Question PDFs of old books, pages' dark background

[Christian1]

(I hope this is the correct forum-section for my question)

Hi everyone

I wonder whether anyone could assist me, please

I was given a few PDFs of fairly old books.

The text is black (which is perfectly OK) but the pages are dark brown, which makes it difficult to read them.

Is there any way to change the colour of the pages into white?? Or anything that can make those PDFs easier to read??

in advance, thank you very much for your kind assistance

Christian

 

[mpo]

Check your scanning software to see if there is an option for removing the background color.

 

[Steltek]

This may or may not work depending upon how the PDFs were created, but in many cases it will at least get the file so you can read it. Also, please note that you aren't changing the file, but rather the Acrobat Reader preferences related to accessibility for those with disabilities. As a result, you may want to change the setting back once you are finished reading the PDF at issue because it might cause future issues with PDFs with background colors that you don't want to change.

In Acrobat Reader:

1) Click on the Edit menu, then go to the Preferences submenu
2) Under Categories, click on Accessibility
3) Check the box next to Replace Document Colors
4) Choose the Custom Color radio button
5) Pick a background color, and a text color you like
6) Click Ok.

Acrobat Pro (and maybe even Acrobat Standard, don't have it so I don't know for sure) does have a function to permanently change background colors and text colors. However, as stated above, it may not always work with existing PDF files due to the methods used to generate those PDF files. In my experience, the older the file the less likely it is to work due to the PDF standards that were weaker/less evolved with older files.

 

[mindless1]

If the pages are just a series of scanned images that weren't OCR'd (which I assume, or else it wouldn't have a poor contrast background), you may have to extract every page as an image and change the contrast or tweak the highlight/midtone/shadow values in order for OCR to work, but it may not be necessary, worth a try to OCR the PDF file as-is first.

There's probably some lower cost alternatives but AFAIK, Acrobat Pro can do the OCR.

If you end up extracting page images, some image viewing apps can allow reading each sequentially numbered file as the next page, otherwise they can be put back together into a PDF.

Another option might be to hunt down better scans or OCRs of the same books instead of working with what you have.