What is the difference between signed and unsigned bits in a raster?

In raster data representation, the distinction between signed and unsigned bits is crucial for how the data is interpreted and what values can be represented. Unsigned bits specifically refer to binary representations that can only express non-negative values. This means that the entire range of bits is dedicated to representing positive numbers, including zero. For example, in an 8-bit unsigned integer, the values range from 0 to 255.

On the other hand, signed bits allow for both positive and negative values by utilizing a specific bit (usually the most significant bit) to indicate the sign of the number. This means that, if we consider an 8-bit signed integer, the range would be from -128 to 127.

Thus, the correct choice captures the essential characteristic of unsigned bits, which is their inability to represent negative values, making them distinct from their signed counterparts.

Options suggesting that signed bits are more efficient in storage or indicating no difference between signed and unsigned bits would be misleading because storage efficiency is determined more by the specific application requirements and data types than by a simple classification of signed versus unsigned.