Many Websites include images as part of their core elements. Unfortunately, all too often such images are not optimised properly, increasing load times and doing little for search engine visibility. Here are a few ways to optimise images not only for much improved load times, but also to assist SEO efforts as a whole.

Image Dimensions

Using the right - exact - dimensions for images can significantly reduce load times. Rather than relying on browsers or your CMS to resize images to fit, load images of exactly the right, required size in the first place.

Image File Type

The most commonly used file types for images on Websites are JPEG and PNG. Depending on the subject matter and size of the image to be used, either of these options may offer different benefits. JPEGs are typically of advantage for large photos, while PNGs are often beneficial for images containing text, or comparatively small images. 8-bit PNGs are best for simple images with minimal colours.

The best bet is usually to save an image in both format and select the one that offers the greatest clarity at the smallest file size. Most editors also offer other options of reducing file sizes without losing too much quality. In addition, removing unnecessary meta-data - such as camera/ lens types, dates, and so on - can also reduce the size of image files.

Image Description

The final step in optimising an image - predominantly for SEO purposes - is to provide it with adequate descriptions within the HTML tag. This is done in three ways.

File Name - This assists search engines in understanding what is depicted in the image. A brief description of the image - using hyphens instead of underscores when it is necessary to break up words - is perfect as the file name.

Alt Attribute - Also referred to as the alt tag, the alt attribute provides an image description to be displayed if the image can not be loaded for whatever reason, or for viewers using screen readers. This text is usually also displayed when the mouse is placed over the image. Search engines - and in particular Google - place much weight on alt attributes of images.

Title Attributes - Title attribute text usually comes into play when an images doubles up as a link. Typically used to add extra information, this text should be different to the alt attribute text. It will be displayed when mousing over the displayed image or - in screen readers or if the image can not load - the alt text.