ANALYSIS OF DISTORTION CHARACTERISTICS IN IMAGE COMPRESSION BY MODERN DCT-BASED METHODS

Abstract

Expedience of studying statistical and spatial spectral characteristics of distortions introduced by methods of image lossy compression based on the discrete cosine transform is substantiated. It is shown that the law of distortion distribution is close to normal at small values of compression ratio (CR), but it can significantly differ from normal for large values of CR. The distortions introduced are practically uncorrelated or slightly correlated. The level of distortions introduced is locally changing and the largest distortions are observed in locally active areas of images. At the same quantization step of DCT coefficients, the statistical characteristics of the introduced distortions can differ substantially.

Keywords

• аналіз
• спотворення
• стиснення з втратами