configuring-image-optimization

name	configuring-image-optimization
description	Teach image optimization configuration changes in Next.js 16. Use when configuring images, troubleshooting image loading, or migrating image settings. Use when this capability is needed.
metadata	{"author":"djankies"}

Image Optimization Configuration in Next.js 16

Breaking Changes

1. Removed Configuration Options

domains (removed)

• Replaced by remotePatterns
• More secure with pattern matching instead of wildcard domain access

loader (removed for 'default')

• Custom loaders must now be specified explicitly
• No implicit fallback to default loader behavior

formats array changes

• AVIF format now enabled by default
• Order affects format preference during negotiation

2. Changed Default Values

minimumCacheTTL

• Old default: 60 seconds
• New default: 31536000 seconds (1 year)
• Requires manual override for shorter cache durations

deviceSizes

• Updated default breakpoints to match modern devices
• Old: [640, 750, 828, 1080, 1200, 1920, 2048, 3840]
• New: [640, 750, 828, 1080, 1200, 1920, 2048, 3840, 4096]

imageSizes

• Updated for modern layout shifts
• Old: [16, 32, 48, 64, 96, 128, 256, 384]
• New: [16, 32, 48, 64, 96, 128, 256, 384, 512]

3. Security Enhancements

dangerouslyAllowSVG

• Now requires explicit contentDispositionType setting
• Default changed to 'attachment' for security
• Inline SVG rendering requires opt-in configuration

unoptimized

• Stricter enforcement in production
• Warning logs for unoptimized images in development
• Performance metrics now track optimization bypass

Core Configuration

Basic Setup

module.exports = {
  images: {
    remotePatterns: [
      {
        protocol: 'https',
        hostname: 'example.com',
        port: '',
        pathname: '/images/**',
      },
    ],
    deviceSizes: [640, 750, 828, 1080, 1200, 1920, 2048, 3840],
    imageSizes: [16, 32, 48, 64, 96, 128, 256, 384],
    formats: ['image/webp', 'image/avif'],
    minimumCacheTTL: 31536000,
  },
}

remotePatterns

Securely allow external image sources:

module.exports = {
  images: {
    remotePatterns: [
      {
        protocol: 'https',
        hostname: 'cdn.example.com',
        pathname: '/media/**',
      },
      {
        protocol: 'https',
        hostname: '*.cloudinary.com',
        pathname: '/**',
      },
    ],
  },
}

Pattern properties:

• protocol: 'http' or 'https'
• hostname: exact match or wildcard (*.example.com)
• port: specific port number (optional)
• pathname: glob patterns using ** for nested paths

minimumCacheTTL

Controls optimized image cache duration:

module.exports = {
  images: {
    minimumCacheTTL: 60,
  },
}

Common values:

• 60: Frequently changing images
• 3600: Hourly updates (1 hour)
• 86400: Daily updates (1 day)
• 31536000: Static assets (1 year, default)

imageSizes

Sizes for images with explicit sizes prop:

module.exports = {
  images: {
    imageSizes: [16, 32, 48, 64, 96, 128, 256, 384],
  },
}

Usage:

<Image
  src="/avatar.jpg"
  sizes="(max-width: 768px) 64px, 128px"
  width={128}
  height={128}
  alt="Avatar"
/>

deviceSizes

Viewport breakpoints for responsive images:

module.exports = {
  images: {
    deviceSizes: [640, 750, 828, 1080, 1200, 1920, 2048, 3840],
  },
}

Usage:

<Image
  src="/hero.jpg"
  fill
  sizes="100vw"
  alt="Hero"
/>

localPatterns

Control local file optimization access:

module.exports = {
  images: {
    localPatterns: [
      {
        pathname: '/public/uploads/**',
        search: '',
      },
    ],
  },
}

Migration Patterns

From domains to remotePatterns

Before:

module.exports = {
  images: {
    domains: ['example.com', 'cdn.example.com'],
  },
}

After:

module.exports = {
  images: {
    remotePatterns: [
      {
        protocol: 'https',
        hostname: 'example.com',
        pathname: '/**',
      },
      {
        protocol: 'https',
        hostname: 'cdn.example.com',
        pathname: '/**',
      },
    ],
  },
}

