No-reference image quality assessment based on DCT domain statistics
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- 作者：Tomá ; s Br ; ã ; o ; Maria Paula Queluz
- 关键词：Image quality ; No-reference quality metric ; DCT coefficient statistics ; Parameter estimation
- 刊名：Signal Processing
- 出版年：2008
- 出版时间：April 2008
- 年：2008
- 卷：88
- 期：4
- 页码：822-833
- 全文大小：353 K
文摘
This paper proposes a no-reference quality assessment metric for images subject to quantization noise in block-based DCT (discrete cosine transform) domain, as those resulting from JPEG or MPEG encoding. The proposed method is based on natural scene statistics of the DCT coefficients, whose distribution is usually modeled by a Laplace probability density function, with parameter λ. A new method for λ estimation from quantized coefficient data is presented; it combines maximum-likelihood with linear prediction estimates, exploring the correlation between 26a18849c3314f5c7f"" title=""Click to view the MathML source"">λ values at adjacent DCT frequencies. The resulting coefficient distributions are then used for estimating the local error due to lossy encoding. Local error estimates are also perceptually weighted, using a well-known perceptual model by Watson. When confronted with subjective quality evaluation data, results show that the quality scores that result from the proposed algorithm are well correlated with the human perception of quality. Since no knowledge about the original (reference) images is required, the proposed method resembles a no-reference quality metric for image evaluation.