reNightDuotone low-vision rendering optionproperty NightDuotonePaper: TColor;
When reNightDuotone is present in Options, TPdfView maps the rendered page luminance onto NightDuotoneInk and NightDuotonePaper before overlays are painted
Assigning this property invalidates the view at once when reNightDuotone is active
clBlackPdfView1.NightDuotonePaper := clBlack;
PdfView1.Options := PdfView1.Options + [reNightDuotone];