By using dual-energy x-ray imaging, materials can be identified. This method has specific application in security iection. In this method the effective atomic number of materials are calculated based on the two images obtained with different x-ray spectrum. The calculated effective atomic number suffered by errors due to noise. This error depends on the thickness of materials and their effective atomic number and also on imaging parameters such as x-ray tube voltage and x-ray tube current. There is not any proposed method for evaluating the justify; LINE-HEIGHT: 15pt; TEXT-INDENT: 0in; MARGIN: 0in 0in 0pt; unicode-bidi: embed; DIRECTION: ltr; mso-line-height-rule: exactly" For calculating the effective atomic number, a Look-Up-Table has been constructed based on experimental measurement. Complex materials are simulated by overlapping materials. In this thesis the image noise of different materials are evaluated by experimental measurements. A method for evaluating an overall error in justify; LINE-HEIGHT: 15pt; TEXT-INDENT: 17.85pt; MARGIN: 0in 0in 0pt; unicode-bidi: embed; DIRECTION: ltr; mso-line-height-rule: exactly" In the following, these material categories are shown with various colors in the x-ray image. Based on this, in baggage iection, organic material category is orange, light metals category is green and heavy metals category is blue. Colors are selected similar in points in which the error is high in order to cause less artifact productions by errors in material identifications. Also several image enhancement techniques are used in order to human user be able to recognize details inside baggage or vehicle better. X-ray images in these applications have a non-uniform illumination. In order to correct this non-uniform illumination, empty spaces around objects are detected and amounts of non-uniform illuminations are calculated by averaging empty spaces, and non-uniform illumination in image is corrected by them. Finally, a method for implementing mentioned algorithms by FPGAs is proposed. In this method using Local-Area-Network the image and the Look-Up-Table are transmitted from a PC to FPGA, and the processed image is returned from FPGA to PC. Keywords: Dual-energy x-ray imaging, Material Discrimination, Discrimination ability, Security iection.
