An open-loop adaptive optics (AO) system for retinal imaging was constructed using a liquid crystal spatial light modulator (LC-SLM) as the wavefront compensator. Due to the dispersion of the LC-SLM, there was only one illumination source for both aberration detection and retinal imaging in this system. To increase the field of view (FOV) for retinal imaging, a modified mechanical shutter was i...

We present a comprehensive framework for wave-equation illumination analysis and introduce a target-oriented illumination correction that simultaneously accounts for limited acquisition aperture and, locally, compensates for the so-called normal operator in inverse scattering to yield a “true-amplitude” image of reflectivity or reflection coefficient, while minimizing (orientation dependent) ph...

Building a mathematical model of uneven illumination and contrast is difficult, even impossible. This paper presents a novel image balancing method for a satellite image. The method adjusts the mean and standard deviation of a neighborhood at each pixel and consists of three steps, namely, elimination of coarse light background, image balancing, and max-mean-min radiation correction. First, the...

In this paper a non-parametric model based on Wasserstein CNN is proposed for color correction. It is suitable for large-scale remote sensing image preprocessing from multiple sources under various viewing conditions, including illumination variances, atmosphere disturbances, and sensor and aspect angles. Color correction aims to alter the color palette of an input image to a standard reference...

We report an intrinsic image distortion in microwave-induced thermoacoustic tomography. The distortion, due to microwave diffraction in the object to be imaged, leads to nonuniform excitation of acoustic pressure during microwave illumination. Both numerical simulations and phantom experiments demonstrate this phenomenon. A method of partial correction is also provided.

This report presents the results of a partial differential equation (PDE)-based image enhancement algorithm, for dynamic range compression and illumination correction in the absence of the logarithmic function. The proposed algorithm combines forward and reverse flows in a PDE-based formulation. The experimental results are compared with algorithms from the literature and indicate comparable pe...

This paper presents an application of Kohonen's self-organizing feature maps (SOM) for solving the problem of color constancy. The main problem is to evaluate the transformation between collections of color-points forming diierently shaped clouds in color space under changing illumination. The main idea is to embed appropriate 3D coordinate systems into these clouds by self-organization, and so...

This paper presents a new approach for automatic image color correction, based on statistical learning. The method both parameterizes color independently of illumination and corrects color for changes of illumination. The motivation for using a learning approach is to deal with changes of lighting typical of indoor environments such as home and office. The method is based on learning color inva...

To solve the problem of indoor surveillance, this paper is concerned about the framework that allows the detection of moving objects based on IP camera. The current background subtraction algorithms cannot correctly classify foreground and background if there are sudden illumination changes. To eliminate the influence of illumination changes, intensity flicker correction technique is employed b...

The problem of differential terrain illumination on satellite imagery has been investigated for at least 20 years and has not been solved satisfactorily. Most past research has been conducted on Landsat imagery where the look angle is nadir. There is no research on topographic correction of IKONOS imagery, which has a higher spatial resolution. The high spatial resolution of IKONOS imagery requ...