Raster vs Vector: Pixels or Instructions
Every image on your screen is one of two things underneath: a photograph-like grid of dots, or a set of shapes described by coordinates and curves. The difference decides whether zooming in reveals detail or reveals blur.
Definition
Raster (bitmap) graphics represent an image as a fixed grid of pixels, each with a color value. Vector graphics describe an image as geometric primitives, points, lines, curves, and fills, that render cleanly at any resolution.
Why it matters
If you're converting a logo for a billboard, a raster PNG will pixelate; a vector SVG or PDF will stay crisp. Conversely, a photograph has no meaningful vector form, trying to convert it to SVG produces a huge, blotchy trace, not a magical upgrade.
Advantages
- Vectors scale from favicon to billboard with zero quality loss
- Rasters capture photographic detail vectors simply can't describe
- Vector files are usually tiny for logos, icons, and diagrams
- Recognizing which one you have prevents doomed conversions and blurry exports
- Vectors are editable shape-by-shape; rasters force pixel-level retouching
Disadvantages
- Rasters lose quality when scaled up past their native resolution
- Vectors struggle with photorealism and gradients-heavy artwork
- Vector rendering can be slow for very complex illustrations
- Not every app or platform accepts SVG/EPS/PDF for upload
- Auto-tracing raster to vector rarely produces production-quality output
Examples
- A brand logo delivered as SVG for the web and PDF for print
- A phone photo in JPEG, raster, and no realistic vector equivalent
- An icon set in SVG so it renders sharp on retina displays
- A scanned document, raster, even though it contains text
- A CAD drawing exported as PDF, staying precise at any zoom
Common misconceptions
- 'PDF is a vector format'. PDFs can hold either, or both
- 'High-DPI raster equals vector', it just delays the pixelation
- 'SVG works for photos', technically yes, practically no
- 'Converting JPG to SVG makes it scalable', it makes it a traced approximation
- 'Vector files are always smaller', a complex illustration can be huge
Frequently asked questions
You can trace it, but you'll lose photographic detail and end up with flat color regions. For photos, stick with raster formats.
Vector. A logo needs to work at every size from favicon to signage, and only vector guarantees crisp edges across that range.
Both are possible. A PDF exported from Illustrator is vector; a scanned PDF is raster pages wrapped in PDF.
They're almost certainly raster (PNG or JPG). Request or export a vector version (SVG, PDF, EPS) from the source file.