Importance of Image Optimization for SEO
As the saying goes, “a picture is worth a thousand words”. Approximately 65% of people are visual learners, and adding relevant and attractive images to your website can be very effective at increasing user engagement with the page.
Furthermore, according to a search engine ranking study by Backlinko, content with at least one relevant image significantly outperformed content without any images. The same study found however, that using additional images did not make much difference. When you include images on your website, it is critically important to optimize the images for SEO, particularly if you’re an eCommerce site. This will ensure that you get the ranking boost that comes with using images in your content.
Image optimization is essential for ranking high on the search engine results page (SERP). It is important to note that the search engine spiders cannot read or understand the content of a picture. You must explain what is in the image using textual content. In addition when using images, don’t simply add an image for the sake of it. It needs to be something that reflects the topic of the post. This is because an image that is surrounded by contextually relevant text ranks better for the keyword it is optimized for.
Note that a significant amount of traffic can come from image search, and the number of people competing effectively for that traffic is much lower than it is in general web search.
Topically Relevant Keywords
Using topically relevant keywords to name your images can have a powerful impact on the search ranking of your website in relation to the images. For example, if your website is about cars and all of the images on your site are well-optimized using relevant keyword-rich names, all things equal, this will significantly increase your website’s overall search ranking for those keywords in image search and universal search. Google will take the topical relevance that you’re building with the image and associate it at the domain level, thereby increasing the search ranking of the website it is linked to for those keywords.
You should have a proper copyright license to display the images found on your site so that you don’t reported for copyright infringement. Google has a copyright removal notice penalty, which affects sites with a significant number of valid copyright removal notices lodged against them. Google has confirmed that such sites would be penalized and down ranked in the search engine results for related keywords.
Optimizing for Image Search
The Image Filename
The way you name your images is particularly important, more so if you’re an eCommerce site. In order for your product images to appear for relevant searches on Google Image Search and in Universal search results, your images have to be optimized for SEO using relevant and descriptive keywords.
When establishing relevance to a search query, search crawlers will not only crawl the text on your web page, they will also read the filename, alt tags, the image’s caption and any surrounding text that can provide clues as to what the image is about. This is why it is essential to optimize your image because this will play a key role is establishing relevance to a specific search query.
Naming the File
When indexing an image, the first place that search engines will always look at first of all is the image filename. They’ll want to see whether the name provides any clues as to the content of the image. This is why it is important to use contextually relevant images and descriptive filenames that include your primary keywords for your images. The image filename provides the opportunity to provide meaningful information for search engines as well as users.
Search engine spiders cannot read images, and will look for clues when trying to understand the relevance of the image to the webpage’s topic, and the filename is one of the first elements it will look at. This is why the filename should have the webpage’s most important, relevant keywords.
For example, if the image in question is that of a red 2004 Toyota Camry that you are selling on your e-commerce website, name the file something like red-2004-toyota-camry-for-sale.jpg, rather than using an ambiguous name that makes no sense, such as DSC12345.jpg or even just red-car.jpg.
Given the fact that there are millions of car models, this type of naming convention tells the search engine nothing really helpful at all about the image, and you are passing up the opportunity to include keyword-rich text that could drive people searching for a red 2004 Toyota Camry to your site. This will help increase the on-page SEO and overall website ranking of that page for relevant searches.
Equally, if you have images that represent a service that you offer, you should name the image after the specific service. For example, if you’re a carpenter and have carpentry-related images on your site, you should name the image after the specific carpentry service that you offer.
So, if you offer loft conversions, kitchens, plastering, etc., you should have different images for each of these services and name each image using keywords that represent the specific service that you offer, instead of having a single image with a general name such as “carpentry-services”. This will help you rank for more specific services as well as for general services.
The Title Tag
The title tag of an image shows up whenever you hover on the image with your mouse and tells users what the image is about. If you have an image that represents the service you’re currently offering, you should use unique, descriptive keywords to name the title after the specific service that the image represents.
