Raster vs Vector Graphics Explained
Nearly every image you'll ever work with falls into one of two fundamentally different categories — raster or vector — and understanding the difference explains a lot of otherwise confusing image behavior, like why some logos scale perfectly to any size while a stretched photo turns blurry.
Raster: a fixed grid of pixels
A raster image (JPG, PNG, WEBP, and most other common formats) is stored as a grid of individual pixels, each with a specific color value. This is exactly how a camera or scanner naturally captures the world — as a dense grid of color samples — which is why virtually all photography and scanned content is raster by nature. The tradeoff is that a raster image is locked to the resolution it was captured or saved at; there's a fixed amount of detail, and displaying it larger than that native resolution means stretching existing pixels rather than genuinely adding new detail.
Vector: instructions, not pixels
A vector image (SVG being the most common web format) stores a set of mathematical instructions describing shapes — lines, curves, fills — rather than a fixed grid of colors. A vector image is redrawn fresh from those instructions at whatever size is needed, which is why it stays perfectly sharp at any scale: there's no fixed resolution to run out of, since nothing is being stretched.
Why you can't just pick whichever you prefer
The right choice isn't a matter of preference — it's determined by what the content actually is. A photograph has no clean way to be described as a set of shapes, so it must be raster. A simple logo made of clean shapes and flat colors can be described precisely as vector instructions, and doing so gives it a genuine advantage (infinite scalability, often smaller file size) that a raster version of the same logo wouldn't have.
When content needs to move between the two
Converting vector to raster (SVG to PNG, for instance) is straightforward — you're just asking the vector instructions to be drawn out at one specific size. Converting raster to vector is a fundamentally harder problem, since it requires inferring shapes and instructions from a fixed grid of pixels that may not cleanly correspond to simple shapes at all — this is why "vectorizing" a photo, for example, doesn't really work in any meaningful, faithful way.
SVG to PNG handles vector-to-raster conversion directly in your browser. If you're working with a raster image that needs more resolution rather than a true vector conversion, Image Upscaler is the more appropriate tool, since it works within raster's actual constraints rather than pretending the image is something it isn't.