Evaluation of Boundary Errors from Quantizing Images with the Discrete Wavelet Transform

摘要

All wavelet filters with a length greater than two extend beyond an image's boundary during the calculation of at least one wavelet coefficient using the discrete wavelet transform (DWT). The conventional approach to this boundary effect problem is to extend a signal beyond its boundaries. Artifacts, in the form of visual edges, can be produced at the boundaries when wavelet coefficients associated with an extended signal are quantized to increase compression. The problem is more pronounced when images are decomposed into subimages that are processed independently. This paper evaluates boundary errors using proposed measures.