Raster vs. vector images: the difference, and when to convert

Raster images: a grid of pixels

A raster image — also called a bitmap — is a grid of tiny squares called pixels, each a single color. A 1,000 × 1,000 image is a million of them. Photos from a camera or phone are raster, and so are screenshots, scans, and most images on the web. The common raster formats are JPG, PNG, WEBP, GIF, TIFF, and HEIC.

Raster is ideal for photographs, where color shifts subtly from one pixel to the next. Its weakness is that the pixels are fixed. Enlarge a raster image and each pixel just gets bigger, so edges turn soft or blocky — the familiar pixelated look.

Vector images: shapes described by numbers

A vector image stores shapes instead of pixels: a circle here, with this radius, filled orange; a curve from this point to that one, bending like so. Software draws the shapes at whatever size is needed, so a vector logo is as sharp on a business card as on a billboard — and the file is the same size either way.

Vectors are editable shape by shape: you can recolor one element, move it, reshape its outline, or delete it. The common vector formats are SVG, EPS, PDF, AI, and DXF.

Side by side

Which one do you need?

Use vector for:

• Logos and brand marks, which have to work at every size.
• Icons, illustrations, and charts on the web — SVG is small and stays crisp on high-density screens.
• Large-format print: signs, banners, vehicle wraps.
• Cutting, engraving, and plotting — the machines follow paths.
• Anything you’ll recolor or rearrange piece by piece.

Use raster for:

• Photographs and anything photographic.
• Textured or painterly artwork, where the texture is the point.
• Finished images for social media and web pages, where the display size is known.

How to tell which one you have

• Zoom right in. Blocky or blurry edges mean raster. Edges that stay perfectly sharp at 1,000% mean vector.
• Check the extension — but don’t trust it. A PDF, EPS, or SVG can have a raster image embedded inside it. A “vector” file that’s a photo wrapped in a PDF is still a photo.
• Open it in a vector editor such as Illustrator, Inkscape, or Affinity Designer and try to select parts of it. Separate shapes with anchor points mean vector; one rectangle you can’t pick apart means an embedded raster.
• For an SVG, look at the code. Open it in a text editor: <path> and <circle> elements are vector; an <image> element holding base64 data is a raster in disguise.

Converting raster to vector

Going from vector to raster is trivial — every editor can export a PNG. Going the other way means rebuilding shapes from pixels, and that’s what image tracing does: it groups pixels into regions of flat color and fits smooth outlines around them.

Renaming a file, or choosing “save as SVG” in a raster editor, does not do this. At best it wraps the pixels in a vector container: a file with the right extension and none of the benefits.

Tracing works best on images that are already vector-like: logos, icons, flat illustrations, line art, lettering. It works on photos too, but the result is a stylised illustration rather than a copy — see turning a photo into vector art. To try it, follow the step-by-step guide or just drop an image in.

Common questions

Is PNG a vector format?

No. PNG is raster. It supports transparency, which is why logos are often shared as PNGs, but it’s still pixels.

Is a PDF vector or raster?

Either, or both. PDF is a container that can hold vector shapes, text, and raster images. Whether a PDF logo is vector depends on what was put inside it.

Is an SVG always vector?

The format is, but an SVG can embed a raster image. Look for <image> elements. What is an SVG file? explains what a real one contains.

Does converting to vector make an image higher resolution?

It makes a file that scales without blurring, built from the shapes the tracer found. Fine detail and texture are simplified along the way. For logos and flat artwork that’s an upgrade; for photos it’s a change of style.