I imported an external PDF with a white background and black font into my InDesign-document (still CS6). Is there a possibility to change the white color of the background into another color (such that it matches the surrounding area)? If yes, how?
- place the PDF as usually
- draw a colored rectangle or other shape over the placed PDF. Select the shape.
- goto Object > Effects > Transparency
- select blending mode = darken.
See an example:
This works only for black on white. You must separate colored images, but that can be done in Photoshop. As written in the comments for earlier answers, your PDF is a scanned one, so actually it's a photo.
It would be useful to have few more details. Have the elements been preserved as vectors inside the PDF or are the pages flattened?
If your case is the first one, I recommend creating a master page with the background that you would like to apply, apply it to the pages, and then delete the existing white background from the pages of the document.
When creating the master, make sure to place the new background in a new layer sitting under the elements.