At 100% the photo's corner could sit half a physical pixel off, for
example in a 1279.5 pt canvas on a 2x display. The GPU then resampled
the photo with its bilinear filter and blurred it. On a 5152x7728 JPEG
the 100% view kept 68% of the fine detail.
fit_rect now rounds the corner to a whole physical pixel when the photo
is 1:1 with the screen. Other zooms resample anyway, and a pinch must
not jump, so they stay as they were. With the fix the same view matches
the original (71.4 dB PSNR, 100% of the detail).
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>