The Five Core Rules of Optimizing Images for SEO

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When we talk about SEO, the focus isn't usually on optimizing images, but it's is usually on the text: is it organized and well written? Does it answer the question promised in the headline, and does it use headers and other elements to improve readability? In reality, image optimization is just as important as text optimization -- and maybe even more so, in a couple of instances. It goes far beyond the standard stuff like adding alt-text and descriptive filenames. Here’s everything you need to know about SEO for images.

Image SEO Rule #1: Pick the most relevant images you can find.

The quality and content of your image itself may not seem super relevant to SEO, but it might actually be the most important thing when it comes to page rank. We can’t know for certain what Google’s robots look for in your site’s images, but we can be sure that as Google continues to “focus on the user,” this will include both the relevancy and quality of a site’s images and illustrations.

The metrics for quality are fairly obvious: don’t use grainy or distorted images, use good lighting in your photos, adhere to some basic principles of good design. Relevancy is a little more nuanced, but as long as your images are serving to inform, entertain, or inspire your audience, you’re probably on the right track.

 Here's what a distorted image looks like (to avoid this, use the "resize" tool in your image editor rather than trying to resize manually).

Here's what a distorted image looks like (to avoid this, use the "resize" tool in your image editor rather than trying to resize manually).

Image SEO Rule #2: Make your own images when you can

Purpose-made images tend to give your site an SEO boost because you’re not duplicating content found elsewhere on the internet. As a B2B content marketer, I’ve actually stumbled upon multiple websites within an industry that use the same stock photography above the fold on their homepages -- it’s not a good look for anyone hoping to stand out in a saturated market!

The remedy is to commission, or create, your own original photos and graphics. Just one day spent with a photographer can garner hundreds of unique photos for you to use in your marketing, both online and offline. Alternately, you can find talented and affordable graphic designers on Upwork, Fiverr, or 99 Designs to create some custom stuff for your site.

While a professional photographer, designer, or illustrator can bring your entire website to a whole new level, you don’t need to hire this process out just yet (especially if you’re low on budget). Here are a few tried-and-true ways to create your own site graphics, even if you don’t have an artistic eye:

  • Use a template. User-friendly design apps like Canva or Venngage have built-in templates for just about any use case -- think social media posts, banner images, and infographics. All you have to do is pick the one you like, switch the colors to your brand’s colors, and fill in the blanks with your stellar content. Voila!

  • Edit your stock photos. One of the easiest ways to customize an image for your site is to make it your own through crafty editing. By cropping, flipping, or adjusting the colors or filters of existing stock photos, you can make something ordinary into something unique.

  • Use screenshots. If you’re creating how-to content around something super-technical, a series of screenshots can aid in your instruction, while also ensuring the originality of your visual content. A tool like Monosnap can help with both still shots and videos, though I like the good old-fashioned Snipping Tool in a pinch.

Image SEO Rule #3: Compress your images.

One of the simplest things you can do to dramatically improve your site is to compress photos before hitting “publish.” Kissmetrics research shows that it only takes two seconds of waiting for users to abandon a page. In addition, a mere one-second delay in page response can result in a 7% decrease in conversions. That’s huge!

To combat slow page load times, compress your images to the smallest file size they can be (without compromising quality). For some images, this may be a little as 50kb -- for others, like large banner images or infographics, you may have to settle for something around 1MB.

To compress, first, use an image editor to resize your image down to smaller dimensions. From there, use a tool like GIMP to export the image to a JPEG, where you can play around with compression levels to make sure you’re not reducing your image to a pixelated fuzzball.

A note on compression and file type: if you need an image to retain a transparent background, a JPEG won’t do. In this case, opt for a PNG-8, which will have a smaller file size than a PNG-24 but will still support transparency.

Learn More: Can SEO Hacks Alone Get You to the Top of SERPs in 2018?

Image SEO Rule #4: Use text to support your images.

Because your images, like your pages, can rank for certain keywords, each image’s filename should accurately describe the content featured in that image. Here are a few more pointers for using text appropriately to optimize your images:

  • Caption text: This is the text that appears below your image, giving it context. Poynter research says captions get 16% more readership than text, so whenever it’s appropriate, use captions!

  • Filename text: The file name of your actual image should be descriptive, with relevant keywords you’re hoping to rank for. Keep it short and sweet, too -- four to six words separated by hyphens is good.

  • Alt-text: You’ll find a spot to enter each image’s alt text in different places depending on your website building platform -- and it’s absolutely worth finding out where this spot is. The reason? The alt text tells Google what’s pictured in your image, because AI isn’t quite advanced enough yet to figure that out without your help. Providing alt text may be the difference between a top-ranking spot in a Google image search and falling pages below your competitors. Another reason it’s helpful to have alt-text is that if an image is too big or for some reason won’t display when a user opens your site, the alt text offers a description of the missing image.

  • Image link text: If your image serves as a link to another page on your site, the alt-text serves as its anchor text. Translation: just like the hyperlinked anchor text within your written content, alt-text should also contain keywords that could viably be search terms. For example, “product for lawyers” would be a poor choice of alt-text (or anchor text), while “workflow automation app for lawyers” would be much better.

Image SEO Rule #5: Make sure your images are mobile-friendly.

Though most website building platforms have mobile functionality built in these days, it’s a good practice to check and see what your site looks like on a mobile device. Sometimes, your images will resize or crop awkwardly on different devices, which will skyrocket your bounce rate. Test every page on a couple of different mobile devices to make sure you’re not alienating an entire audience with poor imagery.

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Finally, it’s worth mentioning that while you’ll hear all sorts of stuff about how people remember more of what they see than what they read, but doesn’t mean you should throw images onto your site for their own sake.

Like everything else in SEO, relevance will always trump rulesets. If your images don’t bring value -- whether to provide aesthetic beauty, additional context, entertainment or an alternate form of communication -- you’re better off leaving them out.