An algorithm operating upon a sequence of discrete-time sampled data, designed to pass signals with selected temporal or spatial frequencies while attenuating signals with other temporal or spatial frequencies. Such filters are often used to pass desired signals while suppressing noise or interfering signals. Common types are low-pass filters, which suppress high-frequency energy; high-pass filters, which reject low-frequency energy; and bandpass filters, which reject low- and high-frequency energy, and pass only a limited range of frequencies in between.