The Acquirement Of Vein Image And Its Contrast Enhancement Based On The Optical Angular Spectrum Theory

The near-infrared (NIR) imaging method was required in clinic, such as the venipuncture and diagnosis of some diseases related to the vein. Current vein imaging systems are costly and some cannot get a well effect, thus limited its market promotion.In this thesis, a setup combined a NIR light-emitting diode (LED), with a centered wavelength at 850nm±30nm, and a charge coupled device (CCD) camera were chosen to acquire the infrared image of vein. A filtering algorithm was carried out on the infrared image based on the optical angular spectrum theory. And we also made an improvement of Unsharp masking (USM), using the bandpass filter instead of the highpass or Gaussian filter which was mostly used in USM.The results demonstrated that the images processed by our proposed methods were more effective in vessel enhancement and were of higher qualities.Combine with the theory and experimental results, we proved that the proposed methods based on the optical angular spectrum theory is effective in the contrast enhancement of the vein image.