[gcr]

But they did compare to JPEG as a baseline...?

    > On average, our customers have seen images that are
    > half of their JPEG equivalent file size using these
    > formats! The same quality image, half of the size.

Other than this textual statement, I don't see any comparisons. I only see absolute file sizes.

[zacman85]

We used the existing image requests as a baseline. So the numbers we are reporting are specifically for the images that are being served in established formats (e.g. PNG and JPEG) measured against their equivalent requested WebP and JPEG XR variants. We then measured the percentiles of savings for these images. 98% of images in our test customer base saw a 18-74% improvement in compression per image, with an average of 41% savings per image. The data itself is a deduplicated set of hundreds of millions of image requests across several test customers. The one piece of data we should also report is the aggregate total savings per customer across all of their image requests. I will look into calculating that data point.

- Chris