Study On Depth From Focus Technology

Three-dimensional surface topography measurement has a very important value. It has a wide range of applications in the automated processing, product quality testing, physical profiling, computer-aided design, biomedical, machine vision, art sculptures and other fields. It has become a hot research issue in recent years. With the development of science and technology, three-dimensional image measurement technique plays a role in more and more areas. It is widely used in non-contact optical measurement method because of its non-destructive, fast measure. This paper compares the characteristics of active and passive mode. The passive mode measurement based on depth of field becomes a research hotspot because of the low hardware request.This paper focused on non-contact three-dimensional depth of field-based measurement method. Recovery of the three-dimensional topography is done from focus (depth from focus DFF). It is characterized by the use of an ordinary microscope, the depth reconstructed from a series of different focus plane images. Instead of additional hardware cost, we can deal with digital images to obtain the three-dimensional appearance. The benefits are that the hardware is simple, non-contact measuring.This paper is divided into six chapters, focuses on the status, existing problems, algorithm, simulation and implementation of the measurement system hardware and software design and implementation of depth from focus. The software of electrical control, image acquisition and simulation system is designed using C + + builder. In this paper, the following work is accomplished:1 The electric part of the microscope hardware framework is designed according to the requirement of the actual measurement.2 The simulation system of depth of field is designed and implemented in according with geometrical optics model. The accuracy of the optical model is verified through the comparison with the real images and simulated images. The simulation system improves the efficiency of problem-solving. 3 The commonly used methods of depth form focus is compared and analyzed. in view of the disadvantages, the key point method is proposed. Result shows that the method improves the measurement accuracy. The measurement error is further reduced by removing the pre-treatment image.4 A method of three-dimensional depth form focus measurement for color image is proposed. It is used for color image and achieved good results.