flatten images with transparency in PDF

Question

How to flatten images in PDF files with transparency?

convert PDF to PS (postscript)

pdftops input.pdf output.pdf.ps

If a PDF file contains eg. PNG files with alpha channel (transparency) the PDF is rendered/rasterized to an image and that is not a solution because then you lose the plain text in the file

Is there a tool (linux command line) to flatten images in PDF files with transparency?

Answer 1

Its not clear why you want to do this. If you want PostScript then Ghostscript can produce PostScript for you from a PDF file (use the ps2write device). Obviously transparency will have to be rendered to an image, in which case the resolution is important. The default is 720 dpi which is probably higher than you might need.

Note that a PDF file can't contain a PNG, that's not a possible image type in PDF. A PNG would have to be stored as an image with a separate alpha.