How to Optimize Images for Organic Search [2025 Update]

Image SEO requires the mastery of three specialisms: 1) technical optimization, 2) on-page SEO fundamentals, and 3) advanced UX. With search engines now equipped with cutting-edge AI-led interfaces and functionalities, optimizing images for maximum organic visibility is now more important than ever. This guide covers all the tactics you need to know, from structured data and image compression to mobile-first design principles and sitemaps, allowing you to create images as SEO-friendly as possible.

Why Images Matter for SEO in 2025

As we speak, Google is exploring and delivering innovative solutions to upgrade its search engine and make it more user-friendly, digital, and immersive. User experience (UX) has become quintessential in modern search, with Google at the forefront of its evolution. This has, by extension, resulted in swathes of visual features and elements now regular staples of any search engine results page (SERP).

Images, videos, timestamps, maps, carousels, and now AI Overviews are inundated with features and quirks that, ostensibly, place the user at the heart of the experience. Images, in particular, carry immense weight for users as they are handed increasingly more personalized responses on SERPs. What this means is that images are now being looked at for what they really are: vital assets that help search engines understand, rank, and present your content to users, rather than being viewed as just extras to pad websites with.

When images are correctly optimized for modern search engines, they can appear prominently in Google Image search results, improve content relevance signals, and provide valuable context in AI Overviews that users are gradually using more and more every day.

Why are we telling you this? It’s because as far as user expectations are concerned, the stakes are high. Users now demand more from their search experience. They want super fast page load speeds, accessible content, and visually engaging results across their devices. If your images lack the essential optimization, they can be detrimental to your UX, your page speed and, ultimately, your search rankings.

For companies partnering with digital marketing agencies like TechWyse for comprehensive, bespoke SEO strategies, image optimization represents an often-overlooked and under-explored opportunity full of potential. Let’s explore some simple yet effective ways to optimize your images, from three particular angles:

Technical optimization
On-page
UX

1. Technical Image SEO

Choose the Right Image File Format

Nowadays, websites can accommodate a range of image formats, but there is etiquette when it comes to choosing ones that offer quality without compromising on site speed.

MPB has a great resource that clearly helps you to understand the different image formats and covers their best practices for use across the web.

Source: MPB

The main image file types that Google can index are:

WebP: Lossy WebP files are approximately 25-34% smaller than JPEGs, and lossless files are 26% smaller than PNGs. These are now supported by all major browsers, making it the safest and preferred choice for most web applications.
JPEG (or JPG): Compatible with nearly all devices and boasting a wide range of colors, JPEG files can be reduced in size easily. However, JPEGs are lossy, which means that some data is lost during compression.
PNG: These files are also universal across devices, and unlike JPEG files, PNG files are lossless, so no data is lost during compression. However, they are often larger than JPEGs, so they require more resources to distribute between web servers.
SVG: These files use vectors rather than pixels to create images. While these are excellent for logos, diagrams and animations, they aren’t always ideal for still photos as the files end up too large.

While there are numerous other file types to consider, WebP files as your primary format with JPEG backups of a respectable quality will be suitable for most websites. Utilize SVG files for logos, icons and illustrations that need to scale, and PNG files for images that require transparency, and your page load speed times should still be fast.

Resize and Compress Images With Precision

Image size refers to the height and width of the image in pixels, and file size refers to the storage space it occupies. Both can slow down the loading speed of pages, because on every HTTP request, the browser has to load the full image, even if it’s bigger than the maximum width of the site viewport. Consider using tools to adjust image dimensions to preset widths and heights.

But remember, resolution also plays a factor in page speed. High-resolution images can make pages load more slowly. The standard resolution for images is 72 PPI (pixels per inch), although this has been debated in recent years, so it’s worth keeping each image’s resolution at this or a similar level.

Image compression is a practice that reduces file and image size, making them more suitable for quick loading and effective storage. Larger images contribute to higher bandwidth usage, which can cause a strain on web hosting resources. However, you also want to preserve visual quality, so it’s about getting the optimal balance.

A general rule of thumb is to compress images to be 100 KB or less, but for larger images, this may not be possible without seriously lowering the quality. Consider using image optimization tools like, TinyJPG, to compress images, then download and upload them to your site where you want the premium images to be, to lower your overall hosting costs and bandwidth usage.

