While I'm not a huge fan of the overvisualised web, it's hard to deny the need for using images within your blog posts. Which is why you may already be stuffing your blog posts with photos, screenshots and other images. However, there are many considerations why images can be a troublesome way to convey your message, especially when it comes to search engine optimisation.
People are lazy, busy and love not to read words. Reading a thoughtful article, for most, is slower than glancing an image and moving on. And social media services, the visual kind as Pinterest and Instagram, and the mixed types like Facebook and Twitter, lean heavily on the power of an image. If you want to share an article on Pinterest, you must have an image (or video) to attach to the pin. You may have already heard that on Facebook photos gain much more likes than non-photo shares (videos, probably, even more). And similarly on Twitter, images increase clicks ReTweets and favourites. Your blog post images can also help (or harm) the search rankings of your articles. Additionally there are people who use the image search option to find articles about certain subjects. For those who blog cosmetics reviews I truly recommend looking into image search, and working on getting your images rank high in them.
Search engines are bad at reading photos. I was going to write that search engines can't read photos, but these days they kind of can. However, they are terrible at it and rely on some very simple ways to determine the content of the photo in regards of their relevance to searches. Never ever use images as a replacement of important text of your blog post. I often see people using images in place of the text, when they don't know how to use pretty fonts or other ways to improve the appearance of the text. This is a bad idea for SEO, since search engines cannot read that text and will ignore it. Firstly, the other content around the image affects to how the image is "seen" by search engines. If your blog post is about dogs and you use an image of cats in it, there's a chance that cat photo is found from searches relevant to the dog related queries. The image captions and image titles, plus other text around the image gives a context to your image. In the same way, doing an image search for someones name, may result to strangest images or photos of other people. Just because those images were found to be on pages and articles which also discuss about that searched person. Thus keeping your images relevant to the content (and the content relevant to the images) is a very good idea.
The second place to make the image more understandable for search engines is the image file name. For example, if you use an image straight from camera in your blog post, it will be named something obscure such as P1000003.JPG or 2016-01-09 18.21.37.jpg. In the latter there's at least a date and time, but even that doesn't tell much anything for a search engine. Google uses the filenames as the image's snippet in search results if they can't find other suitable text in the blog post to describe the image. Before adding the image to your blog post, describe the image content shortly or include the content relevant keywords. Either way, use the words in a describing way and don't just use a list of keywords. These days, I usually use two photos in my blog posts: One is a wider and shorter one, optimised for Facebook shares and others alike (used in og:image and other meta tags such like that) and the other one is the embedded photo, within the post. That one is slightly higher than it is wide, embedded inside the article, and it's been optimised for Pinterest. These images, which are not intended to expand the blog post content, I name usually somehow relevant to the blog post title, which itself I try and keep relevant and describing about the content.
As an example, the embedded, Pinterest optimised photo in this post is named blog-seo-optimising-images_merviemilia.jpg. It includes keywords relevant to my Blog post SEO series, to the post title and content itself and to my site name. If I would use an image to visualise something within the post, I would name it to describe what's in the image and how it's relevant to this post. As you can see, I use dashes and underscores to divide the words within the image name. The keywords within the image name should be relevant to the blog post content. Don't use irrelevant keywords ever, that only gets you penalised by search engines. Also don't try to stuff all the relevant keywords in your image file names. Try and keep the file names within a reasonable length.
The next point of optimising your images for SEO is using alt-texts. Some people also use title-texts, but they are not necessary for all the photos and they are not necessary for SEO if you are already using an alt-text. Using the same text as an alt-text and title-text is generally considered as a wrong thing to do, so in case you decide to use both, use different one in the title than the alt. Okay, with that disclaimer, here's how alt-text is added to your photo:
<img src="http://yoururl.com/path/to/media/folder/this-is-the-file-name.jpg" alt="This is the alt-text, which describes the image for the search engines and screen readers." />
If you use WordPress, or other similar platform for blogging, you can add alt-text to your media library. However, changing the alt-text in media library settings doesn't change it within your blog post (if the image is embedded to the text). It must be changed into the image tag. This can be done either by removing the image and adding (embedding) it again, or by changing it "manually" in the tag. In WordPress latter can be done by switching to the text editor (if you are using the visual editor) and changing whatever is written inside the quotation marks that follow alt=. See the previous example for more or consult your web developer, if you are unclear how to do this.
Alt-texts are very important for images on web. Not only for search engine optimisation, but also for making your blog posts more accessible. Screen readers, used by people who cannot see, read the alt-text as a description of what's in the photo. Additionally, if for a reason or another the images are not loaded the alt-text is shown in their place. Images may not be loaded for multiple reasons, such as if something goes wrong with the connection or the server in which your site is hosted. Many (mobile) users may even choose not to load images to save data or to speed up the load times. This is also why alt-text shouldn't be too long. Long alt-texts may be cut and shown only partially when images are not loaded. At least, make sure to add the important information in the beginning of the description.
One thing that's often forgot when optimising images for a website and SEO, is making file sizes smaller. This doesn't necessarily mean making the image dimensions (width and height) smaller, but making the file size smaller. Smaller file sizes make your blog post load faster. This is great for your blog readers and for keeping them from bouncing off the site immediately after noticing it loads really slow. This series, nonetheless, concentrates in blog post SEO. In 2010 Google announced they start to use site speed as a ranking factor. I will talk about this subject more in the next chapter of this series.
Either way, image optimisation includes optimising the file sizes in your blog posts. This can be done in many ways. You can optimise images in the app or service you use to edit your photos. Different applications offer different ways to optimise images. In Photoshop there's a "Save For Web & Devices" option, in which you can choose between various ways to pack the image and preview quality settings. Canva also has a "Save for web" option. I highly recommend resizing your images, if their dimensions are very big. For example, the photos straight from your camera usually have huge dimensions too. Using the right image format also affects the image size. For some photos PNG is the best, and others JPG (or JPEG) works better. I recommend learning the basics of the image formats and trying which works best for your images, keeping the image quality good, but also making images as small as possible. There are also many online tools, plugins and modules for your blog platform, and apps you can use to pack images without affecting their quality. For WordPress I recommend plugins called WP Smush and EWWW Image Optimizer. In addition to saving the images web optimised in my Photoshop, I use a free Mac app called ImageOptim to clean and pack them further. On my Drupal site I also have a module called Image Optimize. Other compression options include free web based services such as TinyPNG and TinyJPG. These two are also available as Photoshop plugins.
You can also use XML sitemaps to help search engines to find your images. According to Google image sitemaps for this. However, this isn't a necessary step for your blog, because the images are already found in your blog posts (especially if you follow the guidelines above).
Optimising images for blog post SEO includes optimising the file names, alt-texts and file sizes. The keywords included in the image file names and alt-texts should be relevant to the content of the blog post. Also the blog post content itself is used to determine what an image found on the same page is about, so the image itself needs to be somehow relevant to the content. By optimising the images for search engines you make it easier for the search bots determine the relevancy of the image to the searches. And hey, you also provide a much better experience for your audience. When people love your site, search engines love it too.
Blog post SEO series
- Targeting long tail keywords
- External and internal links
- Optimising images
- Page speed
- Content matters
- Meta tags
See all the articles in Blog post SEO.