When exporting PDFs to JPG/PNG, or compiling images into a single PDF, you might notice that text sometimes becomes blurry. This is caused by the fundamental differences between Vector graphics (used inside PDFs) and Raster graphics (used for standard images).
What is Raster (Bitmap) Graphics?
Formats like JPG, PNG, WebP, and GIF are raster images. They represent graphics using a grid of colored pixels. While excellent for displaying rich photographs, scaling them beyond their original resolution stretches the pixels, causing jagged edges and blurry details.
What is Vector Graphics?
Vectors use mathematical formulas (points, lines, paths) to render shapes dynamically. Because it calculates geometries on the fly, vector graphics remain perfectly sharp at any zoom level. Fonts, PDF text layers, and SVG files are all vector-based.
Smart Conversion Tips
Knowing these concepts helps you achieve high-quality conversions:
- PDF to Image: Since vector text must be rasterized into pixels, resolution (DPI) is critical. Use at least 150 DPI for screen viewing and 300 DPI for print to keep text readable.
- Image to PDF: Packaging existing raster images into a PDF does not automatically increase their quality. It simply packages those pixels into a single, easily shareable file container without altering the underlying image data.