metadata by stream
const stream = fs.createReadStream('input.jpg');
const metadata = await sharp(stream).metadata();

Error Handling

try {
  const metadata = await sharp('input.jpg').metadata();
  console.log('Metadata:', metadata);
} catch (error) {
  if (error.code === 'VipsForeignLoad') {
    console.error('Unsupported image format');
  } else if (error.code === 'VipsForeignLoadLimit') {
    console.error('Image is too large');
  } else {
    console.error('Failed to read metadata:', error.message);
  }
}

Related Links

• Sharp Constructor
• Image Processing API
• Output Formats API
• Utilities API