Image natural dimensions strict to the precision of 4th decimal place

Hello, I noticed a “best practices” issue while testing some image srcsets. Here’s a similar issue from 2018 (#5356) where the ratio check was loosened.

What is the current behavior?

At first, it looked like an image size issue, but using object-fit: cover; fixed it. So I checked the ratio and found that there are small differences between what’s being displayed and the natural dimensions of the image.

1st image displayed and expected vs displayed ratio is: 0.9473 (360x380, 1080x1140) vs 0.9478 (800x844) 2nd image displayed and expected vs displayed ratio is: 1.2631 (360x285, 1080x855) vs 1.2618 (800x634)

What is the expected behavior?

Unless I’m misunderstanding the “natural dimensions” audit, a check which is a little bit less strict.

Environment Information

• Affected Channels: DevTools
• Lighthouse version: 6.0.0
• Chrome version: Version 85.0.4183.121 (Official Build) (64-bit)
• Node.js version:
• Operating System: macOS Catalina

[patrickhulce]

I’m going to let this issue track updating quantizeDPR to never use anything more than 2 and the expectations accordingly, which should also fix the DevTools problem you’re seeing.

[zenofewords]

Thank you for the quick feedback!