Inserting Images into Excel

JPEG is a high-compression format; the flip side is, it's notorious for lossy images, especially when you're trying to represent text.

(TIF and PNG are newer formats with less artifaction, so they tend to look better.)

PDF... by design, they're relatively small files, which exactly means you have fewer pixels for any image.

Excel doesn't know what TIF or PNG are so it's probably just forcing those images into the JPEG format. (Well, probably a bitmap, actually).

Personally, I would avoid this daisy-chain of word => pdf => image => excel, because each of those formats has different priorities (text vs picture), so what you're doing is stacking all of their "throw out the low priority data to save space" on top of each other and ruining your image quality.

Microsoft already has a straight-forward way to embed Word in Excel that will allow you to avoid that whole mess. Especially if you have the .doc file to work with.