No abstract

Image scrambling is used to make images visually unrecognizable such that unauthorized users have difficulty decoding the scrambled image to access the original image. This article presents two new image scrambling algorithms based on Fibonacci p-code, a parametric sequence. The first algorithm works in spatial domain and the second in frequency domain (including JPEG domain). A parameter, p, is used as a security-key and has many possible choices to guarantee the high security of the scrambled images. The presented algorithms can be implemented for encoding/decoding both in full and partial image scrambling, and can be used in real-time applications, such as image data hiding and encryption. Examples of image scrambling are provided. Computer simulations are shown to demonstrate that the presented methods also have good performance in common image attacks such as cutting (data loss), compression and noise. The new scrambling methods can be implemented on grey level images and 3-color components in color images. A new Lucas p-code is also introduced. The scrambling images based on Fibonacci p-code are also compared to the scrambling results of classic Fibonacci number and Lucas p-code. This will demonstrate that the classical Fibonacci number is a special sequence of Fibonacci p-code and show the different scrambling results of Fibonacci p-code and Lucas p-code.

Optical wireless LANs have the potential to provide bandwidths far in excess of those available with current or planned RF networks. There are several approaches to implementing optical wireless systems, but these usually involve the integration of optical, optoelectronic, and elec-I Figure 5. Demonstration system optomechanics. Transmitter optomechanics Receiver optomechanics Detector array flip-chip bonded to CMOS integrated circuit Ceramic package Ceramic package Source array flip-chip bonded to CMOS integrated circuit

This paper presents the design and measurement results of two avalanche photodiode structures (APDs) and a novel frequency-mixing transimpedance amplifier (TIA), which are key building blocks towards a monolithically integrated optical sensor front end for near-infrared (NIR) spectroscopy applications. Two different APD structures are fabricated in an unmodified 0.18 \im CMOS process, one with a shallow trench isolation (STI) guard ring and the other with a P-well guard ring. The APDs are characterized in linear mode. The STI bounded APD demonstrates better performance and exhibits 3.78 A/W responsivity at a wavelength of 690 nm and bias voltage of 10.55 V. The frequency-mixing TIA (FM-TIA) employs a T-feedback network incorporating gate-controlled transistors for resistance modulation, enabling the simultaneous down-conversion and amplification of the high frequency modulated photodiode (PD) current. The TIA achieves 92 dS Ω conversion gain with 0.5 V modulating voltage. The measured IIP(3) is 10.6/M. The amplifier together with the 50 Ω output buffer draws 23 mA from a1.8 V power supply.

This paper presents design and measurement results of a fully integrated optical sensor for phase and amplitude detection of RF modulated optical signals up to 110 MHz in the near-infrared (NIR) region (650-850 nm) for use in frequency-domain spectroscopy instruments. The sensor consists of an NIR-sensitive photodetector monolithically integrated with a front-end analog amplifier and signal processing circuitry for amplitude and phase detection in an unmodified complementary metal oxide semiconductor (CMOS) process. A high-gain, low-noise differential transimpedance amplifier (TIA) is implemented to amplify the photocurrent signal. Amplitude and phase resolution are evaluated with a 690 nm laser diode modulated at 100 MHz. The amplitude response exhibits 2.2 mV Wresolutionwith0.4%linearity.The measured amplitude output noise is 72 V. The proposed phase detector detects 0 -360 phase difference with a measured average phase resolution of 4.8 mV/degree and 255 V output noise. The sensor is implemented in a 180 nm CMOS technology and consumes 23.4 mW from a 1.8 V supply voltage.