Adjusting Cache for Dynamic Content

Before (60s default):

module.exports = {
  images: {
    domains: ['api.example.com'],
  },
}

After (explicit cache):

module.exports = {
  images: {
    remotePatterns: [
      {
        protocol: 'https',
        hostname: 'api.example.com',
        pathname: '/dynamic-images/**',
      },
    ],
    minimumCacheTTL: 300,
  },
}

Restricting Image Sources

Before:

module.exports = {
  images: {
    domains: ['*.cloudinary.com'],
  },
}

After:

module.exports = {
  images: {
    remotePatterns: [
      {
        protocol: 'https',
        hostname: 'res.cloudinary.com',
        pathname: '/my-account/image/upload/**',
      },
    ],
  },
}

Common Configurations

Production

module.exports = {
  images: {
    remotePatterns: [
      {
        protocol: 'https',
        hostname: 'cdn.production.com',
        pathname: '/**',
      },
    ],
    formats: ['image/avif', 'image/webp'],
    minimumCacheTTL: 31536000,
    dangerouslyAllowSVG: false,
  },
}

Development

module.exports = {
  images: {
    remotePatterns: [
      {
        protocol: 'http',
        hostname: 'localhost',
        port: '3001',
        pathname: '/**',
      },
    ],
    minimumCacheTTL: 60,
  },
}

Multi-Environment

const isProd = process.env.NODE_ENV === 'production'

module.exports = {
  images: {
    remotePatterns: isProd
      ? [
          {
            protocol: 'https',
            hostname: 'cdn.production.com',
            pathname: '/**',
          },
        ]
      : [
          {
            protocol: 'http',
            hostname: 'localhost',
            port: '3001',
            pathname: '/**',
          },
        ],
    minimumCacheTTL: isProd ? 31536000 : 60,
  },
}

Mobile-Optimized

module.exports = {
  images: {
    deviceSizes: [375, 414, 640, 750, 828, 1080],
    imageSizes: [24, 32, 48, 64, 96],
  },
}

SVG Support

module.exports = {
  images: {
    dangerouslyAllowSVG: true,
    contentDispositionType: 'inline',
    contentSecurityPolicy: "default-src 'self'; script-src 'none'; sandbox;",
  },
}

Quick Troubleshooting

Image Not Loading

Check pattern matches URL:

remotePatterns: [
  {
    protocol: 'https',
    hostname: 'example.com',
    pathname: '/images/**',
  },
]

Verify:

• Protocol matches (https vs http)
• Hostname exact or wildcard match
• Pathname pattern includes image path

Cache Not Updating

Override default TTL:

module.exports = {
  images: {
    minimumCacheTTL: 3600,
  },
}

Clear build cache:

rm -rf .next
npm run build

SVG Not Rendering

Enable with security:

module.exports = {
  images: {
    dangerouslyAllowSVG: true,
    contentDispositionType: 'inline',
    contentSecurityPolicy: "default-src 'self'; script-src 'none'; sandbox;",
  },
}

Performance Issues

Reduce size variants:

module.exports = {
  images: {
    deviceSizes: [640, 828, 1200, 1920],
    imageSizes: [32, 64, 128, 256],
  },
}

Detailed References

For comprehensive examples and advanced configurations, see the references/ directory:

configuration-examples.md

• Complete configuration patterns
• E-commerce, CMS, social media setups
• Multi-CDN configurations
• Industry-specific examples

security-settings.md

• SVG security best practices
• Content Security Policy options
• Content Disposition configurations
• Security monitoring strategies

troubleshooting.md

• Advanced debugging techniques
• Edge cases and solutions
• Performance optimization
• Runtime error resolution

migration-guide.md

• Step-by-step migration from Next.js 15
• Complex migration scenarios
• Verification checklist
• Rollback strategies

Related Skills

• Use images-component skill for Next.js Image component usage
• Use images-responsive skill for responsive image patterns
• Use images-loaders skill for custom image loader configuration

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