For example, if you’re a Hendon-based plasterer, you could have a picture of yourself in action as a plasterer with the following title: “Plastering services in Hendon, London.”
Geotagging Your Images
Geotagging is the process of embedding location information to specific photos by placing your photos on an exact location on a map in order to help search engines see the association between that photo and a specific location that you added as part of your metadata. The position’s longitude and latitude are stored as two numbers in the image file’s EXIF data.
Captions and Descriptions
Most webmasters fail to add a caption and description to their images, but doing so can give your site a slight ranking boost. Furthermore, including descriptive text either above, below or next to the image will help increase the contextual relevance of the image. This will reinforce the relevance of the web page to the page’s topic and help increase the ranking of the web page for the keywords you use to optimize the image.
A descriptive caption provides data to the search engine spiders that they can read and index. It also helps communicate your intended meaning to users. How much text you actually include next to a particular image will depend on the size of the image. Large images can contain longer text descriptions than smaller images. Since In this sort of scenario, you should explain the picture with at least a sentence of text.
You can add additional information to your images within your content management system, or manually within your HTML code. If you’re using WordPress, once you have uploaded your image, double click on the image you’d like to update. On the right side of the image, you’ll be able to add additional information to the image.
Increasing the Relevance of an Image
The most effective way to increase relevance of an image to a particular search query is by adding relevant keywords to as many elements connected to the image as possible. This includes the filename, alt text, caption, surrounding text and any inbound links to the page. This will ensure that the search engines have no doubt as to what the image is about. In addition, you can add schematic mark-up to your images to increase the chances of the image appearing in the Google Knowledge Graph.
For example, to optimize an image of a red Toyota Camry 2012, you’d add the following code to your HTML: <img itemprop=“image” alt=“Red Toyota Camry 2010″ src=”http://example.com/red-camry.jpg”/>.
Note that WordPress will strip out your schema code, but you do 2 things to overcome this problem:
- Disable visual editor
- Use Post Snippets plugin which will allow you to create short codes that you can insert into your pages. That way, WordPress won’t strip those out.
You can also add a lot of information to your images such as where the photo was taken, what date, by whom, etc. Adding schema to your images can be particularly useful for local businesses without physical locations in the areas that they serve. On-page optimization in the form of schematic markup is very important for ranking in those locations where you don’t have a physical address.
Before naming your images, it is good practice to always perform your keyword research so that your files are named according to how your potential customers refer to the most important products you sell. This may increase your chances of showing up for relevant searches.
Using Spaces and Underscores
Avoid spaces and the underscore when naming your files. Search engines tend to view the underscore as its own character, so if you name the file Toyota_camry_2010.jpg, the search engine will interpret it as toyotaxcamryx2010, which may be difficult for some search spiders to understand, and you will miss an opportunity to use your keywords when a search engine spider reads it. This is because underscores are not recognized as a separator by search engine spiders:
According to Google, “Consider using punctuation in your URLs. The URL http://www.example.com/green-dress.html is much more useful to us than http://www.example.com/greendress.html. We recommend that you use hyphens (-) instead of underscores (_) in your URLs.”
Leaving spaces in the filename is also bad practice, as the search engines tend to replace the space with percentage signs. It is much better to use periods or hyphens than to use spaces. Using periods or hypens means that you can have files that look like this:
Note that even without spaces, periods, or hyphens in your filenames, Google searchbots can actually parse out up to 500 words that are concatenated. However, using hyphens and periods in your filename is recognized as good practice, and it definitely makes your filename more SEO-friendly.
The Alt Attribute
The alt attribute (also known as alt tags) displays what text should be shown if, for any reason, a given image is not viewable by visually impaired users and search engine spiders. Typically, when you add an alt tag to an image, try to use the target keyword of the web page to increase the relevance of the page. In addition, include relevant text in the paragraph directly before or after the images. This will help provide search engines with further context and is what the user most closely associates with the image.
