Illumination problem

About: Illumination problem is a research topic. Over the lifetime, 93 publications have been published within this topic receiving 5859 citations.

A processing method for underground image of uneven illumination based on homomorphic filtering theory

Abstract: Traditional homomorphic filtering function is based on high pass filler,and images processed by the function are dark.The paper analyzed image filtering result by traditional low pass filter at cut-off frequency radius of 5,and got a conclusion that illumination component mainly distributes in low-frequency range of 0~5 radius.It introduced a design scheme of novel homomorphic filter,and proposed a processing method for underground image of uneven illumination based on homomorphic filtering theory.The method uses traditional low pass filter to restrain low-frequency components and traditional high pass filter to strengthen high-frequency components,divides range of low-frequency components of underground images into two sections,and uses different processing methods in the two low-frequency sections,namely restraining low-frequency components in the range of restraining radius of low-frequency and making low-frequency components invariant which are between restraining radius of low-frequency and strengthening radius of high-frequency,so as to avoid restraining low-frequency component overly.The testing result showed that the method solves uneven illumination problem as well as avoids weakening overall illumination of underground images overly,which has good effect.

Illumination compensation methods for automatic fiber connector inspection

Abstract: Unevenly distributed image illumination is a problem in an automatic machine visual inspection system used for fiber connector defect detection. This unevenly distributed illumination makes it difficult to find an appropriate horizontal threshold to convert a gray-scale image to a binary image to separate surface defects, such as blobs and scratches, from the background of the connector. This paper proposes some effective methods to compensate the unevenly distributed illumination problem so that standard image processing methods can be used effectively to detect the defects of the fiber connectors.

Solving the illumination problem with heuristics

Abstract: In this article we propose optimal and quasi optimal solutions to the problem of searching for the maximum lighting point inside a polygon P of n vertices. This problem is solved by using three different techniques: random search, simulated annealing and gradient. Our comparative study shows that simulated annealing is very competitive in this application. To accomplish the study, a new polygon generator has been implemented, which greatly helps in the general validation of our claims on the illumination problem as a new class of optimization task.

Adaptive mesh generation for progressive radiosity: A ray‐tracing based algorithm.

Abstract: The radiosity method is one of the most popular rendering algorithms. It allows to simulate interreflections of light accurately between surfaces as energy transfers are well designed. However, this algorithm and its derivatives need to break scenes into a relatively large number of small elements to approximate the illumination function. Even with a very large number of elements, not all the illumination effects can be simulated. In fact, there are always artefacts when modelling sharp shadows, besides shadows falling between mesh vertices can be missed entirely. To reduce the computational cost of such methods and to increase the accuracy of the radiosity solution, adaptive mesh generation is well suited. In this paper, we present a ray-tracing based algorithm for adaptive mesh generation which resolves all the illumination problems without lengthening computation time too much. This method allows a small number of initial elements and increases element density in critical locations while solving the illumination problem.

An Enhancement Algorithm for Non-uniform illumination Image based on two Homomorphic Filters

Abstract: To solve the non-uniform illumination problem of digital images, an enhancement algorithm based on segmenting non-uniform illumination image into two sub images and filtering separately is proposed. The method how to segment the non-uniform illumination image into two sub images and fix on the cut-off frequency of homomorphic filter is studied. The experiment shows image enhancement effect of the proposed algorithm in this paper.