Smart Preview limitations

[JWB]

Can anyone tell me what the limitations are of smart previews? I understand that they're lower resolution and I assume already demosaiced, but at what bit depth are the images saved? Do we know what kind of compression is used? What about color profile?

[john beardsworth]

You can actually see this for yourself by going into the catalogue's smart preview folder and copying one file to your desktop. Change its name, import it into LR, and look at it in the Metadata panel. Here is the DNG view, but other metadata is copied directly from the original.

Limitations for what? What are you thinking of doing with them? Normally, they're just something that facilitates other tasks.

[JWB]

Thank you John, this was the kind of thing I was looking for. In particular, I see that the smart previews are 8-bit. I'm also curious about the color profile used. Is it sRGB? Is it Display P3 or AdobeRGB?

The reason I'm inquiring is that I would like to know what it is that I'm looking at, especially when trying to edit in Lightroom Mobile (files synced from Lightroom Classic CC). How accurate is the color. Is Lightroom Mobile taking advantage of my iPad Pro's wide gamut display? Is Lightroom throwing away all my highlight and shadow information?

I fear that smart previews are just glorified jpegs. Perhaps Adobe will eventually develop a smart preview 2.0 that supports 10-bit color, Display P3, and HEIF compression. Though I suppose we're a bit early on that. A first step, I guess, would be for Lightroom merely to let me export to HEIF.