Matt Cutts discusses the alt tag in this video:
<iframe width=”420″ height=”315″ src=”https://www.youtube.com/embed/3NbuDpB_BTc” frameborder=”0″ allowfullscreen></iframe>
Given the fact that Google has confirmed that the alt attribute is taken into consideration when trying to understand an image, it is important to ensure that the alt attribute concisely and accurately describes your image. For example, if you have an image of a Galaxy s6 Android smartphone, use an alt tag that best describes the image, which in this case is “Galaxy s6 Android smartphone”.
Here’s what the image tag will look like:
<img src=“Galaxy s6 Android Smartphone” alt=“used black Galaxy Android smartphone ”>
If the image is a hyperlink to a specific page, you would use a title attribute which should describe what will happen when the image is clicked on. For example, if the size of the image will increase when the image is clicked, the title should say something like “Click to enlarge”. You could also be more detailed and say “Click to enlarge image of Galaxy s6 Android smartphone”.
Writing Alt Attributes
When writing Alt attributes for images, make the length proportionate to the image’s size on-screen. Create a brief Alt attribute for a small image, and longer ones for large images.
The web page’s title tag, the H1 heading tag, the on-page content, and links to the page are all factors in image ranking. For example, if you have a single image on a page and it is a picture of the London Eye, if it is reinforced by the title, heading tag, and page content which all support that, the search engines’ confidence in the content of the image increases.
Optimizing alt tags is important to get right, and over-optimizing an alt tag could see your site penalized. Stuffing the alt attribute with irrelevant keywords would be tantamount to search engine spam, and could attract an algorithmic penalty. For this reason, it is important to ensure that you are only using your target keywords in the alt text because it is contextually relevant to the image.
Additional Alt Tag Rules
- When writing your alt tags, use keyword-rich, descriptive words.
- If your product has a product number, use this in your alt text.
- Do not keyword stuff your alt tags. For example alt=“Galaxy S6 Android Smartphone for sale. Cheapest Price. Buy Now”. This type of thing will get the entire web page penalized for spam.
- There’s no need to add alt tags to things like icons. Doing do may render the page susceptible to the over-optimization penalty.
Optimizing Your Image Dimensions
When selling a particular product on a website, it is normal to feature the product from various angles in order to increase its saleability. For example, if you’re selling a car, it is normal to include shots of the interior, dashboard, rims, engine, etc. You can capitalize on this opportunity by creating unique alt tags and filenames for each image you upload.
For example: Img src=“Toyota-Camry-2010-Black-Leather-Interior.jpg” alt=“Toyota Camry 2010 Black Leather Interior”
By taking advantage of these additional image dimensions, you will be showing up for more relevant searches, which will ultimately increase the search ranking of your site.
Optimizing the File Size
Load times are an important ranking factor. The faster the loading time of your site, the quicker it is for the pages to be indexed by the search engine spiders. However page loading time also affects your bottom line because it is an important part of the user experience. In fact, according to Kissmetrics, a 1 second delay in page response can result in a 7% reduction in conversions. Furthermore, Amazon found that if their pages slow down by 1 second, they lose $1.6 billion a year.
Essentially, the larger the image, the longer it will take the associated web page to load, especially when you display the large image as a thumbnail. The entire image will still have to be loaded even when it is displayed as a thumbnail. This is why it is critically important to ensure that the image file size is reduced to the lowest file size possible before uploading, while retaining quality. A good rule of thumb is to keep your images below 70KB, especially if you have lots of images on your site. Note that even though WordPress provides the images in multiple size, this doesn’t mean the image’s file size is optimized. The file size needs to be reduced before uploading the image to WordPress.
How to Reduce Image File Sizes
There are numerous free tools you can use to reduce image file sizes:
- GIMP: This is an open-source, free image editing software application that can be run on most operating systems.
- ImageOptim: This is a free tool that allows you to resize and optimize your images on the web.
- JPEGMini: This is a photo optimization application that reduces file sizes by as much as 80%.
- PunyPNG: This is a PNG compression and image optimization tool.
- Pixlr: This is a user-friendly photo editing tool that you can use to edit your photos even on your smartphone.