What is the main characteristic of a raster image?

A raster image is primarily defined by its resolution-dependent nature, meaning that it is composed of a fixed number of pixels. When you enlarge a raster image, each individual pixel becomes larger, leading to a loss of quality and clarity, resulting in pixelation. This characteristic highlights the importance of resolution in raster images; they are best used at their intended size.

In contrast, images made up of paths, such as vector images, are not resolution-dependent. They can be scaled indefinitely without loss of quality because they are based on mathematical expressions. While raster images can support transparency, this feature is not a defining characteristic since transparency can also be present in vector formats. Additionally, raster images are not inherently designed for easy scalability; rather, they require careful consideration of resolution to maintain quality, which is fundamentally different from how scalable vector images function. Therefore, recognizing that raster images are resolution-dependent is key to understanding their limitations and best-use scenarios in graphic design.