Brightening a pdf

I often check books out of the Internet Archive library, and find that some of the earlier scans are quite dark. If it turns out that we have a dark scan of a pdf, we can lighten it to better read it using Adobe Acrobat.

However, the process to do that depends on the version of Acrobat that we have.

If we have Adobe Acrobat IX we can change some settings and rescan the file. Simply go Edit | Preferences | Accessibility | Replace Document Colours and ensure that Custom Colour is ticked along with background colour set to white and document text set to black. Tick the option, "Change the colour of line art as well as text".

If we have Acrobat XI, select Tools | Document Processing | Optimize Scanned pdf. When the dialogue box opens, click on the Edit button in the Filters section and turn "Background Removal" on. Adjust the other filters as desired.

Both will work.


Sam

References:

• Goodwin, A. (2 December 2016). How do I adjust contrast of a PDF in Adobe Acrobat Pro 9? Retrieved from https://www.quora.com/How-do-I-adjust-contrast-of-a-PDF-in-Adobe-Acrobat-Pro-9
• Lymburner, M. & Kremer, K. H. (n.d.). brighten a PDF page. Archival PDFs are black with a light grey background. PhotoShop works but tedious process. Retrieved from https://answers.acrobatusers.com/brighten-a-PDF-page-Archival-PDFs-are-black-with-a-light-grey-background-PhotoShop-works-but-tedious-process-q119143.aspx