Improving quality of scan document

[erne.castro]

Hey all, this is my first post here, although I have used Gimp for a long time for simple things.

I have problem that I think Gimp could help me solved, but I'm not sure how. I have an old service manual scanned, in a very good shape in general, but would be great if I can bring it to almost perfection. I think there are three things that could improve the current quality from an 80% to a 95% (subjective numbers). These things are:

• Remove all single pixel marks. The document has in the background some single pixels (over the white background). Removing al those would be a large improvement.
  
• Straighten out the pages. Some pages are not perfectly "vertical", so detecting the pages that are at an angle and rotating them would also be a huge improvement.
  
• Use OCR to read the text and replace the some how "broken" characters with newly rendered ones of the same font and size.
  

I think the last one is the hardest one. Anyway, another challenge is that the document is 400+ page long, so whatever I do should be scripted, something like:

• PDF to individual images
  
• Process each image
  
• List of images to PDF
  

Does anyone have an idea on how I could tackle this? If instead of Gimp I should use another tool I'm also opened to suggestions.

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Attached is an example of a page.