There is a need to invert colors in a PDF file and that is widely searched and requested on the web. Please don't refer me to the feature that already exist in accessibility tab. You well know that its immature and doesn't work with files with images and line arts. Also why there is inconsistency in your products? On android this feature exist but not on Windows. Is it really that hard that over the years we still don't have a proper color inversion?!!