How to straighten waved (not curvy) image with Photoshop or similar program

If this is scanned text and you don't need it to look like scanned page do some magic in Adobe Acrobat. http://blogs.adobe.com/acrolaw/2013/06/straighten-and-deskew-pdf-pages-in-acrobat-xi/ From Tools select "Document processing". Click "Optimize Scanned PDF", Deselect “Apply Adaptive Compression” and from "Filters" options choose the one that you would like to apply (for example background removal).

Then you could try tools for creating panoramas as they look for straight line and fix photos together (some cutting out may be required)

And the easiest way for me (if the wave is in the same place) would be to use Displacement Map in Photoshop. Because that's what you want to do. Displace picture.