Pagespeed Resizes Landscape Images Incorrectly: Using Height of Original Image as Width for Resized Image

[Fred Onis]

Actual:

• Pagespeed Insights resizes landscape images when the CSS-resized dimensions are smaller than the actual dimensions.
• Pagespeed Insights incorrectly uses the CSS-resized height as the new width.

Expected:

• Pagespeed Insights should use the CSS-resized width as the new width.
  

Steps to repeat:

1. Navigate to https://developers.google.com/speed/pagespeed/insights/
   
2. Enter [https://neckermann.nl/stedentrips.aspx]
   
3. Click button [Analyze]
4. Click tab [Desktop]
5. Click link _Download optimized image, JavaScript, and CSS resources for this page_
   
6. Save to disk, unzip and open its image folder to view the downloaded files
7. Observe the Pagespeed-resized dimensions of file vind-stad-die.png: width is 245px, height is 126px
8. Navigate to https://neckermann.nl/stedentrips.aspx
9. Inspect the bottom-most photo with filename vind-stad-die.ashx
10. Observe the CSS-resized dimensions of file vind-stad-die.jpg: width is 477.5px, height is 244.73px
11. Download the bottom-most photo with filename vind-stad-die.ashx
12. Rename it to vind-stad-die.jpg
13. Observe the actual dimensions of file vind-stad-die.jpg: width is 956px, height is 490px

The same behaviour can be seen for the six banners below the heading "Populaire filters" as well as for the "Gratis nachten" photo next to th esearch panel.