Robust Sharpness Metrics Using Reorganized DCT Coefficients for Auto-Focus Application

2015 ◽  
pp. 172-187
Author(s):  
Zheng Zhang ◽  
Yu Liu ◽  
Xin Tan ◽  
Maojun Zhang
Keyword(s):  
Dct Coefficients ◽  
Auto Focus ◽  
Sharpness Metrics

Passive Auto-Focus Algorithm for Correcting Image Distortions Caused by Gas Flow in High-Temperature Measurements of Surface Phenomena

2012 ◽  
Vol 17 (4) ◽  
pp. 379-384 ◽  
Author(s):  
Krzysztof Strzecha ◽  
Tomasz Koszmider ◽  
Damian Zarębski ◽  
Wojciech Łobodziński
Keyword(s):  
High Temperature ◽  
Gas Flow ◽  
Temperature Measurements ◽  
Surface Phenomena ◽  
Auto Focus ◽  
High Temperature Measurements

Abstract In this paper, a case-study of the auto-focus algorithm for correcting image distortions caused by gas flow in high-temperature measurements of surface phenomena is presented. This article shows results of proposed algorithm and methods for increasing its accuracy.

A robust and high capacity data hiding method for JPEG compressed images with SVD-based block selection and advanced error correcting techniques

2021 ◽  
pp. 1-11
Author(s):  
Kusan Biswas
Keyword(s):  
Data Hiding ◽  
High Capacity ◽  
Error Correcting Codes ◽  
Human Vision ◽  
Data Embedding ◽  
Compressed Images ◽  
Matrix Encoding ◽  
Dct Coefficients ◽  
Capacity Data ◽  
Value Decomposition

In this paper, we propose a frequency domain data hiding method for the JPEG compressed images. The proposed method embeds data in the DCT coefficients of the selected 8 × 8 blocks. According to the theories of Human Visual Systems  (HVS), human vision is less sensitive to perturbation of pixel values in the uneven areas of the image. In this paper we propose a Singular Value Decomposition based image roughness measure (SVD-IRM) using which we select the coarse 8 × 8 blocks as data embedding destinations. Moreover, to make the embedded data more robust against re-compression attack and error due to transmission over noisy channels, we employ Turbo error correcting codes. The actual data embedding is done using a proposed variant of matrix encoding that is capable of embedding three bits by modifying only one bit in block of seven carrier features. We have carried out experiments to validate the performance and it is found that the proposed method achieves better payload capacity and visual quality and is more robust than some of the recent state-of-the-art methods proposed in the literature.

A Two-Stage Time-Domain Autofocus Method Based on Generalized Sharpness Metrics and AFBP

2021 ◽  
pp. 1-13
Author(s):  
Tao Zhang ◽  
Guisheng Liao ◽  
Yachao Li ◽  
Tong Gu ◽  
Tinghao Zhang ◽  
...  
Keyword(s):  
Time Domain ◽  
Two Stage ◽  
Sharpness Metrics

A DCT-Domain System for Digital Watermarking

2013 ◽  
Vol 321-324 ◽  
pp. 2609-2612
Author(s):  
Yan Liang ◽  
Gao Yan ◽  
Chun Xia Qi
Keyword(s):  
Signal Processing ◽  
Digital Watermarking ◽  
Copyright Protection ◽  
Random Sequence ◽  
Multimedia Data ◽  
Dct Domain ◽  
Digital Document ◽  
Dct Coefficients ◽  
Processing Techniques ◽  
Signal Processing Techniques

Digital watermarking has been proposed as a solution to the problem of copyright protection of multimedia data in a networked environment. It makes possible to tightly associated to a digital document a code allowing the identification of the data creator, owner, authorized consumer, and so on. In this paper a new DCT-domain system for digital watermarking algorithm for digital images is presented: the method, which operates in the frequency domain, embeds a pseudo-random sequence of scrambled image in a selected set of DCT coefficients. After embedding, the watermark is adapted to the image by exploiting the masking characteristics of the human visual system, thus ensuring the watermark invisibility. By exploiting the statistical properties of the embedded sequence, the mark can be reliably extracted without resorting to the original uncorrupted image. Experimental results demonstrate that the watermark is robust to several signal processing techniques, including JPEG compression, cut, fuzzy, addition of noise, and sharpen.

The Study of Auto-Focus System for Biomedical Digital Microscope

2009 ◽  
Author(s):  
Chen-Song Chiang ◽  
Yu-Jen Chen ◽  
Ming-Shing Young ◽  
Ming-Han Hsieh ◽  
Yun-Zhe Hsieh ◽  
...  
Keyword(s):  
Digital Microscope ◽  
Auto Focus
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