Use Responsive Images

Google crawls and indexes pages primarily based on the mobile version of the site, due to the huge increase in mobile searches over the past several years. As mobile screens are smaller than desktop ones, it’s important to use responsive image techniques that allow your images to adapt to the appropriate size for the device that users are using.

Several content management systems (CMSs) have built-in responsive designs and themes; however, depending on the technical setup of your site, you may need to configure them through srcset attributes.

See example below:

<img src="product-image-800w.webp"

srcset="product-image-400w.webp 400w,

product-image-800w.webp 800w,

product-image-1600w.webp 1600w"

sizes="(max-width: 768px) 100vw,

(max-width: 1200px) 50vw,

800px"

Look Closely at Core Web Vitals

Page speed is a huge search ranking factor, but more than anything, it can make the difference between users staying on your site and bouncing. Page speed itself is fundamentally measured by three key Core Web Vitals (CWV) metrics:

Largest Contentful Paint (LCP)
Cumulative Layout Shift (CLS)
Interaction to Next Paint (INP)

For sites to be considered ‘in the green’ with CWV, they must satisfy some criteria.

LCP measures how quickly the largest element renders (which can often be a hero image). CLS prevents layout shifts by specifying image dimensions in the site’s HTML. INP ensures images don’t interfere with user interactions (such as button clicks or menu items).

It’s recommended to get an experienced developer to explore ways to improve CWV on your site, but the tips outlined in this guide will help, particularly the next one, as it pertains to INP and LCP.

Add Lazy Loading Where Relevant

Lazy loading is a technique where images only load when they appear in the user’s visible screen. Essentially, images further down the page won’t load until the user scrolls down and they appear within the viewport. This significantly improves initial page load times, reduces the amount of data transferred over the network, and enables users to engage with your page more quickly.

WordPress sites include native lazy loading (version 5.5 onwards), which automatically adds the attribute “lazy” to images. However, it’s important to disable them for critical images above the fold.

Consider these other technical improvements:

Deploy a Content Delivery Network (CDN) solution to serve your site content via servers that are closer to their geographic location.
Consider caching your image files via browser caching solutions to improve load times for returning website visitors, as they will be stored in the user’s browser.

2. On-Page Image SEO

Write and Optimize Image Alt Text

Alt text helps Google and other search engines understand the contents and context of your images, as they can’t interpret them visually. They are also used by screen readers to help visually impaired users digest content, and similarly, if images can’t be rendered by browsers, then alt text will appear.

Effective alt text is descriptive, keyword-optimized (not stuffed) and contextual.

Alt text recommendations:

Describe the image's content and function
Include relevant keywords naturally
Keep descriptions concise (125 characters or less)
Avoid redundant phrases like "image of" or "picture showing"

A poor alt text example would be:

It may be correct, but it doesn’t describe the image very well.

Conversely, a stronger description would be:

This does a much better job of explaining the image contents in a user’s mind and describing the image to Google.

Update Image Filenames

Image file names also help search engines comprehend image relevance and content to satisfy user search queries. Therefore, instead of uploading them with their default names (such as “IMG_63289.webp”), consider using descriptive alternatives like “blue-nissan-skyline-2004.webp”).

Always use hyphens to separate words and, where applicable, use keywords to make it easier for search engines to understand.

Add Schema (Structured Data) Markup

Schema refers to a structured data format that provides search engines with additional information about your site, and in this case, its images.

It helps them understand your images’ context and contents, which can improve visibility and indexing. For example, ImageObject schema markup can enhance your chances of generating rich results, including image thumbnails, titles, authors, publication dates, descriptions, ratings, license information, and more. When users see these eye-catching elements in SERPs, they could be more tempted to click through.

Additionally, Product schema might allow you to display an e-commerce product image, for example, with a price tag badge and stock levels in the Image Pack on SERPs or in Shopping results.

Adding schema is easily done by using structured data code on Schema.org, where you can input your specific image details (URLs, dimensions, descriptions, and so on), before integrating the code into the <head> of your HTML file.

Add an Image Sitemap

XML sitemaps help search engines discover your pages for indexing while helping them understand the site architecture and structure. They’re almost like a roadmap. Image sitemaps are similar, but provide Google with a list of all images on your site.

When creating an XML sitemap that includes image URLs or an image sitemap, it’s prudent to include image tags.

