Next.js Image vs. HTML <img>: Optimizing Website Images for Performance

Images are an integral part of web design, but they can significantly impact website performance if not optimized properly. In this article, we will explore the benefits of using Next.js Image compared to the standard HTML <img> element and provide examples of how you can implement similar optimizations using HTML.

Size Optimization:

Next.js Image:

Next.js Image excels in size optimization by automatically serving correctly sized images for each device. It utilizes modern image formats like WebP and AVIF to reduce file sizes while maintaining quality. The component determines the width and height of the image based on the imported file, preventing layout shifts during image loading.

Example:

import Image from 'next/image';
import profilePic from '../public/profile.jpg';

const MyComponent = () => (
  <Image
    src={profilePic}
    alt="Profile Picture"
    // Width and height are automatically provided based on the imported image file
  />
);

HTML <img>:

To optimize image sizes using HTML, you can resize and compress images before uploading them to your website. Additionally, specify the width and height attributes in the tag to reserve space for the image, ensuring proper layout and preventing layout shifts.

Example:

<img src="image.jpg" alt="Description of the image" width="500" height="300" />

Visual Stability

Next.js Image:

Next.js Image addresses visual stability concerns by automatically preventing layout shifts during image loading. It reserves space for the image and applies techniques like blur-up placeholders and native browser lazy loading.

Example:

import Image from 'next/image';
import profilePic from '../public/profile.jpg';

const MyComponent = () => (
  <Image
    src={profilePic}
    alt="Profile Picture"
    // Width and height are automatically provided based on the imported image file
    // Additional props for visual stability can be added
    // e.g., placeholder="blur" for blur-up placeholders
  />
);

HTML <img>:

To maintain visual stability, reserve space for the image using CSS. Set the width and height of the parent container and use CSS properties like object-fit to control how the image is displayed within its container.

Example:

<div style="width: 500px; height: 300px;">
  <img src="image.jpg" alt="Description of the image" style="object-fit: cover; width: 100%; height: 100%;" />
</div>

Lazy Loading

Next.js Image:

Next.js Image leverages native browser lazy loading, ensuring that images are loaded only when they enter the viewport. This improves page load times, particularly for websites with numerous images.
Example:

import Image from 'next/image';
import profilePic from '../public/profile.jpg';

const MyComponent = () => (
  <Image
    src={profilePic}
    alt="Profile Picture"
    // Width and height are automatically provided based on the imported image file
    // Lazy loading is enabled by default
  />
);

HTML <img>:

To implement lazy loading using HTML, use the loading="lazy" attribute in the tag. This attribute instructs the browser to lazily load the image when it enters the viewport.

Example:

<img src="image.jpg" alt="Description of the image" loading="lazy" />

Image Optimization

Next.js Image:

Next.js Image provides automatic image optimization, including size reduction through modern image formats and on-demand image resizing for images stored on remote servers. It also integrates with content delivery networks (CDNs) for optimized image delivery.

Example:

import Image from 'next/image';
import profilePic from '../public/profile.jpg';

const MyComponent = () => (
  <Image
    src={profilePic}
    alt="Profile Picture"
    // Width and height are automatically provided based on the imported image file
    // Image optimization is handled by Next.js
  />
);

HTML <img>:

To optimize images using HTML, consider compressing images before uploading them to your website. Use image compression tools or services to reduce file sizes while maintaining acceptable image quality. Additionally, leverage CDNs to serve optimized versions of your images, benefiting from caching, compression, and content delivery.

Conclusion

While the standard HTML <img> element offers some image optimization possibilities, Next.js Image provides a more comprehensive and streamlined solution for optimizing images within the Next.js framework. Next.js Image offers size optimization, visual stability, lazy loading, and automatic image optimization features, allowing developers to deliver high-performance websites with ease.

However, if you're working with HTML, you can still achieve image optimization by resizing and compressing images, specifying width and height attributes, implementing lazy loading, and utilizing CDNs for optimized image delivery. Consider your specific requirements and the level of optimization needed when deciding between Next.js Image and HTML <img>.