PDF to Image Quality: How to Get Sharp Text Every Time

Last month a user sent me a screenshot of a PDF they'd converted to an image. The text looked like it had been smeared with vaseline. "Your tool is broken," they said.

It wasn't broken. They'd converted a text-heavy PDF to JPEG at 72 DPI. Every one of those choices was wrong for their use case. Here's why, and what to do instead.

The #1 Mistake: Using JPEG for Text Documents

JPEG compression was designed for photographs — smooth gradients, natural textures, organic shapes. It achieves small file sizes by blurring away fine detail that your eye won't miss in a photo.

Text is the opposite of that. Text is sharp edges, high contrast, fine detail. JPEG compression turns crisp letter edges into smudgy halos. The technical term is "ringing artifacts" and they look terrible on text.

For any PDF that contains text, use PNG. Yes, the file will be larger. A text-heavy A4 page at 300 DPI as PNG is about 800KB-1.2MB, versus 150-250KB as JPEG. But the text will be sharp and readable. That's the whole point.

DPI: The Setting That Changes Everything

When you convert a PDF to an image, you're taking a vector document (infinitely scalable) and rasterizing it into a fixed grid of pixels. The DPI setting determines how fine that grid is.

At 72 DPI, a standard A4 page becomes a 595x842 pixel image. That's barely readable on a phone screen.

At 150 DPI, it's 1240x1754 pixels. Readable on screen, but text looks soft if you zoom in.

At 300 DPI, it's 2480x3508 pixels. Sharp text, print-quality. This is what you want for almost everything.

I ran a readability test — printed out PDF-to-image conversions at different DPIs and asked five people to rate text clarity on a 1-5 scale:

The jump from 72 to 150 is dramatic. From 150 to 300, it's more subtle but still noticeable, especially on small text and tables.

When JPEG Is Actually Fine

If your PDF is mostly photos — a portfolio, a lookbook, a photography zine — JPEG at quality 85-90 is perfectly fine and much smaller than PNG. The rule is simple: text-heavy = PNG, photo-heavy = JPEG.

And if you need the smallest possible file size and your audience is on the web, WebP at quality 90 gives you sharp text at roughly 60% of the PNG file size. I added WebP output to our PDF converter for exactly this reason.

Multi-Page PDFs: Batch Convert the Smart Way

For long PDFs, converting every page individually is tedious. Our tool lets you convert all pages at once and downloads them as a ZIP file. One thing I'd suggest: if your PDF has both text pages and photo pages (like a product catalog), convert everything to PNG. Trying to optimize format per page isn't worth the hassle unless you're dealing with hundreds of documents.

The Reverse Direction

Going image to PDF is much simpler. Combine multiple images into one PDF, set the page size, done. The main thing to watch for is image orientation — phone photos often have rotation encoded in EXIF metadata rather than in the actual pixel data, which can cause them to appear sideways in PDFs. Our image to PDF tool handles this automatically, but it's a gotcha if you're doing it programmatically.