Methods and apparatus for providing JPEG decoder functions are described. In particular, features and methods of the present invention are directed to an efficient way of implementing a non-common decoding path function used in an MQ-coder, such as the type used to decode JPEG-2000 images. The methods of the present invention are well suited for implementation on general purpose computers such as conventional personal computers (PCs) and can provide improved decoding speed, compared to known systems which use processing branches as part of a non-common decoding path function by reducing and, in some implementations completely avoiding, branches. Thus, branch prediction penalties associated with known decoding schemes are reduced or avoided leading, in many cases, to faster decoding rates when using a general purpose processor of a given speed or computational capability.