Airport baggage x ray machine for luggage imaging are using dual energy metal detector gate, the baggage x ray machine of high-energy x-rays generated by more than 100 kv high anode voltage, through the objects, the higher the density of the material (such as metal cutting tools, etc.), imaging and darker. And low energy of baggage x ray machine is formed by low anode voltage of 80 kv, and can detect material effective atomic number and the thickness of the object, such as explosives in carbon, nitrogen, oxygen, etc. Subject is usually based on baggage x ray machine monitor low high-energy fusion image of luggage, confirmed in passengers luggage is in possession of dangerous goods, such as knives, guns, etc., when the image is not clear or suspicious items, then observe low, high-energy image respectively. Therefore, baggage x ray machine image quality directly affect the security personnel working accuracy and efficiency.
Currently in view of the x ray Scanner image enhancement methods mainly include: histogmm equalization (HE), gray - level grouping (GLG) and going gray level transform (SGT), etc. HE method can expand the baggage x ray machine, the dynamic range of image and improve the contrast of the image. Due to the continuity of the method itself, for discrete digital image histogram can only do the approximate uniform distribution, the image of gray levels is not clear, fuzzy edge.GLG method is to put the metal detectors for sale image pixels in the grayscale redistribution and establish the enhancement function, gray level transformation of image to improve image quality, but the method of noise of low contrast image quality improvement is not obvious. Using sine gray-scale transformation enhancement processing, improve the sharpness of the image after processing, but the contrast is low, the details are still not clear enough.
This paper presents a two-stage baggage baggage scanner price method, the first advantage of the characteristics of wavelet transform and ICA, combine its for dual energy X-ray image denoising and fusion, implementation level enhancement. Then apply the proposed adaptive to secondary image fusion enhancement sine gray-scale transformation, further improve the image resolution, low contrast area easier to security personnel to recognize the items in the luggage. The experimental results show that the method can effectively improve the x ray machine for sale image clarity, has good generalization ability.
According to the baggage x ray machine image characteristics, this paper adopts two levels of image enhancement methods. First low to high energy X-ray image fusion to achieve the first level enhancement, multi-scale wavelet transform fusion method is based on the multi - scale wavelet - ICA (MSwICA), after the fusion image are enhanced adaptive sine gray-scale transformation to achieve the second.
Specific process description is as follows:
1) Image fusion: the ICA in the X Ray inspection supplier got very good application in signal denoising, shows superior performance.
2) Image enhancement: using the adaptive sine gray-scale transformation to enhance of the fused image, the image of different gray level according to the different sine transform index factor. The original image was divided into two or more parts, using ASGT method enhanced processing in each section. ASGT as a post-processing method, its main purpose is to further strengthen the baggage x ray machine image shows low contrast content in the area, different regions use different sine transform index factor, in order to achieve better effect, easy to security personnel identification inside the bag.
