Phase-only Correlation Algorithm Research Articles

Research on polarization dehazing through the coaxial and multi-aperture polarimetric camera

In this study, a coaxial and multi-aperture polarization imaging system was designed to obtain dehazed images under bad weather conditions, which could effectively utilize polarization information. The system can capture four polarization azimuth images simultaneously by integrating four polarizers with different transmission directions in front of the sub-apertures. The system can utilize energy of incident light effectively, as well as remain the image resolution of the camera. In order to solve the image registration problem, a translation registration method for sub-aperture polarized images was implemented, which was based on the phase-only correlation algorithm. Moreover, a polarization dehazing model suitable for this system is employed to remove the haze effect of the captured images. Further experimental data demonstrated that the system could achieve a pleasing visual effect, and its performance on image quality was certified by several objective evaluation means including the line spread function and quantified detail information. The core advantages of this system are real-time and the good image quality in terms of contrast, details, and clarity. The system can effectively adapt to the long-distance, high-resolution, and real-time imaging in bad weather conditions such as haze weather.

A 3.7×3.7mm² 310.9mW 105.2msec 512×512-Pixel Phase-Only Correlation Processor

The image recognition processor we propose implements the phase-only correlation (POC) algorithm. Its arithmetic-logic unit (ALU) is dynamically reconfigurable to any necessary circuitry for POC by itself. 2-stage cached-memory architecture (CMA) is developed so that high-radix batch processing is possible. By transforming the original POC algorithm into the optimum form for the dynamically reconfigurable ALU and 2-stage CMA, the proposed processor executes two-dimensional 512×512 pixel image recognition within 105.2msec and 310.9mW at 80MHz in an area 3.7×3.7mm². Its power consumption is over 11.3 times lower than that of previously reported work.

Application of the Laser Speckle-Correlation Method for Determining the Shrinkage Vector of a Light-cured Resin

The purpose of this study was to develop a method to monitor the free-shrinkage vectors of a light-cured resin using laser speckle contrast measurement. The laser speckle contrast measurement system comprised a semiconductor laser, a speckle analyzer, and a computer-controlled data acquisition system. A light-cured resin was condensed into a glass tube and irradiated using a curing unit, the light intensity of which was adjusted to either 100 or 600 mW/cm2. The speckle patterns obtained from the lateral surface of the specimen were monitored using a CCD camera connected to a computer. The speckle images were analyzed using a phase-only correlation algorithm, and movements of the pattern were traced. The speckle pattern revealed rapid movement almost immediately after light exposure was initiated, and the orientation of free-shrinkage vectors is dependent on light intensity. When the specimens were irradiated at the lower light intensity, the free shrinkage vectors were oriented towards the light source. On the other hand, when irradiated at the higher light intensity, the free-shrinkage vectors of these specimens tended to orient towards the bottom surface. The effectiveness of the employed method to determine free-shrinkage vectors is thus proven through the results of this study.