Image SEO: improve your Google ranking with image op­ti­miza­tion

If you want to improve your website’s position in the search engine results pages, most on-page measures center on the op­ti­miza­tion of content, metadata, link structure, and source code. The images featured on the website, despite being an important aspect of content, are often neglected during SEO measures. However, extending your op­ti­miza­tion tech­niques to include images is generally pos­i­tive­ly rated by Google, and can therefore both generate ad­di­tion­al traffic for your website and influence the user’s rating. This, in turn, has a positive effect on the website’s position in search results, proving that, with good image SEO, you can kill two birds with one stone.

These days, there are not too many websites that don’t contain any images. Without some kind of visual appeal, it’s usually pretty difficult to maintain the user’s interest – as the old saying goes, ‘A picture tells a thousand words’. For online shops, busi­ness­es, or in­di­vid­u­als ad­ver­tis­ing goods and services on the web, good images are a key element, without which it would be virtually im­pos­si­ble to attract customers. High-quality images ensure a better user ex­pe­ri­ence and attract attention; for these reasons alone, it’s worth investing time and money into op­ti­miz­ing your images. In­fo­graph­ics are par­tic­u­lar­ly popular, as these also often generate useful backlinks. 

Retention times and con­ver­sions increase when the content is enhanced by images, while the bounce rate is reduced. Technical quality is also a decisive factor, in addition to the visual quality of the images. When it comes to gen­er­at­ing traffic from mobile devices, it’s par­tic­u­lar­ly important for the images to have a short loading time. Website owners who make an effort to create strong images in a suitable format are rewarded with a good rating by Google, which sub­se­quent­ly improves the ranking of your entire site.

In addition to the normal search function, Google offers a targeted image search, which is of central im­por­tance for the search engine op­ti­miza­tion of images. A good position in the image search results pages can pay off just as much as on normal results pages. While many users will end up on your site by searching directly for their desired product or service, this can also be achieved by having many at­trac­tive images appear in the normal results pages. According to a study by Search­metrics, Google plays about 40% of the entered search requests matching pictures. In this way, you can position yourself with good SEO images in the standard search. One study by German content marketing platform Search­metrics suggested that Google displays matching images for around 40% of all search queries. This allows you to improve your position in the standard search with good image SEO.

In 2001, the search engine giant, Google Images, published its own, image-oriented web search through which users could search for graphics and photos. The starting point for the search results is the image index. This is a database that contains all images found by Google with the help of crawlers – automatic search programs – that store them on their own servers. Googlebot images are the crawlers re­spon­si­ble for image indexing and since the end of 2010, part of the default Googlebot. In its infancy, the library included around 250,000 indexed images, but after four years, the brand has already exceeded the one billion mark.

The crawlers are unable to read images visually, so they assign content the­mat­i­cal­ly according to their re­spec­tive HTML codes. In doing so, the bot scans the text en­vi­ron­ment and the image’s <img> tag itself to determine which keywords are relevant to the image. Read on to find out which factors are relevant to Google rating and how to get the most out of them.

Getting the right file name

Your image’s file name can help the crawlers classify images the­mat­i­cal­ly – namely by referring to the name of the topic. Often people do not put much thought into naming their image files, so it’s not uncommon to see file names like picture01.jpg or img10.jpg. In doing this, you will not be aware of any specific dis­ad­van­tage, but a vague file name like this will sig­nif­i­cant­ly reduce the chances of your images being found by crawlers. With a file name like dal­ma­tions.jpg, on the other hand, your images will have a far higher chance of being detected and assigned to the ap­pro­pri­ate category. Avoid any special char­ac­ters, as these could prevent the image from being displayed. In­di­vid­ual terms can be separated with a hyphen, which will be in­ter­pret­ed by Google as a space.

