Image Optimisation Service

Image optimisation is important, for appering in image based searches and for on-site page load times. An important factor to consider when weighing the SEO value of your site.

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Using large images affects the user experience and image SEO, and it will cause Google to penalise your website ranking.

Low quality images will appear fuzzy, which will make your site look less polished and likely cause disengagement of users.

Our best-practice approach to image optimisation

Images resized for viewpoints
The use of image ‘Titles’ and ‘Alt’ Tags
Image types and the next-gen formats
Image meta stripping

Optimised Images Resized For Viewpoints

Images can have a huge impact on loading times, A large responcive image 1920 x 1080 (HD) displayed as a thumbnail still has to load the complete large image file. Three or four of these types of oversized images will vastly increase your page time. Appreciate the fact that 40% of users will abandon a site if it takes longer than 3 seconds to load!

Amazon did tests that showed they would lose $1.6 BILLION every year if they slowed down by just one second. Correct Image formatting is essential!

Image Alt and Title Tags

What is an image Alt Text?

Alt text (alternative text), also known as “alt attributes”, “alt descriptions”, are used within HTML to describe the appearance and function of an image on a page.

1. Adding alternative text to photos is first and foremost a principle of web accessibility. Visually impaired users using screen readers will be read an alt attribute to better understand an on-page image. Rule of thumb, improved accessibility = improved SEO

2. Alt tags will be displayed in place of an image if an image file cannot be loaded.

3. Alt tags provide better image context/descriptions to search engine crawlers, helping them to index an image properly.

EXAMPLE GOOD ALT BAD ALT

Poor alt text:
<img src=”bird.jpg” alt=”” />
Okay alt text:
<img src=”bird.jpg” alt=”cockerel” />
Better alt text:
<img src=”bird.jpg” alt=”cockerel crowing” />
Best alt text:
<img src=”bird.jpg” alt=”Red-crested cockerel crowing” />

Image Title’s

Image title attribute doesn’t (at present) have any impact on keyword rankings because search engines don’t crawl them. Having said that, image titles are displayed when your mouse hovers over an image in some browsers so it does improve user experience and accessibility.

Image Types and Next Gen Images

For images, the right format doesn’t exist; it depends on the kind of image and how you want to use it. As a rule of thumb

JPEG’s for larger photos or illustrations: it will give you good results in terms of colors and clarity with a relatively small file size;
PNG if you need to preserve background transparency, however PNG’s tend to be much larger file sizes so work best with smaller pictures and icons
GIF’s set to 256 colours, this older format is usually preserved for short animation, aka the animated gif.

Next-Gen Image Formats

WebP is a modern image format that provides superior lossless and lossy compression for images on the web. Using WebP, webmasters and web developers can create smaller, richer images that make the web faster.

WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34% smaller than comparable JPEG images at equivalent SSIM quality index.

Lossless WebP supports transparency (also known as alpha channel) at a cost of just 22% additional bytes. For cases when lossy RGB compression is acceptable, lossy WebP also supports transparency, typically providing 3× smaller file sizes compared to PNG.

Source: Developers Google

Stripping Meta Data From Images

Most images hold metadata stored within a file, which may include when the file was created and last edited.

Image files actually contain several file types within them. Different types of metadata are stored in different types of files. For example, in addition to visual data, JPEG images might also contain:

EXIF files, which hold information about the camera settings and manufacturer
IPTC files, which hold user-added metadata
8BIM files, which are added by Photoshop
ICC files, which contain information about embedded color profiles

Recommended image meta stripping tools

For Mac based O/S : ImageOptim
For PC’s: Gimp

EXIF files alone can include dozens of specific details such as when the picture was taken, the shutter speed used and whether the flash was enabled. Most of this information isn’t necessary for a browser to render the image, so it can be disposed of without worries.

Metadata can account for more than 15% of a JPEG file’s total size!

External reference articles & resources

SEO Hampshire

Technical Search Engine Optimisation for images, based in Hampshire.

With over 20 years of experience working within Media, Analysis & Web Development. Our sister site is called BoodleBobs

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Image Optimisation

Image optimisation, the process of reducing the file size of your images without sacrificing quality ensuring page load times remain low. It's also about machine interpretation of what an image via setting descriptive alt tags

Associated LSI Terms

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SEO Freelancer, imaage optimisation

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