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Wide Dynamic Range CMOS Cameras
Published in Krzysztof Iniewski, Circuits at the Nanoscale, 2018
Steve Collins, Bhaskar Choubey, Hsiu-Yu Cheng, Stephen Otim
The dynamic range of a conventional digital camera can be increased by acquiring several images with different integration times that are then merged to create a wide dynamic range image. However, this technique can only be applied easily to stationary scenes and it leads to large amounts of data per pixel. Both these problems can be solved using pixels with a logarithmic response that have a wide input dynamic range that is compressed using a nonlinear response that preserves the contrast information that is important to the human visual system. Wide dynamic range logarithmic pixels based upon load transistors operating in weak inversion have been known for many years. However, this type of pixel has several problems that have prevented them from being widely adopted. These problems can be overcome using an integrating pixel with a logarithmic response.
Combinational Digital Watermarking in the Spatial and Frequency Domains
Published in Frank Y. Shin, Digital Watermarking and Steganography, 2017
The PSNR is often used in engineering to measure the signal ratio between the maximum power and the power of corrupting noise. Because signals possess a largely wide dynamic range, we apply the logarithmic decibel scale to limit its variation. This measures the quality of reconstruction in image compression. However, it is a rough quality measure. In comparing two video files, we can calculate the mean PSNR. The PSNR is defined thus: PSNR=10log10(∑i=1N∑j=1N[h*(i,j)]2∑i=1N∑j=1N[h(i,j)−h*(i,j)]2)
Combinational Domain Digital Watermarking
Published in Frank Y. Shih, Digital Watermarking and Steganography: Fundamentals and Techniques, 2017
The PSNR is often used in engineering to measure the signal ratio between the maximum power and the power of the corrupting noise. Because signals possess a largely wide dynamic range, we apply the logarithmic decibel scale to limit its variation. It can measure the quality of reconstruction in image compression. However, it is a rough quality measure. In comparing two video files, we can calculate the mean PSNR. The peak signal-to-noise ratio is defined asPSNR=10log10(∑i=1N∑j=1N[h*false(i,jfalse)]2∑i=1N∑j=1N[hfalse(i,jfalse)−h*false(i,jfalse)]2).
A low complexity and high modularity design for continuously variable bandwidth digital filters
Published in International Journal of Electronics, 2023
Sushmitha Sajeevu, Sakthivel Vellaisamy
The proposed design can support a wide dynamic range of bandwidths. It was observed in the design of this continuously variable bandwidth digital FIR filter, for wide bandwidth, passband ripple increases. Similarly for narrow bandwidth case, stopband attenuation worsens. The order of the Pascal structure in the SRC can be updated easily since the Pascal structure design has obtained high modularity. It was observed that the first SRC has a control over the passband ripples and the second SRC has obtained a control over the stop band attenuation. Hence, increasing the order of the Pascal structure in first sampling converter gives better frequency response in wide bandwidth case. Similarly increasing the order of the Pascal structure in the second SRC gives better performance in the narrow bandwidth case.
Image Focus Measure Based on Polynomial Coefficients and Reduced Gerschgorin Circle Approach
Published in IETE Technical Review, 2023
Al Sameera B N, Vilas H. Gaidhane, J. Rajevenceltha
In this chapter, a transform-free, robust, and efficient image focus measure is presented. The proposed metric meets the requirements of the good focus measure presented in the literature. The logarithmic modified entropy quantifies the randomness caused by noise in the images, and a quality index is calculated. Experiments are conducted on synthetic and real-time images subjected to a variety of noise conditions. The results indicate that the proposed focus measure is monotonous and unimodal. In addition, it is sensitive to minute variations in noise and has a wide dynamic range. To demonstrate the correlation with human judgment, the performance of the proposed measure is compared with best-performing models. Moreover, the promising focus measure performance has been compared in terms of SRCC and KTCC on four datasets with the existing best-performing techniques.
A 17.5dB wide-dynamic range high-efficiency RF-to-DC power converter for wireless energy harvesting
Published in International Journal of Electronics Letters, 2022
In this work, we propose a wide-dynamic range high-efficiency differential RF rectifier, which is the key building block in WPR for ambient wireless powering. The proposed rectifier extends the dynamic range to allow the wireless range’s flexibility and improve the performance at low- and high-power levels by employing the low-threshold devices with dynamic body biasing of the feedback diodes to shift the efficient operating region to the low-power levels and minimise the leakage current. Moreover, the proposed design utilises the adaptive biasing technique using stacking diodes to control the conduction of the rectifying transistors at high-power levels. The proposed RF rectifier is implemented in 65 nm CMOS technology and achieves high efficiency over a wide dynamic range of input powers. The achieved dynamic range is 17.5 dB, which is the best reported DR compared to the state-of-the-art RF rectifiers with high efficiency. Moreover, the proposed design achieves high PCE at extremely low RF input power, which allows the ambient wireless powering.