SEO is not only about optimizing written content. With the increasing dominance of visual content online, there have been new opportunities for increasing a website’s search traffic by optimizing images and videos.
According to HTTP Archive, images make up on average 54% of a total webpage’s weight. So when it comes to optimizing your website, images are the best place to start! By optimizing your images, this gives your website an additional opportunity to be found via image search, and a good logo or some eye-catching graphics can be just as effective at attracting visitors to your website as your written content.
The size of your images can have a huge impact on your website’s overall site speed which is an important search ranking factor, and large, high-resolution images are one of the biggest reasons for slowing down a website’s load time – particularly on mobile. Google’s algorithm is all about providing the best experience for Google users, so pages with longer load times are penalized. This applies to images as well. The larger an image is, the longer it will take to load which could negatively impact your image SEO.
The best option when it comes to image optimization is to use images that are exactly the size that you need and not any bigger. Many platforms will allow you to upload images of almost any size and will then squeeze the larger images down to fit the provided space.
Image File Type Options
There are three main file types you’ll want to focus on for saving images optimized for the web: PNG, JPEG, and GIF. Each file type has its own strengths and weaknesses, and it is very important to know and keep these in mind when saving an image.
JPEG – can adjust the quality level for a good balance of quality and file size.
PNG – produces higher quality images, but also has a larger file size.
GIF – only uses 256 colors. It’s the best choice for animated images.
Working with JPEGs
JPEGs are the most popular file type for images on the web. They’re perfect for photographs, or complex images containing lots of colors, shadows, gradients, or complex patterns. JPEGs handle these type of images well because JPEGs have a huge color pallet to work with.
JPEGs can also be saved in high quality, low quality or anywhere in between. This allows you to adjust and save the image exactly how you want, balancing both the quality and file size.
A JPEG should be used in any situation when it’s important to have a small file. Beyond the initial saving as a JPEG, there are tools that will allow you to shrink the file further. This is useful for web images, as the smaller size will increase the speed at which the page loads.
Working with PNGs
PNGs are another popular file format. Within Adobe Photoshop, users have the option to save PNGs as PNG-8 or PNG-24.
PNG-8 has a limited color palette of 256 colors. While the image size is smaller, this won’t be a good option for complex images or photographs. PNG-24 provides a much higher quality image but comes at the cost of a larger file size.
Most importantly, PNGs can handle transparency which is one of the biggest differentiators between PNGs and JPEGs. An important benefit, and oftentimes deciding factor for using a PNG file, is that – unlike a JPEG – they support transparency. This allows you to have a transparent background around an irregular-shaped object and avoid a white (or any other colored) box outlining your image. If you require transparency, you will want to opt for a PNG.
Working with GIFs
GIFs are an option for small image sizes where only a few colors are needed. Much like PNG-8, GIF files are restricted to only 256 colors, but because of this should never be used for product photos.
Saving Images Properly
As mentioned, large images take a website longer to load. Seeing as 47% of users expect a webpage to load in under 2 seconds, and 40% will abandon a page that takes more than 3 seconds to load, it’s important that your images are small enough to ensure a speedy site!
These are ways to save your images so they’re compressed and properly optimized for your website:
Save Images for Web
One of the easiest methods of reducing the file size without significantly reducing the quality of your images is using Photoshop’s ‘Save for Web’ function.
You simply open your image in Photoshop and go to File > Export > Save for Web (Legacy). A window will appear which will allow you to choose your export quality. We typically recommend a quality of 60 works best because it drops the file size with no noticeable difference in quality.
Compress Images for Web
Image compression apps are another easy way to reduce the file size of images. These types of tools remove hidden data in image files like additional color profiles and metadata – geolocation of where the photograph was taken – that aren’t needed. These tools provide a quick and easy way to reduce files size without losing any image quality.
The name of your image file can help search engines discover your content in context. This is where keywords first enter the picture – literally.
If you’re uploading a photo of nature photography, a relevant filename like nature_photography.png has a better chance of ranking well in search than DSC_3214.png. If it’s possible to be even more specific, such as San-Diego-Botanic-Garden.png, then that’s even better for SEO.
Think about how your users search for products or services on your website. What naming patterns do they use when they search? If you don’t enter a separate title for your image upon upload, the filename will also serve as the image title, which makes it all the more important to be clear and accurate with your filename.
Alt attributes are the text alternatives to your image which will appear if your image fails to load. Because web crawlers don’t have eyes, these alternatives are what search engines see instead of an image, making them important for both accessibility and SEO.
The alt text and title text tag fields are the best places to put any keywords relevant to your image.
The title text is essentially the name of your image, and as such serves a very similar purpose to your image name. The main difference is that it needs to be human readable as well as machine readable – so use spaces to separate the words in your image instead of underscores or dashes.
This is the field that describes what your image depicts. Alt text can help search engines work out not just the content of an image but the topic of the surrounding text which makes it just as important.