Rasterize vector objects but not text
I have been assigned the task of making one of our books available as PDF. Every page of it is made in illustrator and contains lots of text and vector graphics. The PDF I have is 57 MB which is too big for an e-book. I believe that rasterizing all vector graphics would decrease file size but all options of automatic rasterization that I have found entails also rasterizing the text, which I can't do. Is there any script or automated way of rasterizing all vector elements except for text in a PDF file? I have searched but been unable to find this.
I have already tried the save as reduced size PDF and optimized PDF but that doesn't reduce file size unfortunately.
