This chapter provides an overview of the considerations for specifying Computer-generated hologram (CGH) and encoding them with different representation techniques. CGH provides an alternative approach to forming a hologram. The actual writing of the CGH is accomplished with a digital device such as a printer, lithography, or spatial light modulator. The chapter discusses the requirements for sampling, the discrete Fourier transform used to describe beam propagation and diffraction, and several encoding and CGH writing methods. It describes two different CGH encoding methods: binary detour phase method that encodes both amplitude and phase and the binary phase hologram by Lee. However, in the case of the CGH, the pattern is sampled and converted into a “binary” transmittance function. However, with the generalized CGH approach, the image or optical transformation may be more complicated and requires a numerical technique to define the transmittance phase function.