Scanned a Pdf with Washed Out Colors

Question

I scanned a book into a pdf, but the room light I used to illuminate the pages caused the scans to have a washed out effect

The black text at the top of the page is light in the scans. The lack of contrast makes it hard to read. The scans include color.

With the Adobe 2024 Creative Cloud tools (photoshop, illustrator, etc), is there a way for me to fix the washed out effect without ruining the parts that scanned well? Please note I am a beginner.

I tried using photoshop, but importing and exporting the multi-page pdf document was an issue. Also, some of the options suggested in tutorials were not available in my "save as" type windows on Mac.

I didn't see any relevant options available in Acrobat.

In Illustrator I tried adjusting colors, but it was also darkening my background. I tried rasterizing, but this made the text hard to read and I think I lost the page separations..

Is there a step-by-step process to fix my scans - make the dark text darker, not affect the colors, and maintain a multi-page pdf document?

Answer 1

(A comment only. It's written as an answer because I don't have the add comment button.)

The case is interesting - how to use room light in a scanner? In old days people tried to use low cost hand scanners which resembled this window cleaning tool:

The results were not perfect due non-uniform light and shaky scan movement. If you have a flatbed scanner try to redo the scanning job in a place where no external light can leak to the scanner. It's far easier than editing bad images. Have a lamp which is easy to turn off before pressing "scan".

The PDF is probably a container for one or more big raster images per page. In theory there could also be a hidden recognized text layer, but I doubt it. Any image contrast edit needs Photoshop, GIMP or other complex raster image editor. The images can be compressed in a modern way (say JBIG2 or something else) which can be complex to disassemble for edits (very tricky vector masks). A modern version of Photoshop may be able to open the pages. Or not. Do a search for JBIG2 in Google and also here in GDSE to find more.

Some old GDSE questions discuss the same problem. I mean non-uniform light and sometimes also curved edges. Generally they are tricky or even hopeless cases, because many people can figure out easy fixes by themselves.

You should include a short sample PDF to reveal how bad your case is. I'm afraid rescanning will be the fastest way. In some cases a scanner cannot be used at all because the book cannot be opened straight enough. Taking photos is the only way. The photos can be combined to a PDF afterwards.

To do the photographing job people have built or purchased special equipment to keep the book in a partially open position but with flat pages. They have assembled lights so that there's gloss free uniform lighting. Some use 2 cameras to double the speed. You find such guidance easily.