Images
What is Raster image?
Also called raster graphics or bitmap image.
A raster image is a picture made from a fixed grid of pixels. Photos, screenshots and scans are raster images, as are JPEG, PNG and WebP files.
How it works
A raster image stores color values for every position in a rectangular grid. That suits anything captured from the real world, where each point can differ from its neighbors: photographs, scans and screen captures.
Its detail is fixed when it is created. Shrinking a raster image discards pixels; enlarging it makes software invent new ones, which softens edges. File size grows with pixel count, so large raster images need compression.
Raster vs vector
| Feature | Raster | Vector |
|---|---|---|
| Made of | Pixels | Shapes and paths |
| Scaling up | Gets blurry | Stays sharp |
| Best for | Photos, scans | Logos, icons, diagrams |
| Formats | JPEG, PNG, WebP, GIF | SVG, EPS, PDF drawings |
Most real documents mix both: a PDF can hold vector text beside raster photos.
A practical example
Converting a PDF page to JPG turns crisp vector text into a raster image. Zoom in far enough and the letters become visibly square-edged.
What to watch out for
Raster images lose sharpness when enlarged beyond their pixel dimensions. Keep logos and diagrams in a vector format for as long as possible and rasterize only the size you need.
Tools you can use
- Image Resizer · Scale to a size, a percentage or a platform preset
- PDF to JPG · Every page as an image, at the DPI you need
- PDF to PNG · Lossless page images, crisp text
- Extract Images From PDF · The original image files, not screenshots
- Image to PDF · Turn photos and scans into one document
Go a little deeper
- How to convert a PDF to JPG on a phone
- How to get images out of a PDF
- How to make a PDF from photos on an iPhone
- How to make an image 300 DPI
Common questions
Is a PNG a raster or vector file?
Raster. PNG, JPEG, GIF, WebP, AVIF, HEIC and BMP all store pixels. SVG, EPS and most PDF text and drawings are vector.
Can I convert a raster image to vector?
Only by tracing, where software draws shapes that approximate the image. It works for simple logos with flat colors and poorly for photos.
What does rasterize mean?
Converting vector shapes or text into pixels at a chosen size. It happens every time a vector drawing is displayed on screen or exported as PNG or JPEG.