Transform coding of arbitrarily shaped regions in ultrasonic data

A new transform coder for arbitrarily shaped regions in ultrasonic data is proposed. In the encoder, a block-based DCT(Discrete Cosine Transform) is applied to the resulting image block after shifting pixels within the image segment to block border and padding the mean value of the pixels to empty region. For reducing the transmission bit rate, the transform coefficients located in padded region are truncated and only the remaining transform coefficients are transmitted to the decoder. In the decoder, the transform coefficients truncated in the encoder are recovered using received transform coefficients and a block-based inverse DCT is performed.