Rasters (images)

A raster is an image: colour stored on a fixed grid of pixels, rather than worked out by a formula.

A raster is a field, sampled onto a grid

If you've met Fields, a raster will feel familiar. A field is a formula DNA can ask for a colour at any point in space — infinitely sharp, no matter how far you zoom. A raster takes that idea and samples it onto a grid of pixels: so many wide by so many tall, each cell holding one colour.

That grid has a fixed resolution — that's all the detail it holds at any one moment. But "sampled onto a grid" does not mean frozen. The grid can be refreshed every single frame: a photo or logo you drag in is a still raster, while a webcam, a video, a rendered frame, or a feedback loop are rasters that change continuously. A raster is an image — it just doesn't have to be a static one.

Finite detail

Because a raster only stores a fixed number of pixels, it has limits a formula-based field doesn't:

If something can stay procedural (a shape, a noise pattern, a field), keep it procedural for as long as you can. Procedural things stay razor-sharp at any size. Turn it into a raster only when you actually need pixels — for export, for a paint effect, or to hand off to something that wants an image.

Fields turn into rasters automatically

You rarely have to think about the boundary between a formula and a grid of pixels — DNA crosses it for you.

When a procedural field needs to become an image (for example, to display it, paint into it, or feed it somewhere that expects pixels), DNA quietly bakes it: it evaluates the formula across a grid and saves the result as a raster. From that point on it behaves like any other image, with the finite-detail trade-offs above.

It also works the other way. Drop an image onto an input that wants a colour field and DNA wraps it as a field that samples the picture — so you can plug a photo into anything that fills with colour, like a shape fill or a scatter, with no manual conversion step.

A raster carries where it sits in the scene (its position and size), so when DNA samples it as a field it knows which part of space each pixel covers. Move or scale the raster and its sampled colours follow.

Rasters that keep a 3D look (impostors)

A raster doesn't have to lie flat on the canvas. DNA can capture content into a raster and keep showing it in the right place in your 3D scene, re-baking it as things change — an impostor. It stays a raster (cheap, flat pixels) but reads as 3D, because the image is continuously refreshed from the live view. That's how you get the look of heavy 3D for the cost of an image.

Don't confuse impostors with sprites. An impostor stays a raster. A sprite is a point that carries a raster as its texture — the thing on the wire is points, not an image. Both are made with the Rasterize node; see Sprites, impostors & billboards.

How a raster is sampled

When DNA reads a colour between pixels, two settings decide what you get:

Sequences of rasters

A single raster is one still image. A Frame Sequence is a stack of them — frames of a video, a flipbook animation, or captured output over time. DNA can show the newest frame live, scrub to a specific frame, or hand each copy in an iterator its own frame for per-instance variety.

See also