Nice, but I’m not sure how practical that would be.
Gigapixel does not give any indication of expected export file size, and there is possibly a good reason for that.
While it is relatively easy to calculate an approximate file size for a non compressed image file, arriving at one for a compressed image file is a whole different ball game.
The size of a compressed image file depends on a number of things,including
(a) which format is used (JPG, TIFF with LZW compression, TIFF with ZIP compression etc)
(b) Any “quality” setting made (For example with Gigapixel JPG exports, the Image quality setting chosen)
© the content of the actual image itself (identical pixel size images can compress differently)
The only way I’m aware of to get an accurate file size indication prior to writing the file, is to effectively have the software do all of the processing, except for the actual file write itself.
Now to have it work backwards, to resize an image such that a specified file size is obtained would I believe require some form of iteration, and might be unacceptably slow.
But maybe Topaz can come up with a clever way to make it practical.