What characterizes a bitmap image?

A bitmap image is characterized by its composition of pixels, where each pixel represents the smallest unit of the image. These pixels each have binary values that define their color and intensity. The arrangement of these pixels forms the complete picture, with the level of detail depending on the resolution — the higher the number of pixels, the more detail can be captured.

In contrast, the other options focus on different types of images. For instance, options discussing shapes and lines, or mathematical formulas pertain more to vector graphics, which utilize geometric primitives rather than a grid of pixels. Vector graphics rely on mathematical expressions to represent images, allowing them to scale without loss of quality, unlike a bitmap image where scaling can lead to pixelation. Therefore, the defining feature of a bitmap image is clearly its pixel-based structure, making the identification of its binary values essential to understanding how bitmap images work.