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5 Ways to Optimize Images for SEO

Posted on May 8, 2014 in Search Engine Optimization Estimated reading time: 4 minutes

When marketers place emphasis on optimizing their content for SEO, they often focus on keyword research and making sure their copy is seen as search engine-friendly.

But many fail to focus on how their images are optimized. Ensuring images are search engine-friendly is an important and worthwhile piece of the SEO puzzle, and shouldn’t go without attention.

“I don’t care if my images rank, so what’s the point?”

This is a fair question. Many bloggers and publishers relying on stock photography use images that have already been indexed in search because others have published that same image before. However, implementing tactics that benefit image SEO don’t only increase image rankings. In actuality, image SEO can help boost rankings in the natural search results for your target keywords.

Before we can begin implementing tactics that serve image SEO, we must understand Google’s current image processing capabilities.

Below, is an abridged list of the types of information Google can read from an image:

-Shapes and basic objects (faces, animals, trees, etc.)
-Text that appears as part of the image
-All image metadata, including file names, ALT text, and EXIF data

While Google has the capability to extract this information, it requires far more processing power—especially compared to the information we tell Google about an image. For that reason, it won’t always pull these details and use them as ranking signals without a little help. But there are some powerful ways to increase effectiveness.

Here are five key ways we can optimize our images, using the image below as an example to reference.

1. File Names

Choose a descriptive file name for your image. Cameras will naturally output the manufacturers own taxonomy. They commonly appear in formats like “DSC_0040.jpg.” Unfortunately, this doesn’t tell us anything.

As a best practice, I always advise using a relevant, 2-5 word image name where the words are separate by hyphens.

Name the file with descriptive words about the image. Don’t use this time to be metaphorical or attempt to relate the image back the copy that will surround it.

2. ALT Text

ALT text stands for “alternative text” and represents an HTML field that can be used to tell search engines more information about the image. Use of the ALT text field is an absolute must for maximizing the search impact of images.

Use this opportunity to expand on the original file name, while adding context. Use no more than one sentence when considering ALT text field length.

Remember to accurately state what the image depicts while providing context at the same time.  This helps us transition from solely worrying about how an image will rank, to focusing on how we can use image metadata to rank textual content as well.

3. Image Captions

If Google finds an image without a descriptive file name or ALT text attribute, they may attempt to determine the contents of the image by looking at the surrounding copy. Captions are one location used to determine information about the image. The use of captions isn’t necessary 100% of the time, as the first two recommendations should take priority. Captions may also be used to credit the source if the image license deems it necessary.

4. Image File Size

A rising ranking signal over the past couple years has been site speed. That is, the time it takes a users browser to fully render all components on the page. There are many variables that impact site speed, but the file size of your images is one of them.

For most web content, opting for a web-formatted JPG image won’t sacrifice quality to the naked eye, and will provide low file sizes that browsers can render quickly. PNG can also be used, particularly if your image requires a transparent background. But if your image doesn’t require a transparent background, JPG is preferred due to lower file sizes.

5. Image Resolution

Contrary to popular belief, Google does take site design into account, as design aligns very closely with the user experience (UX). When sites provide a well-optimized user experience, Google may be more inclined to rank them above sites that aren’t as user-friendly to navigate.

With that in mind, choose image sizes that fit within the context of the site. For example, it’s not ideal to show full-screen images on a predominately text-based blog. However, full-screen or very large images may better align with the UX if appearing on a professional photography site.

By following these five tips, you’ll be closer to building out your SEO-friendly content marketing plan, giving your content the best chance at being discovered by the right people.