When to Convert PDF to Image Instead of Keeping the PDF
Sometimes a picture of the page is what you need
You want to drop a page into a slide deck. You need to post it on social media. You are making a design mockup. In all these cases, an image is the format everything else expects.
What you lose when you convert
Text stops being selectable. Links stop working. Form fields become part of the image. If someone needs to copy text from the page, PDF to Text or PDF to Word would serve better.
PNG or JPG for your pages
PNG is lossless — it keeps every pixel exactly as rendered. Better for text, diagrams, and anything with fine lines. JPG compresses more aggressively, which can blur small text but makes smaller files.
If you only need one page from a long PDF, extract that page first using a PDF splitter, then convert just that page.