Since Gigapixel AI can’t be used as an external editor in Lightroom (the image doesn’t get passed), my desired workflow is this: Export the image as unresized .TIFF to “Same folder as original photo” and with “_GIGAPIXEL” appended to the filename. Use the option to Add to catalog. In the Post-processing panel of the Export dialog, choose Gigapixel AI. Gigapixel AI would then use this exported version for processing. If the output could be specified to overwrite the source file (with or without a warning dialog), I would then have the Gigapixel-processed image in my Lightroom catalog alongside the LR-processed image without the need to import or Synchronize Folder after Gigapixel AI processing. Currently, the output file is renamed as “…GIGAPIXEL (1).TIFF”
The same workflow would be desirable for Sharpen AI or any product that Lightroom can’t pass an image to. I suppose I can use Topaz Studio as an external editor and call Gigapixel AI or Sharpen AI from there, but often the enlargement or Sharpen AI is the only edit I need or want.