Gradient-based block truncation coding
Mahmoud K. Quweider, Ezzatollah Salari · Electronics Letters · 1995
A new gradient-based block truncation coding (BTC) algorithm is presented. Combined with a simple two-way classification, the algorithm shows a substantial improvement in the visual image quality demonstrated by edge preservation and reduction of the staircase effect. At the same time, significant reduction in bit rate is achieved. A user-defined threshold allows bit rates in the range 0.70 – 1.5, depending on the quality level desired.