The alt attribute: de­scrib­ing images in text form

One of the most important ranking factors in image op­ti­miza­tion is the alt attribute, also known as the alt tag. This is an attribute of the <img> tag, which is used to embed images into an HTML document (‘alt’ here being short for ‘al­ter­na­tive’). The ‘alt’ attribute contains the text that describes the image and is an al­ter­na­tive display for the site visitor if the image cannot be displayed due to technical problems or special browser settings. Many programs for visually impaired people also use the al­ter­na­tive text to describe the image. For this reason, the alt attribute is a mandatory task for im­ple­ment­ing barrier-free websites. Al­ter­na­tive text is an excellent way for Google crawlers to un­der­stand and cat­e­go­rize an image. You should therefore try to create a de­scrip­tion that describes the image as ac­cu­rate­ly as possible and embed important and relevant keywords that are ap­pro­pri­ate to the context. However, you should refrain from using filler keywords, as this can quickly lead to Google marking your website as spam, resulting in a lower ranking. Example of a well im­ple­ment­ed alt attribute:

Example of a bad alt attribute that would attract a negative rating:

Content-rich tooltips (title) and image captions

The optional title attribute is another attribute of the <img> tag: an ad­di­tion­al way of de­scrib­ing the re­spec­tive image. Your website visitors see the picture title presented as a tooltip when they move the mouse pointer over the picture. This serves as a further item for research and eval­u­a­tion for the search engine bots. It’s a good idea to use the same keyword for the title attribute as for the alt attribute, as con­flict­ing keywords can also lead to a negative rating. If an image is linked to a click action, for example a link to another (internal or external) page, or zooming in to the picture, you should only use the title to describe the re­spec­tive action.

Im­ple­ment­ing an image caption is also useful, even if it’s as­so­ci­at­ed with a little more work. This short text, which users au­to­mat­i­cal­ly see as opposed to the tooltip, provides another platform for your keywords, although it’s not featured in the <img> tag. Since the launch of HTML5, the elements <figure> and <fig­cap­tion> have been made available for this purpose, and can be used to describe mul­ti­me­dia content, including the cor­re­spond­ing text. Pre­vi­ous­ly, it was necessary to revert to the more general <div> container. To create the desired visual pre­sen­ta­tion form, you also need ap­pro­pri­ate CSS in­struc­tions. Image captions are also an ideal way to provide license in­for­ma­tion so that other users can re­dis­trib­ute your images, including their names, or use images that are as­so­ci­at­ed with the ap­pro­pri­ate copyright notices.

Ap­pro­pri­ate context

Search engine op­ti­miza­tion of images is closely linked to the un­der­ly­ing context. It’s rarely ad­van­ta­geous to optimize images with the above­men­tioned measures if they have no relevance to the website’s content. The crawlers know that an optimized image of a tomato will rarely be relevant to an article about snow­boards on a snow sports website. However, such an image has far higher chances of being relevant to a review of vegetable varieties on a nutrition page. To ensure your pictures get a good rating, they should fit the context of the re­spec­tive page as far as possible. But in image SEO, bots gather much more in­for­ma­tion than just the text that directly follows the image. The following text com­po­nents are equally as important:

• the website’s title,
• the main headline (h1),
• the sub­head­ing (h2, h3, h4),
• the image caption
• the title attribute (tooltip)

The crawlers examine and rate the entire structure, giving a good ranking to the images that fit the content and keywords of your web project.

When im­ple­ment­ed correctly, the different op­ti­miza­tion methods listed above have a positive effect on the users’ surfing ex­pe­ri­ence. They receive suitable search results for their queries and receive detailed or al­ter­na­tive in­for­ma­tion about the images. In addition to for­mu­lat­ing a good keyword strategy for the title file name, and al­ter­na­tive text, further methods for improving the user ex­pe­ri­ence include:

• Use high-quality images: High-res­o­lu­tion images have a far greater effect on your visitors than blurry or unclear images. They are also displayed far more clearly in the Google search results thumb­nails and more fre­quent­ly linked by other web­mas­ters. But make sure your images retain a good balance of quality and file size and compress them using one of these free tools.

• Finding an optimal placement for images: Images serve to il­lus­trate your web project and make it stand out from the crowd, which is why an optimal po­si­tion­ing is in­dis­pens­able. Users will often not bother to scroll to the end of the page, so it’s generally a good idea to place graphics, photos, and images at the top of the page, where possible.

