EXIF resolution information not applied

• Component: Images
• Status: NEW ---

[Eric Portis]

https://cdpn.io/eeeps/debug/LYyRVOR

The third image on this page should have an intrinsic size of 1920 x 1280, from its EXIF information. Instead, it has an intrinsic size of 864 x 576.

It displays as expected in both Chrome 91 and Firefox 90. Safari passes the relevant Web Platform Tests (https://wpt.fyi/results/density-size-correction?label=master&label=stable&aligned), so there must be an issue with this particular image.

Tested on:
Safari Version 14.1 (16611.1.21.161.3)
Safari Technology Preview Release 127 (Safari 15.0, WebKit 16612.1.18.11.3)
macOS Big Sur 11.3 (20E232)

[Simon Fraser (smfr)]

Firefox and Safari match for me. Chrome shows the image larger.

The image EXIF has a DPI of 32.4 pixels per inch.

[Eric Portis]

@smfr:

Make sure you test in Firefox 90, which is fairly new and also the first version to ship support for EXIF-based intrinsic sizing. In v90, the third image appears large (as expected), for me.

Re: the DPI, a couple of notes...

- Binary EXIF stores `XResolution` and `YResolution` as rationals, hence 162/5 in the exiftool code. (A happy side effect of this is perfect precision.) exiftool prints decimals when it reports, though.
- The default values, according to the EXIF spec, are 72 dpi, so 32.4 is equivalent to 0.45x/ddpx, in terms of HTML/CSS.

[Eric Portis]

s/ddpx/dppx

[Radar WebKit Bug Importer]

<rdar://problem/80881733>