Raster Image
Overview
A raster image is an image made from a fixed grid of pixels, where each pixel stores color information at a specific position.
It matters because raster and vector graphics behave differently in editing, scaling, compression, and delivery workflows.
What Raster Means
Raster graphics are pixel-based rather than mathematically defined.
That makes them common for:
- photographs
- screenshots
- digital painting
- textures
- image-heavy web assets
This is why so many everyday image formats are raster-based.
Raster vs Vector
Raster is often compared with vector.
- Raster images are fixed-resolution pixel grids.
- vector graphics scale more cleanly for shapes and line-based art.
That difference matters because the wrong format choice can make assets blurry, heavy, or harder to maintain.
Why Raster Matters
Raster matters because most real-world visual content captured by cameras or screens is pixel-based.
Teams rely on raster images for:
- product screenshots
- marketing photography
- UI captures
- media assets
- exported artwork
That makes raster formats central to web and content workflows.
Practical Caveats
Raster images are useful, but they have tradeoffs.
- Scaling can reduce quality.
- File size can grow quickly.
- Transparency and compression behavior vary by format.
- Raster is often the wrong choice for simple icons or diagrams.
The right format depends on the kind of image and how it will be used.
Frequently Asked Questions
Is a raster image the same as a bitmap?
In many practical contexts, yes broadly, though terminology can vary by platform and workflow.
Are photographs usually raster images?
Yes. Most digital photographs are stored as raster data.
Is raster worse than vector?
No. They solve different problems.
Resources
- Adobe: Raster vs. Vector
- MDN: Image File Type and Format Guide
- Library of Congress: Still Image Formats