Nearly lossless compression of color still images and its performance evaluation
Akira Okumura, Junji Suzuki · Electronics and Communications in Japan (Part I Communications) · 1996
Abstract Existing image coding systems can be categorized into lossy and lossless coding methods. Nearly lossless compression, which attains both higher compression performance than lossless compression and higher image quality than lossy compression, is required in applications that include medicine and printing. This paper proposes a nearly lossless coding method in which distortion is restricted to within a predetermined range. The RGB input signals are transformed into one luminance and two chrominance components; the magnitudes of these luminance and chrominance components are adjusted in the encoder so that the reconstructed RGB signals have minimum distortion after inverse color transformation in the decoder. The prediction residual signals of these level‐adjusted components are entropy coded. As a result, the reconstructed RGB signals have coding distortion levels of only +1 or ‐1. This restricted distortion never accumulates even if encoder/decoder couples are connected in tandem because all encoders and decoders operate in synchrony.