• Specify di­men­sions: Web browsers can begin to display your page before loading any images – provided the di­men­sions of the images are known. If you have entered the image’s height and width, the remaining elements can start to be built-up around a place­hold­er to be noticed more quickly. In­ci­den­tal­ly, Google generally rates images in a landscape format (4: 3) better than images in portrait format.

The perfect mix of quality and stable per­for­mance is par­tic­u­lar­ly sig­nif­i­cant for the growing mobile sector. Mobile devices normally have far less broadband than desktop PCs, making speed op­ti­miza­tion es­pe­cial­ly important. Long loading times can quickly result in a high bounce rate.

As with tra­di­tion­al search engine op­ti­miza­tion, the results of your efforts will not be im­me­di­ate­ly apparent with image SEO. To keep up with the com­pe­ti­tion, you have to assume that other website owners have optimized their images with selected themes and keywords with pictures. Various long-term factors also play an important role for the image ranking and these only come into play after a few months. Many of these factors can be in­flu­enced by normal off-page measures, while others are linked to the quality, general success, and relevance of your web project.

• Internal and external link structure: With a good link structure, your images (and therefore your web offer) promises authority and pro­fes­sion­al­ism. Par­tic­u­lar­ly with the help of in­fo­graph­ics, strong links can result in an improved ranking in the long term.
• Multiple ap­pli­ca­tions: In using one set image on several pages of the same domain in an ap­pro­pri­ate context, Google will rate it pos­i­tive­ly when you always reference the same file path.
• How current the image is: The exact influence of the age of your pictures can only be spec­u­lat­ed. Older images appear to be favored by Google – pre­sum­ably due to existing link struc­tures; on the other hand, the search engine giant is steadily at­tribut­ing more value to new content, which is why younger images, par­tic­u­lar­ly sur­round­ing current topics, seem to gain in value.
• Click-through rate: Keywords and links are strong factors that Google honors ac­cord­ing­ly with good ratings. However, the Google algorithm can’t ascertain the relevance of an image quite as well as humans can. For this reason, the as­sess­ment is also in­flu­enced by how often users click on an image featured on the search engine results pages.
• Relevance: One ranking factor that is very difficult to measure is the overall relevance of your images. It’s assumed that Google wants to display specific search results with pictures that are relevant to the page content. The algorithm ul­ti­mate­ly de­ter­mines this by way of several factors, such as the number of links, or the context of the images.

Op­ti­miz­ing the images on your website for Google can have a positive effect on your website in many ways; first and foremost, you're improving your Google Image Search ranking, which is one of the most widely used platforms for finding the right website. With a little bit of luck, a high ranking should also mean your pictures get featured in the regular web search – re­gard­less of the general clas­si­fi­ca­tion of your web project. For practical purposes, thorough SEO for images also has a positive effect on this ranking, because it is linked to an improved user ex­pe­ri­ence and ac­ces­si­bil­i­ty.

The search engine op­ti­miza­tion of your images can therefore sig­nif­i­cant­ly increase your pop­u­lar­i­ty and visitor numbers to your page, who might not have found your website otherwise. Don’t be put off if image op­ti­miza­tion is a big challenge at first; it will take less and less time to optimize the <img> tag the more this becomes part of your routine. And with some ex­pe­ri­ence, you will soon get a perfect symbiosis of images and text. Suc­cess­ful image SEO methods can be used again in the future to use image searches as an ad­ver­tis­ing platform. Par­tic­u­lar­ly when it comes to highly com­pet­i­tive keywords, eye-catching, al­ter­na­tive images can make a world of dif­fer­ence.

All the steps covered in this guide are suitable for current methods by way search engine’s crawlers and al­go­rithms detect your website images. However, with Google's con­stant­ly evolving tech­nol­o­gy, it’s very likely that there will be ad­di­tion­al factors to record and classify images in the future. For example, in 2014, Google announced that EXIF data could po­ten­tial­ly be a ranking factor on its ‘Google Web­mas­ters’ YouTube channel:

The digital metadata, which includes, among other things, in­for­ma­tion about the pho­tog­ra­ph­er, the copyright, or the date and time of snapshots, could also help to display even more accurate results to the search engine’s users.