If you have a PDF with a dark background and you want to print it in black and white, there are several adjustments you can make to ensure optimal printing. One option is to use the built-in accessibility features in Adobe Acrobat or Reader. To do this, go to Edit > Preferences and select Accessibility from the Categories menu. Check the box next to Replace Document Colors and set the Page Background to white. This will remove the dark background and allow the text to be printed in black. Note that this may not work for all PDFs, as some files are designed to retain their background colors when printed.
Another option is to adjust the print settings in Acrobat or Reader. To do this, go to File > Print and select Print Color As Black from the dropdown menu. This will print all colors as solid black, rather than in shades of gray. If the checkbox is dimmed, click the Advanced button and make sure that Acrobat Default is selected in the Settings menu of the Advanced Print Setup dialog box. You can also try using third-party tools to extract the text from the PDF and make it darker, or convert the PDF to a different file format such as Word or PowerPoint, which may be easier to print in black and white.
Alternatively, you can try using Ghostscript's pdf2ps converter or a fake PS printer driver to get a PostScript file, then edit the file by putting 1 exch sub settransfer as the first line in the file and printing that PostScript file. This will invert the colors in the PDF, so that the background is white and the text is black. Finally, you can use the color adjustment settings on your printer to brighten the colors in the PDF, making them easier to see when printed in black and white. However, not all printers have these options, so this may not be possible for everyone.
Overall, there are several ways to adjust a PDF with a dark background for optimal black and white printing. The best approach will depend on the specific PDF and your printing needs. By experimenting with different options, you should be able to find a solution that works for you.