Here is an example of an image sitemap:

<url>

<loc>https://example.com/products/nike-shoes/</loc>

<image:image>

<image:loc>https://example.com/images/nike-showroom.webp</image:loc>

<image:title>Nike Showroom in London</image:title>

<image:caption>Nike trainers and casual shoes on display at showroom in London E17</image:caption>

</image:image>

</url>

Upload the file to the root folder of your domain (the main directory where your site’s files and folders are stored on the server, which depends on your web hosting environment). Once it’s uploaded, submit it through Google Search Console to ensure complete crawlability.

3. Image SEO and UX

Be Consistent Across Platforms

Most people will remember imagery before any words or titles, so it’s important to maintain a consistent brand identity across your website, social media profiles, and other channels. Ensure that the following are correct across all imagery and supporting materials:

Brand logo
Colour gradients
Logo placement and sizing
Photography composition and style
Typography and text overlays

This consistency will reinforce trust signals and user engagement at every touchpoint.

Remember, Mobile First!

As previously mentioned, with mobile traffic dominating search behaviour, mobile-first image optimization is essential. Consider portrait-oriented images for mobile viewing (reserve landscape ones for responsive hero images, for example), ensure text overlays and CTAs remain legible on smaller screens, and consider image galleries where users can take a closer look if need be.

Accessibility and DEI

Accessibility isn’t a check-box exercise, nor should it be. It’s about cultivating an inclusive design that benefits all users. Be mindful of the inclusion of alt text, colour contrasts between background imagery and text (or site page background and images in the foreground), and the visual capabilities and assistive technologies used by users.

Prioritize Original, Visual Content to Foster Trust

High-quality, original images serve as powerful trust signals that can improve user engagement and reduce bounce rates. While stock photos have their place, they do become repetitive to users if they see them everywhere. Remember, it’s always about topic relevance and alignment with your images.

Remember these golden rules:

Use original photography that serves a purpose
Showcase real team members, facilities, offices or infrastructure
Ensure all images align with your brand's professional standards
Create infographics that contain useful, topical information (other sites may want to link to it when they create content in this space, which could improve your backlink profile)

Common Image SEO Mistakes

Source: Deposit photos

Failing to specify image dimensions
Images causing layout shifts on websites, affecting clicks and engagement
Over-compressing images so they look heavily degraded or pixelated
Adding lazy loading to vital hero images or those above the fold
Using the wrong image format (e.g. GIF files for static images)
Uninspired or missing alt text
Keyword stuffing in filenames, captions or descriptions
Inconsistent image naming conventions
Not updating image sitemaps
Images that don’t provide valuable context to the page content
Inconsistent branding and visual elements
Poor mobile image optimization

Addressing Future Image SEO Trends

As AI continues to find its way in modern search, visual content will continue to play a vital role in SEO strategies. Marketers should quickly and proactively consider new ways to deliver compelling visual content.

Focus on contextually relevant and high-quality images, ensure that they support and add value to your written text, and consider how AI might interpret and use your visual content. You never know, one searcher may be delivered an incredibly personalized response that incorporates and references your visual asset(s) and they may become a customer before you know it.

Follow the tips outlined in this guide to give you the best possible chance of earning high rankings and traffic from your images.

Summary and Action Checklist

Finally, here’s your key summary and action points:

Use WebP and JPG images primarily, and PNG and SVG where relevant
Add responsive images either through your CMS or with srcset attributes
Compress images wisely to ensure a balance of good quality and respectable file size
Add lazy loading (if not already implemented)
Pay close attention to Core Web Vitals metrics
Write descriptive, keyword-optimized filenames and alt text
Implement the most appropriate schema markup for your pages and images
Generate and submit an up-to-date image sitemap to Google Search Console
Add captions where beneficial
Maintain brand consistency across your digital platforms
Optimize images and pages for mobile before desktop
Use images as trust and engagement signals
Prepare for an increasingly AI-led future for organic image search

Image optimization is a constantly evolving discipline, much like traditional SEO. Search engine algorithms, technology and user preferences will continue to change. However, these tips give you a baseline idea of how to position your website for image SEO success in 2025 and beyond.

Want to review your website's images and confirm their search potential? TechWyse's SEO experts can audit your current site and develop a bespoke strategy tailored to your business goals. Call 866-208-3095 or contact us here.