Grazing incidence polarized light imaging of footwear prints

2019, Volume 20, Issue 11

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Frontiers of Information Technology & Electronic Engineering >> 2019, Volume 20, Issue 11 doi: 10.1631/FITEE.1800383

Grazing incidence polarized light imaging of footwear prints

Affiliation(s): Shenzhen Key Laboratory for Minimal Invasive Medical Technologies, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; Department of Biomedical Engineering, Tsinghua University, Beijing 100084, China; Department of Physics, Tsinghua University, Beijing 100084, China; Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; Criminal Police Team, Municipal Public Security Bureau, Zhuhai 519000, China; Tsinghua-Berkeley Shenzhen Institute, Shenzhen 518071, China; less

Accepted: 2019-12-10 Available online: 2019-12-10

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Abstract

Footwear prints are important evidence in criminal investigation. They represent changes in the surface morphology due to disturbance to fine distributions. Existing non-contact optical detection methods usually measure the light intensity contrasts between the footwear prints and the ground, which can be enhanced by grazing incident illumination. We take images of footwear prints on different types of floors using a commercial single lens reflex color camera. Results show that adding linear polarizers in front of the camera lens and light source improves the contrast of footwear print images. The best contrasts are achieved in degree of linear . In addition, the three-color channels of the camera can be used to examine the spectral features of the images. According to the experimental results, the best contrast is obtained at the blue channel. The current work shows that grazing incidence polarized light imaging can effectively enhance the contrast of the footwear prints against the floors, which would help obtain footwear evidence in criminal investigation.

Keywords

偏振 ; 图像增强 ; 散射 ; 粒子

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