e-testing Blog

Using the WebP image format – When, if and how to migrate.

WebPGoogle has released WebP, a new image format which can significantly reduce image sizes – around 30% over JPEG. Have a look at Google’s gallery to see the difference for yourself: https://developers.google.com/speed/webp/gallery

Lean images should mean faster performance which could give your site that competitive advantage. How much faster will depend on compression choices, but technical discussions aside, there are other factors to consider before making the move.

The format isn’t universally supported. As you would expect, Google got their own house in order first. The current supported browsers and platforms are:

– WebP lossy support

  • Google Chrome (desktop) 17+
  • Google Chrome for Android version 25+
  • Opera 11.10+
  • Native web browser, Android 4.0+ (ICS)

– WebP lossy, lossless & alpha support (libwebp v0.2.0)

  • Google Chrome (desktop) 23+
  • Google Chrome for Android version 25+
  • Opera 12.10+
  • Native web browser, Android 4.2+ (JB-MR1)

That leaves a large market share missing. Google have provided sample code to help detect browser support and allow alternative images to be used. So, a mechanism is in place but the additional processing to deal with non-compliant browsers could itself be a performance overhead. Moreover, you will need to test the code change and the impact it has.

It doesn’t sound so inviting now, does it?

Nevertheless, there almost certainly will come a point where all browsers will support it and so it is more a question of when rather than if.

Those who jump at the right time could take the competitive edge so how do you know what the performance impact will be on your site and what the experience will be for users who don’t have a compatible browser?

There isn’t one simple answer – it depends on your implementation.

However cloud-based virtual platform providers such as Sauce Labs and BrowserStack offer a means to run automated and manual tests on a hundreds of platform and browser combinations. Similarly, performance monitoring tools such as sitespeed.io, when correctly used, can provide clear insight into the impact of the change. And of course, when it comes to finding the unforeseen consequences of a change, there is nothing to match a seasoned test analyst.

If you would like to discuss image migration or any other website performance based issues at your organisation, please get in touch with a member of the e-testing team. You can also use our online performance testing quotation tool to provide your requirements. 


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