They are not searchable because they do not contain text to search. Typically, they contain image only.
The way I deal with it - I OCR the image, generate text document and place that text into a layer under the image in the output PDF. Having the text under the image layer preserves the original look of the pdf why allowing for search and select. I have seen pdf with text over the image, obscuring it - as well as various attempts of making the text over the image invisible. Of course, OCR is not perfect as well as preserving the text in the exact position under the image. It mostly works for text, not so much for data extraction from tables, etc. I do not believe that there is OK-ish free SW solution to this. I use commercial SW to do that. It works, but I cannot publicly recommend it due to their nasty commercial behavior - no respect for privacy no sale just licensing with build in obsolescence. Tomas On Fri, Jul 23, 2021, 16:18 Rich Shepard <rshep...@appl-ecosys.com> wrote: > I've encountered a few PDF-1.5 docs that are not searchable using xpdf, > mupdf, okular, or MasterPDFEditor. Perhaps they're scanned and I don't know > how to determine if they are. > > My web searches found nothing relevant; my search terms might be > inefficient. > > Has anyone else experienced this? > > Rich > > >