Use raster images for photographs, screenshots, paintings, textures, and other artwork whose detail lives in individual pixels. Use vector images for logos, icons, diagrams, line art, and shapes that must remain crisp or editable at many sizes. Neither type is universally better.
Understanding the underlying content matters more than recognizing a filename. An SVG can contain a raster image, and a PDF can contain raster, vector, or both.
What is a raster image?
A raster image is a fixed grid of pixels. Every pixel records color and, in formats that support it, transparency. PNG, JPEG, WebP, AVIF, GIF, BMP, and TIFF are common raster formats, although their compression and feature sets differ.
The grid has a specific width and height. Reducing a raster image is usually straightforward, but enlarging it beyond its useful source resolution requires interpolation. Edges can become soft or visibly blocky because the file does not contain the original curve—only the pixels that represented it at one resolution.
Raster is a strength when individual color changes matter. A photograph can contain fine skin texture, foliage, reflections, and continuous tone without describing each detail as a separate object.
What is a vector image?
A vector image describes geometry: paths, curves, rectangles, circles, fills, strokes, transformations, and other drawing instructions. SVG and EPS are vector-oriented formats. AI files and many PDFs can also contain vector artwork.
A renderer calculates the pixels needed for the chosen display size. Clean paths therefore remain sharp on a phone, a high-density monitor, a sign, or another large surface.
Vector artwork can also be structurally editable. A designer may select one shape, change its fill, move a node, or resize the composition without painting individual pixels.
The practical differences
| Requirement | Raster | Vector |
|---|---|---|
| Photographic detail | Strong | Usually inefficient to trace |
| Scaling far beyond source size | Limited by pixels | Strong for genuine vector elements |
| Editing individual shapes | Pixel editing | Path and object editing |
| Transparent background | Supported by formats such as PNG | Supported through unpainted areas and opacity |
| Simple logo file size | May require large dimensions | Can be compact when geometry is simple |
| Complex image file size | Often efficient with the right format | Can become very large with many paths |
The file extension alone does not determine quality or size. A one-color icon may be much smaller as SVG than as a large PNG. A photograph traced into thousands of shapes can be larger and harder to render than an optimized raster image.
Choose by subject matter
Raster normally suits:
- photographs and product images;
- screenshots and interface captures;
- paintings and textured illustrations;
- soft shadows, blur, grain, and complex lighting; and
- final-size images accepted only by raster upload forms.
Vector normally suits:
- logos and brand symbols;
- interface icons;
- signatures and simple line drawings;
- diagrams, maps, and charts made from shapes;
- artwork sent at many sizes; and
- files that need editable curves or flat colors.
Many real projects keep both. A brand may store an approved SVG master and export specific PNG sizes for social platforms or office tools.
How to tell whether a file is genuinely vector
Open the file in a vector editor and try selecting individual shapes. Zoom in substantially. Genuine paths remain mathematically smooth, while an embedded bitmap eventually reveals pixels.
You can also inspect SVG markup. Path-based artwork contains elements describing geometry. An SVG that contains an image element with encoded PNG or JPEG data is an SVG container with raster content.
This is not inherently wrong. PNG2SVG’s Lossless mode creates that structure intentionally to preserve the PNG. True vector mode traces paths. The correct structure depends on whether fidelity or editable geometry is required.
Read Lossless SVG vs True Vector SVG for a direct comparison.
Why changing the extension is not vectorization
Renaming picture.png to picture.svg does not change the data. The file will remain PNG data with a misleading name and may fail to open.
Embedding a PNG inside SVG creates a valid SVG document, but it still does not reconstruct paths. True vectorization requires tracing or manual redrawing.
Automatic tracing estimates geometry from pixels. It cannot recover original layers, fonts, or exact control points. A clean simple source works better than a blurry or highly textured one.
Which type should you send to a printer?
Ask the printer. Vector artwork is often preferred for logos, line art, and lettering, while photographs remain high-resolution raster images. The provider may request PDF or EPS instead of SVG and may have specific color, bleed, font, and proofing requirements.
The SVG for print and branding guide explains the handoff in detail.
Which type should you use on a website?
Use SVG for simple logos, icons, and illustrations that benefit from responsive scaling. Use an appropriate raster format for photography and texture. Evaluate actual file size and rendering cost rather than assuming vector always loads faster.
Provide accessible text alternatives, size images responsively, and accept SVG only from trusted sources. See SVG for websites.
A short decision checklist
Choose raster when the image’s value comes from pixels and tonal detail. Choose vector when its value comes from shapes, scaling, and editability. Keep both when different platforms need different outputs.
If a PNG contains suitable shape-based artwork, prepare it for tracing, select True vector in PNG2SVG, and compare the result with the original before replacing anything.