How Do You Optimize Images For AMP (Accelerated Mobile Pages)?

Story Based Question

You’re working on an online news site that’s implementing AMP (Accelerated Mobile Pages) to speed up mobile page loading times. The site features high-quality images for each article, such as news photos, infographics, and editorial images. You want to make sure that these images are properly optimized for AMP to ensure fast loading on mobile devices, while still maintaining their visual quality. How do you optimize these images for AMP?

Exact Answer

To optimize images for AMP, you should use the <amp-img> tag instead of the standard <img> tag, ensure that images are responsive with the layout attribute, specify image dimensions, and serve properly compressed images in formats like WebP. Additionally, use lazy loading to improve performance and reduce page load times.

Explanation

AMP is designed to improve mobile page performance, and optimizing images is a key part of this process. To achieve faster loading times while still delivering high-quality images, you need to follow several best practices tailored to AMP’s requirements. Here’s how to optimize images for AMP:

1. Using the <amp-img> Tag: Unlike standard HTML, AMP requires you to use the <amp-img> tag for images. This tag is specifically designed for AMP pages and ensures that images load efficiently. It works similarly to the regular <img> tag but includes additional AMP-specific functionality to optimize image loading.
2. Setting Image Dimensions: With AMP, you must always specify the width and height of each image. This helps the browser to reserve space for the image before it fully loads, preventing layout shifts and improving the overall user experience. Be sure to provide accurate dimensions based on the display size of the image.
3. Responsive Images with the layout Attribute: The layout attribute controls how an image behaves across different screen sizes. Common values are:
   • responsive: Automatically adjusts the image size based on the container width, making it responsive to different screen sizes.
   • intrinsic: The image scales based on its intrinsic aspect ratio.
   • fixed: The image has a fixed size and doesn’t change with the container width.
   For most cases, you’ll use the responsive layout, especially for mobile-friendly designs.
4. Serving Compressed and Optimized Images: To improve load times, compress your images before uploading them. You can use formats like WebP for better compression, reducing file size without sacrificing quality. WebP images are smaller and faster to load compared to traditional JPEG or PNG formats, which is crucial for AMP performance.
5. Lazy Loading: AMP automatically implements lazy loading for images, which means images only load when they come into the viewport (as the user scrolls). This reduces the initial load time and enhances performance by deferring the loading of images that are not immediately visible on the screen.

Example

Let’s say you’re working on a news article about a recent sports event, and you have an image of the winning team. To optimize this image for AMP, here’s how you would implement it:

1. HTML Code for AMP Image:
   
   <amp-img
   src=”sports-team.jpg”
   alt=”Winning sports team holding the trophy”
   width=”1200″
   height=”800″
   layout=”responsive”>
   </amp-img>
   
2. Explanation:
   • The <amp-img> tag is used instead of the regular <img> tag to ensure AMP compatibility.
   • The src attribute points to the image URL, while the alt attribute provides a text description for accessibility.
   • The width and height attributes specify the image dimensions to prevent layout shifts while the page is loading.
   • The layout="responsive" ensures that the image scales properly based on the screen size, making it mobile-friendly and responsive.
3. Optimized Image Delivery:
   • You ensure that the sports-team.jpg is properly compressed and saved in WebP format to improve loading times on mobile devices.
   • If necessary, you could create multiple versions of the image for different screen resolutions using srcset to further enhance performance.
4. Lazy Loading in Action: AMP automatically handles lazy loading for the image. As the user scrolls down the article, the image of the sports team will load only when it’s about to appear on the screen, reducing the initial load time.

By following these AMP-specific image optimization practices, the news site’s images will load quickly on mobile devices, leading to a better user experience and improved page speed.