A Peano-Hilbert derived algorithm for compression of angiocardiographic images

The authors implemented some irreversible compression techniques on single images coming from angiocardiographic films. They used two different types of threshold on the brightness difference between corresponding pixels of the original image and the reconstructed one. The two methods were brightness error limitation (BEL) and pseudo-gradient adaptive BEL (PABEL). The results of irreversible compression were coded by a reversible compression method based on Lempel-Ziv algorithms. To take advantage of local properties of angiographic images a scan path based on Peano-Hilbert plane-filling curve was implemented. Applying the compression techniques to some 80 different images the authors obtained a mean compression of more than 6:1. A cardiologist did not identify significative diagnostic differences between original images and reconstructed ones