7 Guidelines for Image SEO in 2019

This Knowledge Center Article summarizes 7 ways to improve your SEO through image optimization.

General Best Practices

Optimizing visual content for SEO isn’t much different from optimizing textual content. Search engines are looking for the same fundamental attributes—good, high-quality content that’s made for users, not for search engines. Here are 7 quick tips to optimize images for SEO:

1. Balance image size and image quality
2. Use original, relevant images
3. Name your image accordingly
4. Add a caption
5. Write descriptive alternative text
6. Create an image sitemap
7. Add structured data

1. Balance Image Size & Image Quality

Images that are too large can slow down a site’s overall speed, especially on mobile. However, reducing the size of an image can also compromise image quality and user experience. Before resizing your images, consider the following:

• Find out what the largest image size displayed to the user is (i.e. don’t upload an image that’s larger than the width of your web page or the column it’s displayed in). Also consider how large you want the photo to be on your page.
• Determine what format your photo should be in. Google Images supports the following formats: BMP, GIF, JPEG, PNG, WebP, and SVG.

If you’re scaling your images in Adobe Photoshop, you can use the “Save for the Web” option to automatically minimize image size, while optimizing image quality. Also consider if lazy loading images that appear below the fold are conducive to how user’s interact with your site. Google has a great article on how lazy loading images conserves data and system resources, and ultimately boosts the page load speed.

2. Use Original, Relevant Images

If you have adequate resources, avoid using stock photos. Images, whether in the form of logos, photographs, or infographics, are more likely to capture users’ attention before your written content does.

Take the time to create or curate an appealing image that users haven’t seen a thousand times before and that’s also relevant to the page topic—don’t use an image for the sake of having an image.

Place images near relevant text, with the most important image placed at the top of the page, when possible. If you do opt for a stock photo, make sure there are no copyright conflicts associated with its use.

3. Name Your Image Accordingly

Before uploading your image onto your blog, website, or CMS, make sure that the name of the image file reflects what’s actually in the image. This helps Google understand what your image is when it’s crawling your source code.

Make sure to use hyphens (-) instead of underscores (_) to separate words.

Image file names also become part of your URL structure. Google uses both the image file name and its URL path to understand images. When a user opens the image in a tab or hovers their cursor over the image, they should see a relevant file name not something generic like “DSC1234.jpg” or “image2”.

4. Add a Caption

Don’t force a caption if an image can standalone but do consider if adding a caption will help provide context to the user. Adding captions improves user experience and captures 16% more readership than text as users are more likely to scan headings, images, and captions when they skim a web page.

5. Write Descriptive Alternative (Alt) Text

Websites are often guilty of keyword stuffing their alt text, which does nothing to help users or crawlers understand images.

Alt text comes into play for users who are visually impaired, have disabled image loading to increase speed, or have low-bandwidth Internet, and when an image won’t load. As such, alt text should read how you would describe the image to another person.

For example, a photo of the sunset over Mount Rainier should read something like “Sunset over Mount Rainier” not like a keyword-stuffed sentence such as “Mountains Seattle, Outdoors, Hiking, Trails, Landscape Photography”.

Although there is no character limit for alt text, try to keep it under ten words.

6. Create an Image Sitemap

Implementing an image sitemap houses all your images in one place and increases your page’s crawlability. Your image sitemap will help Google’s crawlers find images on your pages or server that haven’t been discovered yet.

Avoid hosting your images on third-party platforms. If any of those platforms are down or experiencing heavy traffic, the images on your page may fail to load.

7. Add Structured Data

Although Google has explicitly stated that structured data does not help you rank better, your image must have an image attribute for it to be crawlable and indexable.

Why Optimizing Images for SEO Matters

The most immediate impact of optimizing images for SEO comes from increased site speed, user experience, and accessibility. Easy opportunities like adjusting image size and adding alt text can make a world of difference for users. At a more quantitative level, Moz reports that 12.5% of all SERPs feature an image pack while Omnicore found that blogs with images received about 94% more views than blog posts without images.

What we really need to highlight here is what happened after the Google Images update in early 2019. In February, Google replaced the “View Image” button from its Google Images search results with a “Visit” button.

While users can still directly view an image by right-clicking the image result and selecting “Open Image in a New Tab”, it is more convenient and intuitive for users to click through to the landing page. Clicking on the image itself also takes the user to the landing page.

A study conducted by Anthony Muller of ZenSEM found that sites with large image catalogs (i.e. more than 100,000 images) saw a traffic increase of 37% each month after Google’s replacement of the “View Image” button. Muller also found that impressions and position were more or less stagnant, while clicks and clickthrough rates skyrocketed. This means that the topics these pages covered weren’t suddenly more popular or trending in the news, but that people simply had no choice but to click through to the page due to Google’s update and consequently increasing organic traffic.