Please note that since this one is undated it probably won't be public domained without review by the Old Heads, so please, keep it in this group.
For most of my work the high-res is "normalized" to a "right reading" black-line on white 16-bit TIFF, so 1/3 smaller file size than color. But on this one color was a feature, not a bug. Because Lightroom (at least the archaic version I own) can't produce non-RGB files they are bounced to Photoshop for that final step. Call me lazy, but clicking a compression scheme is an extra step, so they are uncompressed, mostly.