Arguably the most important aspect of an image acquisition system is how images are represented. The SANE approach is to define a simple yet powerful representation that is sufficient for vast majority of applications and devices. While the representation is simple, the interface has been defined carefully to allow extending it in the future without breaking backwards compatibility. Thus, it will be possible to accommodate future applications or devices that were not anticipated at the time this standard was created.
A SANE image is a rectangular area. The rectangular area is subdivided into a number of rows and columns. At the intersection of each row and column is a quadratic pixel. A pixel consists of one or more sample values. Each sample value represents one channel (e.g., the red channel). Each sample value has a certain bit depth. The bit depth is fixed for the entire image and can be as small as one bit. Valid bit depths are 1, 8, or 16 bits per sample. If a device's natural bit depth is something else, it is up to the driver to scale the sample values appropriately (e.g., a 4 bit sample could be scaled by a factor of four to represent a sample value of depth 8).