You design a logo, send it to a printer, and it comes back blurry and pixelated on the banner. Or you try to edit a photograph in a drawing program and nothing behaves the way you expect. Both problems come from the same source: not understanding the difference between vector and raster graphics.
This is one of the first concepts any designer needs to internalise, and it is far simpler than it sounds.
Raster Graphics: Images Made of Pixels
A raster image is a grid of tiny coloured squares called pixels. Every photograph you have ever taken is a raster image. The computer stores a colour value for each pixel, and together those millions of dots form the picture.
Because the number of pixels is fixed when the image is created, enlarging a raster image cannot add detail that was never captured. The software simply makes each pixel bigger or invents intermediate ones by guessing, which is why zoomed-in images look soft or blocky.
This is what resolution measures. An image described as 1920 × 1080 has that many pixels across and down. For print, the relevant figure is pixels per inch (PPI) — the more pixels packed into each physical inch, the sharper the printed result.
Vector Graphics: Images Made of Maths
A vector image contains no pixels at all. Instead, it stores mathematical descriptions of shapes: this line runs from this point to that point, this curve bends with these control handles, this shape is filled with this colour.
When you scale a vector image, the software simply recalculates those shapes at the new size. A circle stays perfectly smooth whether it is printed on a business card or on the side of a building. There is no resolution, because there is nothing fixed to lose.
The trade-off is that vectors cannot easily represent the subtle, continuous tonal variation of a photograph. Vector art tends toward clean shapes, flat colours and defined edges.
Side-by-Side Comparison
| Raster | Vector | |
|---|---|---|
| Built from | A grid of pixels | Mathematical paths and shapes |
| Scaling | Loses quality when enlarged | Infinitely scalable |
| Best for | Photographs, detailed textures, painted artwork | Logos, icons, typography, illustrations |
| File size | Grows with dimensions and colour depth | Depends on shape complexity, usually smaller |
| Common formats | JPG, PNG, GIF, TIFF, WebP, PSD | SVG, AI, EPS, PDF (when vector-based) |
| Typical software | Photoshop, GIMP, Krita, Affinity Photo | Illustrator, Inkscape, CorelDRAW, Affinity Designer |
Choosing the Right One
The decision is usually straightforward once you ask two questions: does the artwork need to work at many different sizes, and does it contain photographic detail?
- Logos and brand marks: always vector. A logo will end up on a favicon and on a vehicle wrap, and one file must serve both.
- Icons and interface elements: vector, usually delivered as SVG so they stay crisp on any screen density.
- Photographs and photo composites: raster, with no realistic alternative.
- Digital painting and textured illustration: raster, where brush behaviour and blending matter.
- Print layouts: a mix — vector for type and graphics, raster for photographs, assembled in layout software.
- Signage and large-format print: vector wherever possible, because viewing distance does not forgive pixelation as much as people expect.
Converting Between the Two
Going from vector to raster is easy and lossless in practice. This is called rasterising: you choose an output size and the software renders the shapes into pixels. Every time a vector logo appears on a screen, it is being rasterised on the fly.
The reverse is much harder. Tracing a raster image into vector shapes — sometimes called auto-trace or image trace — works reasonably well for simple, high-contrast artwork like a black-and-white logo. For photographs or detailed images, the result is usually a mess of thousands of awkward shapes that is worse than the original.
The practical lesson is to create in vector whenever the artwork might need to scale, and to keep the original vector file. Recreating a lost logo from a low-resolution PNG is a genuinely painful job.
A Note on File Formats
Format names cause a lot of confusion, so a few clarifications help:
- PDF can be either. A PDF exported from vector software keeps the vector data; a scanned document saved as PDF is just a raster image in a PDF wrapper.
- SVG is text. An SVG file can be opened in a text editor, which is why it works so well on the web and can be styled with CSS.
- PNG supports transparency; JPG does not. This is the most common reason a logo appears with an unwanted white box behind it.
- JPG is lossy. Every save discards a little information, so repeatedly editing and resaving a JPG degrades it.
Practical Habits
A few working habits prevent most problems. Always keep the editable source file — the AI, SVG or PSD — separately from the exported deliverables. When a client asks for a logo, deliver a small package: a vector master, a transparent PNG at a generous size, and a JPG for contexts that need it.
When starting a raster project, set the dimensions and resolution correctly at the beginning rather than trying to scale up later. And when a printer asks whether your file is vector, they are usually asking whether it will hold up at the size they intend to print.
Conclusion
Vector and raster are not competitors — they are two tools with different strengths. Vectors describe shapes mathematically and scale perfectly, making them ideal for logos, icons and illustration. Rasters store pixels and capture photographic detail that vectors cannot. Knowing which one a job calls for saves rework and avoids the blurry-banner problem entirely.
If you want to build these skills properly, Cursa offers free courses in graphic design and digital illustration that cover both vector and raster workflows from the ground up.
