Effective data compression of angiocardiographic static images with PABCEL method

Abstract

We implemented and applied a new compression method, called Pseudo-gradient Adaptive Brightness and Contrast Error Limitation (PABCEL) method, on singleimages coming from angiocardiographic f lms, recorded and digitized at the Haemodynanric Labs of the Cardiology Division of the Ospedali Riuniti, Bergamo. PABCEL algoritlim a i m at liinitirig maximum difference of brightness between corresponding pixels of the original image and the reconstructed one; it also limits the contrast error when considering corresponding pixels of the original and the reconstructed images on the Peano-Hilbert scan path. We applied our compression method to 168 images coming from 14 different angiocardiographic exams; with the lowest threshold values we obtained a mean conipressiori ratio of about 8:l: consulted cardiologists didn't identify significant diferences between original irriages and reconstructed ones. Qualitative and quantitative evaluation of obtained results has been carried out.

Compressing angiocardiographic still images: the new release of ITACA package for UNIX platforms

“…The third implemented irreversible compression method is named PABCEL [2]. It is somehow an evolution of PABEL: its basic principle is to limit, in an adaptive way, both the brightness error and the contrast error observed when considering, along the PHsp, consecutive pixels of the original image and of the reconstructed one.…”

“…In our previous studies we defined, implemented and experimented on angiocardiographic static images three irreversible compression techniques: BEL (Brightness Error Limitation), PABEL pseudo-gradient Adaptive Brightness Error Limitation) and PABCEL (Pseudogradient Adaptive Brightness and Contrast Error Limitation) [2,5].…”

“…These images were acquired in the Cath Labs of the Cardiology Division of Ospedali Riuniti di Bergamo, in Bergamo [2]. Each method, i. e. BEL, PABEL and PABCEL was investigated according to several values of the implied thresholds.…”

“…First, ITACA was developed to compress still angiocardiographic digital images written in the typical CARDIO 500 format (bitmap format with a 128-byte header) [2]. The new version also allows to compress digital images written in Targa format or as raw-file.…”

“…For this purpose we implemented an image-scan algorithm based on a function known as Peano-Hilbert curve [2,5]. This is a recursive algorithm that generates a Peano's curve, having an initial and an end point, on a discretized square beginning from four different basic scans.…”