I don't seem to get HiDPI images working in Tiger (tried Photoblogger as well, same). I have checked the option for HiDPI images in the Pages tab and provide images that are at least twice the resolution of the image size for the Lightbox (Lightbox: 1080x1080, images: >2160x2160). The Lightbox always shows the image at its "native" resolution (2160x2160). I have also selected "Link to scaled-down images only" in the pages tab. See my settings in attached screenshots.
(this on a local test-server, the published site is still using non-HiDPI until I get it to work).
Yes, I'm seeing the same thing. Even selecting Scaling: Original (1:1) size and Never scale up, the lightbox images are still being shown larger than the chosen image bounds. De-selecting HiDPI images restores the expected lightbox behavior.
You don't need a high-density display to test this. Set the image bounds to 1000x800, HiDPI, and tell Tiger Never scale up. The lightbox should never be more than 1000px wide. Period. Ever. But the lightbox ends up being wider than that on a large-ish monitor.
On a high-density monitor, what Tiger is doing is defeating the purpose of the HiDPI setting, by showing the image at normal density.
Leave the image bounds set at 1000x800 (the default), but choose HiDPI images. In the Tiger settings, choose Never scale up.
On my 1920x1080 monitor, the lightbox shows the image at 1268x869px. It should never, ever, be shown larger than 1000x800, the image bounds. Without HiDPI images chosen, it shows correctly at 1000x669px.