How to Optimize Images in Next.js - Speed Up Your Website

Image optimization is a crucial part of web development for improving website performance, user experience, and SEO rankings. Large and unoptimized images can slow down your site, increasing bounce rates and reducing conversions. Luckily, Next.js comes with built-in image optimization features that make this process seamless.

In this article, we’ll explore how to optimize images in Next.js using its built-in <Image> component, also understand the benefits of this optimization, and provide some practical tips for further enhancing image performance in your Next.js projects.

Image Optimization in Next.js

Next.js has an Image Optimization API that automatically optimizes images on-demand for faster loading. This optimization process includes lazy loading, responsive images, and automatic format conversion to modern formats like WebP.

The key component to achieve image optimization in Next.js is the <Image> component provided by next/image. This component offers a lot of functionality out of the box to ensure your images are displayed in the best possible way.

Step 1: Import the <Image> Component

import Image from "next/image";

Step 2: Add Domains for External Images

If you’re fetching images from external domains, make sure to specify those domains in your next.config.js file.

/** @type {import('next').NextConfig} */
const nextConfig = {
  images: {
    remotePatterns: [
      {
        protocol: "https",
        hostname: "cdn.geekboots.com",
      },
    ],
  },
};

export default nextConfig;

Step 3: Use the <Image> Component

<Image
    src={`/gallery/img1.jpg`}
    alt={loc.location}
    width={300}
    height={250}
    className="w-full h-64 object-cover"
/>

How the <Image> Component Works

• src: The path to the image you want to optimize.

• alt: The alt text for accessibility and SEO.

• width and height: You must define the dimensions of the image (in pixels) for layout purposes.

• The component ensures that the image is optimized by resizing it based on the viewport, converting it to modern formats like WebP, and lazy loading it by default.

Additional Options

You can further customize the behavior of the <Image> component with several other props.

1. layout

You need to specify how the image should behave on the page. It can take the following values

• intrinsic: This option automatically resizes the image based on the screen size while maintaining its aspect ratio.

• responsive: Automatically resizes the image based on the screen size while maintaining the aspect ratio.

• fixed: A fixed size regardless of screen size.

• fill: Perfect for backgrounds or when you want the image to stretch to fill its parent container.

<Image
    src={`/gallery/img1.jpg`}
    alt={loc.location}
    width={300}
    height={250}

    layout="intrinsic"
/>

2. quality

You can specify the quality of the image (between 1 and 100), with 75 being the default.

<Image
    src={`/gallery/img1.jpg`}
    alt={loc.location}
    width={300}
    height={250}

    quality={90}
/>

3. priority

For images that are important to the page load (like a hero image), you can use the priority prop to preload the image.

<Image
    src={`/gallery/img1.jpg`}
    alt={loc.location}
    width={300}
    height={250}

    priority={true}
/>

4. loading

You can also use loading prop by passing lazy, it will only load when the user scrolls to them, improving page load times.

<Image
    src={`/gallery/img1.jpg`}
    alt={loc.location}
    width={300}
    height={250}

    loading="lazy"
/>

5. placeholder

To display a placeholder while the image is loading, you can use placeholder="blur" to add a blurry effect.

<Image
    src={`/gallery/img1.jpg`}
    alt={loc.location}
    width={300}
    height={250}

    placeholder="blur"
    blurDataURL="/gallery/img1.jpg"  // A low-resolution version of the image
/>

Why Optimize Images?

Optimizing images can significantly improve the loading time of your website, which is essential for:

• Better Performance: Faster loading times, especially on slower networks, increase user engagement.

• Improved SEO: Page speed is a key factor in Google's ranking algorithm. Optimized images can give your site an SEO boost.

• Enhanced User Experience: With faster page loads, users will have a smoother and more enjoyable experience.

• Reduced Bandwidth Usage: Image optimization reduces file sizes, which minimizes the amount of data transferred and saves bandwidth.

Tips for Further Optimizing Images

While Next.js handles a lot of image optimization out of the box, here are some additional tips to ensure maximum performance:

• Use Modern Formats: Always use modern image formats like WebP whenever possible. WebP provides significantly better compression than JPEG and PNG, reducing file sizes by 25-34%. Fortunately, Next.js automatically serves WebP versions of images where supported.

• Properly Size Your Images: Upload images that are properly sized for your website. Avoid using images larger than needed for the largest display size. The <Image> component helps by automatically resizing images, but it's still a good practice to avoid uploading excessively large files.

• Optimize Image Dimensions: Ensure that you specify the correct width and height attributes for each image. This allows the browser to allocate space for the image before it's loaded, which helps prevent layout shifts (a key factor in Core Web Vitals).

• Use CDNs for Faster Delivery: Consider using a Content Delivery Network (CDN) to host your images, so they load faster for users across different geographical locations.

Conclusion

Next.js makes image optimization effortless with its built-in <Image> component. It provides better performance, responsive images, lazy loading, and conversion to modern formats like WebP. By using Next.js’s Image Optimization API, you can enhance the performance of your website, improve SEO rankings, and provide a superior user experience.

With the steps and tips outlined in this article, you should now have a good understanding of how to optimize images effectively in Next.js. Implementing these strategies will ensure your site is fast, efficient, and well-optimized for users across various devices and networks.