An efficient subband image decomposition method for monochrome and color images made possible by mathematical morphology is described. The input signal spectrum is decomposed into four-subband and two-subband images by using two different sets of structuring elements. Then each band image can be decimated and coded effectively for data transmission. This subband pyramid scheme preserves the number of pixels as that in the original image Also, the data structure itself is very compact. The advantages of morphology over the linear filtering approach are its direct geometric interpretation, simplicity, and efficiency in hardware implementation. Some image examples are presented to show the effectiveness of this approach.
"Subband decomposition of monochrome and color images by mathematical morphology," Optical Engineering 30(7), (1 July 1991). https://doi.org/10.1117/12.55892