Dark basecolor export of materials

I am creating a material from an image of a megascans rock, then exporting Unity HD Standard material maps.  For some reasons, the basecolor map is much darker than the original image and is unsuble in unity for that reason.  The weird thing is that out of about 10 images, this is happening to 6 of them and the other 4 Re exporting with the normal color vibrance as the original.  What would make a basecolor/diffuse/albedo map export darker?  I tried numerous export settings of PNG, Targa and JPEG and every preset exports these dark basecolor images.  Any help would be greatly appreciated!  Thanks.