How to optimise images for SEO?

May 28, 2019
Google’s CEO, Sundar Pichai, had to sit through an interview with Congress, where he was grilled, and had to explain the basics of why image results of the US President were returned when anyone Googled “idiot”.

Meanwhile the rest of the internet was taking notes on how to optimize images for SEO, because who better to learn from?

The long and short of Pichai’s explanation was that; Google’s algorithm starts by matching image keywords to signals like popularity, freshness, relevance plus over 200 other signals, then evaluating said images using external raters – who try to follow objective guidelines – before assigning ranks. Trump’s “idiot” image had a lot of upvotes from Reddit, and one can argue that taking the matter to congress only increased its popularity.

Ordinary businesses and blogs don’t have the luxury of cultural/political storms pushing their site images up in Google results, but Pichai’s explanation – when applied diligently, still holds true for them. Here’s how you too can optimize your images for SEO purposes.

Use unique and relevant images

Before getting to the heart of the matter, you need to know that the uniqueness of your image can affect how well it ranks in Google Image search. As such, original photos generally perform better than free stock photos in SEO, because users are more likely to click on images they’ve never seen before.

That said, the pictures should be placed as close to the relevant written text as possible, and should evoke emotional responses from your audience so they stay glued to your page.

Select an appropriate format and size

There’s no such thing as a one-size-fits-all image format, instead you’ll have to rely on the purpose of your image. For company logos or website icons, use SVG or GIF formats, for large illustrations or pictures, JPEG’s the most common (but not ideal) format, if background transparency and image quality are a big deal for you, use PNG.

Each format allows you to resize without losing image quality. You can use Google analytics to see what screen size the majority of your audience uses, and pick a format that suits their device. However, our best piece of advice is simply to use a “srcset” attribute to make the image responsive to all screen sizes.

Small images load faster, which is great for SEO. So try to upload files in their smallest possible sizes, but use tools that compress pictures without compromising quality.

Use descriptive file names

Google’s gotten better at recognizing images, but that doesn’t mean you should leave your file name at Win_102567.jpg. If the image is of the Louvre Museum at sunset, your file name should be Louvre-Museum-Paris-Sunset. Notice how we suggested the key phrase “Louvre Museum” to be placed at the beginning of the file name, and not “Sunset in Paris”.

Use descriptive Alt texts

Alt text (or alternative text) are those descriptive highlights that show when you hover a cursor above an image.

It’s especially useful when images aren’t loading properly and allows those with visual problems (and Google bots who technically can’t “see” an image) understand the content of an image better. Sort of like an image title, but if you had an alt text, you won’t need one.

Image sitemaps

Seem a bit technical at first, but isn’t actually THAT complicated. At its most basic form, sitemaps allow Google to find images that might have stayed under the radar, and even allows you to recommend images from your site you’d want Google to crawl and index.

If you’re aren’t very tech savvy, there are plugins you can use.

Getting your images SEO optimized and at the top of search results can take a bit of an effort, but the conversion is always long term, and worth it.


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