Art Exhibition Press Pack

I work for an art gallery, where we have to make press packs pdfs for each of our exhibitions and are struggling preserving the image quality of artwork images included in our press pack pdfs. I have attached an example of our most recent press packs. Have attached an example of our press packs (if you zoom, you will see the images are blurred) and a second press pack made by another gallery (if you zoom, the images remain clear). We need the press pack to remain under 20 MB. If you are able to help us find a solution, please reach out!