A new set of boundary-handling algorithms has been developed for discrete wavelet transforms in the ISO/IEC JPEG-2000 Still Image Coding Standard. Two polyphase component extrapolation policies are specifed: a constant extension policy and a symmetric extension policy. Neither policy requires any computations to generate the extrapolation. The constant extension policy is a low-complexity option that buffers just one sample from each end of the input being extrapolated. The symmetric extension policy has slightly higher memory and conditional-logic requirements but is mathematically equivalent to wholesample symmetric pre-extension when used with whole-sample symmetric filter banks. Both policies can be employed with arbitrary lifted filter banks, and both policies preserve resolution scalability and reversibility. These extension policies will appear in Annex H, "Transformation of images using arbitrary wavelet transformations," in Part 2 ("Extensions") of the JPEG-2000 standard.