We are interested in making computer generated holographic spatial filters on a graphics device which can plot only a limited number of points (such as a storage-tube terminal). The Generalized Binary Computer Generated Hologram is an algorithm which makes efficient use of available plotting points, thus making it attractive for use with these limited plotters. In this paper we study the nature of the set of complex amplitudes one can code with this algorithm. Our main topic is amplitude quantization noise. We show that, since the quantization steps vary in size, the optimum signal normalization is not necessarily that which uses all the quantization steps. We analyze the amplitude quantization noise in several types of real-valued holograms to demonstrate this behavior. We give the results of a measurement of errors in dot size and dot position on a storage tube terminal, and relate this noise to our analysis of amplitude quantization noise.