Design and implementation of a scene-dependent dynamically selfadaptable wavefront coding imaging system

A computational imaging system based on wavefront coding is presented. Wavefront coding provides an extension of the depth-of-field at the expense of a slight reduction of image quality. This trade-off results from the amount of coding used. By using spatial light modulators, a flexible coding is achieved which permits it to be increased or decreased as needed. In this paper a computational method is proposed for evaluating the output of a wavefront coding imaging system equipped with a spatial light modulator, with the aim of thus making it possible to implement the most suitable coding strength for a given scene. This is achieved in an unsupervised manner, thus the whole system acts as a dynamically selfadaptable imaging system. The program presented here controls the spatial light modulator and the camera, and also processes the images in a synchronised way in order to implement the dynamic system in real time. A prototype of the system was implemented in the laboratory and illustrative examples of the performance are reported in this paper.Program summaryProgram title: DynWFC (Dynamic WaveFront Coding)Catalogue identifier: AEKC_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKC_v1_0.htmlProgram obtainable from: CPC Program Library, Queenʼs University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 10 483No. of bytes in distributed program, including test data, etc.: 2 437 713Distribution format: tar.gzProgramming language: Labview 8.5 and NI Vision and MinGW C CompilerComputer: Tested on PC Intel® Pentium®Operating system: Tested on Windows XPClassification: 18Nature of problem: The program implements an enhanced wavefront coding imaging system able to adapt the degree of coding to the requirements of a specific scene. The program controls the acquisition by a camera, the display of a spatial light modulator and the image processing operations synchronously. The spatial light modulator is used to implement the phase mask with flexibility given the trade-off between depth-of-field extension and image quality achieved. The action of the program is to evaluate the depth-of-field requirements of the specific scene and subsequently control the coding established by the spatial light modulator, in real time.

► A wavefront coding imaging system is presented employing a spatial light modulator.
► The system estimates the amount of optical defocus of the imaged scene.
► Optimal coding strength is implemented according to a look-up table.
► Defocus changes are successfully detected.
► The unsupervised and real-time operation is demonstrated experimentally.