According to a recent study, people remember only 10% of the content they hear but 65% of the images they see. Images are a key feature of any modern website as visuals increase the visitor’s desire to read the content by 80%. On the one hand, we need high-quality images to attract visitors to our website. On the other hand, high-quality images tend to be large and slow-loading, which discourages visitors. This, in turn, affects page rank. 

Organizations are implementing image optimization techniques to make their websites more attractive, load faster and rank higher. This article provides an overview of image optimization.

What Is Website Image Optimization?

Image optimization is the process of delivering high-quality images for the web while keeping the smallest file size. Large images slow down website loading times; optimizing images reduces the loading time of web pages. 

One of the biggest issues of website management is keeping the page loading time to a minimum. Slow pages increase visitors’ bounce rates. According to Google, if a webpage load takes more than 3 seconds, bounce rates increase 32%. This is one of the reasons Google is penalizing slow sites with low page rankings. 

Image Optimization Methods

There are several methods to optimize your images. The three most commonly used are: caching, resizing, and compressing, as explained below. 


You can use this method to store the image files inside the browser’s cache or on a proxy server. Caching enables a shorter path to the images by reducing application requests. Fewer application requests mean reduced loading times. 


This involves reducing the dimensions of the image in pixels. Resizing changes the amount of data involved, sometimes degrading the image. One resizing technique is called resampling. When you resample, you reduce the amount of data involved by reducing the pixels in the image. You can also resize without resampling. In this case, you only change one variable: the physical dimensions (length and height) of the image. Or you can change the resolution. The larger the image, the lower its resolution.


Bitmap images consist of pixels that can be compressed to reduce the file size. Compressing an image consists of removing the redundant data, for example, similar pixels in the image’s background. This method eliminates the slight differences in the pixels’ colors, making it uniform. While it reduces the file size, the compression almost always degrades the image quality.

Compression can be lossy or lossless. Lossy compression eliminates the extra data permanently. Lossless compression enables the user to recover the data by restoring the image back to its original size. 

Tips to Optimize Your Images for Web

Optimizing your website images contributes to giving your visitors a better user experience. Below, you’ll find the ten best practices for image optimization.

1. Choose the right format

Combining different image formats on your website allows you to play with their sizes. For instance, PNG images are larger but work well for logos since they tend to have a transparent background. JPG is the most used format for photographs, as it supports a large color range and detailed images. Vector images are very popular for icons and logos since they are the smallest and work with a limited color range. 

2. Resize the image

You can do this with an image editor, defining the dimensions of the image in pixels. A smaller image will reduce the image file size.

You can also use an image optimization plugin. These generally work by compressing images by reducing the number of pixels. This reduces the image size without a significant impact on image quality.

TIP: If you’re wondering what size your images should be, take a look at this guide to WordPress image sizes.

3. Use a content delivery network

A content delivery network (CDN) is a network of servers distributed geographically to ensure fast delivery of Internet content. A CDN fetches the images from the closest server to the user. The CDN uses cache controls and automated file compression to optimize the loading speed.

4. Progressive loading

Exporting the images in progressive mode enables the website to present the image in a series of layers. The image is first rendered in a pixelated version, which is later replaced by a number of layers, each one better quality than the previous one. You can use JavaScript to code your own tool. However, image optimization tools and digital asset management solutions often have the option of selecting progressive loading.

5. Implementing a digital asset management solution

Digital asset management (DAM) software can automate file formatting, compressing the images to the size and quality required by the target website.

6. Use lazy loading

Lazy loading means loading the images after the above-the-fold content is loaded. This means for example, that images at the bottom of the page are not loaded if the user does not scroll down. You can configure lazy loading by using your own JavaScript code or you can browse the web: there are several techniques you can experiment with, such as Intersection Observer API. There are also tools that can do the lazy loading for you, such as Yall.js. This feature is present in image optimization solutions and some DAMs.

7. Optimizing the thumbnails

Thumbnails are a standard feature of e-commerce, hobby and catalog sites. Thumbnails can be deceptive with their apparent small size. You may think they don’t take much space. But when you add up hundreds of thumbnails, they can slow your loading speed. Controlling the size of thumbnails is a good practice to keep the overall webpage weight on track. You can do this by using a light image format and adjusting the dimensions.

8. Use image enhancement techniques

This refers to the process of adjusting images so the resulting image is more suitable for display. Using an image editor or an image optimization tool, you can modify the background, brightness or make the image sharper. Photoshop is the most common tool for enhancing or modifying images but you can also use online editors such as

9. Use “alt text” to help users access your images

Alternative text describes an image’s content and features. This helps accessibility readers to “read” the image for visually impaired users, improving their user experience. In most content management systems (CMS) such as Hubspot or WordPress, you can simply click on an image in a blog post to see a rich text module. This text module is the place you can create the image’s alt text. The alt text you create is written into the webpage’s HTML source code. You should be descriptive and specific, keeping the alt text less than 125 characters. 

10. Name your images naturally

An image caption is a text that appears below an image, usually giving it a label or providing an explanation. A logical and concise caption can help when searching the image in a repository. An added benefit of good captioning practices is helping your users to search for your images. 

Wrap Up

In the competitive digital world, every improvement made to your website matters. Image optimization is a powerful tool that can positively affect your page loading speed. This will encourage your visitors to stay longer on your website, improving their user experience.

Since visitor’s expectations are only going to increase over time, delivering an attractive and fast-loading website can help you position your website in a better ranking. The techniques and practices mentioned in this article should get you started. 

About the Author

Gilad David Maayan is a technology writer who has worked with over 150 technology companies including SAP, Samsung NEXT, NetApp and Imperva, producing technical and thought leadership content that elucidates technical solutions for developers and IT leadership.


Comments are closed.