In this paper, we propose the application of the L-curve and curvature to the super resolution image restoration problem. L-curve criterion is used to estimate regularization parameters. However, the computational of the L-curve is quiet costly for large size problems. The Lanczos algorithm and Gauss quadrature are used to reduce the computational cost. But the many iterations of Lancros algorithm results in the expensive cost of L-curve. The paper develops an approximate technique that can be used to get the proper the iterative times of Lancros algorithm with L-curvature. The technique shows that L-curve and curvature can be computed fairly inexpensively by partial Lanczos algorithm. Then a suitable value of the regularization parameter is determined from L-curve.
Conventional objective image assessment metrics, such as mean squared error and peak signalto-noise ratio, which only calculates pixel-based differences between the original and the degraded images, are not in agreement with the human vision. In this paper, we present an improved objective full-reference image quality assessment method, called the multiscale and multidirectional visibility differences (MMVD) predictor. The proposed MMVD metric considers multiscale and multidirectional visibility differences in the domain of the discrete nonseparable shearlet transform, which emulates the multichannel structure of information processing of the human vision system. In the process of constructing the visual just noticeable difference threshold in the shearlet domain, the contrast sensitivity function and the visual masking effect which are important properties of the human visual perception are considered simultaneously to approximate the sensitivities of human visual responses. Both contrast masking and entropy masking are considered to tackle the visual masking issue. All subbands of the shearlet transform are evaluated, and perceptual errors of subbands are pooled together to yield the objective quality index of a distorted image. The extensive validation experiments are conducted on five public image databases, namely, TID2008, TID2013, CSIQ, IVC, and LIVE. The experimental results demonstrate the proposed method is well coherent with human perception and has better performance compared to the several state-of-the-art image quality metrics.INDEX TERMS Discrete nonseparable shearlet transform, image quality assessment, human visual system, visual masking, visual just noticeable difference threshold.
Ink-jet printing is an important part of the digital printing system; it has been widely used in various fields because of its wide adaptability, high-speed intelligent and low pollution. This paper chooses a kind of print head produced in XAAR company which works in dropping on demand manner. Firstly we introduce the hardware design of interface circuit and so on. Then we realize the functional modules of high-speed data interface of ink-jet printing system. At last, we focus on the design and implementation of high-speed data interface of ink-jet printing system.
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