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1 Software development for protecting printed documents Maria Nazarkevych1,Yurii Klishch2,Roman Oliyarnik1 1Department of Information Technology Publishing 2 Automated Control Systems Department, Lviv Polytechnic National University, S. Bandery Str., 12, Lviv, 79013, UKRAINE, E -mail: [email protected] Developed software protects printed documents. Protection is based on modifying the bitmap and converting it into a grid which changes by offset, amplitude or width. Also this software can protect documents of strict accountability. Keywords: computer science, security printing, image. image and turn into distorted sine wave with varying amplitude oscillations. It is also possible thickening of the lines in the ground overlay it on the image. Method of thickness variation This method the use grid of lines that represents grayscale using changing its thickness (Fig. 2). The line is constructed from the base and shifted curves. I. Introduction One of the types of graphical method for protecting printed products is micrographics. Protection is based on effect of the latent image of high resolution lines. Visually, the micrographics perceived as a solid line, although composed of strokes, which can be seen only with a significant increase. As a security element in image processing is widely used protective grids repetitive. These elements form Periodic and Aperiodic protective nets. In forming an image field of security as aperiodic grill level anticounterfeiting security is much higher than with conventional periodic grill. Scheme of the program (for the formation of protection) depicted in Fig. 1 and shows the main functional parts protection. Software are given an input image, settings and parameters of a single line. Fig. 2. Example of the method changes the line thickness Fig. 1. Block diagram of image protection Software converts input image it to size for printing. According to the parameters of a single line formed by the grid lines, which, in conjunction with the parameters forms protection. At the output we get protected raster or vector image. II. Methods of protection Software implements three different methods of formation protection. Depending on the selected method, the line can be as simple shift in the overlay Base curve is the graph of the sine of parameters such as wave frequency and amplitude. It is the same for all lines and calculated by the formula: Sin (ay * mlt) * wid, where wid - amplitude curve, mlt - period of the wave. Settings can be changed in the menu. Shifted curve is constructed from the basic curve offset. The shift is different for each point of the original image. Calculated by the formula: Sin (ay * mlt) * wid + cf, where cf - displacement ratio. Ratio of displacement depends on the input grayscale image. Since the input image can be colored, each pixel is converted to grayscale and then used to calculate the coefficient of displacement. Bias factor is calculated by the formula: (256 - pxl) / mult, where pxl - Grayscale (accepts values from 0 to 255), mult - conversion factor (allows you to specify a smooth transfer gradients). "COMPUTER SCIENCE & INFORMATION TECHNOLOGIES" (CSIT'2014), 18-22 NOVEMBER 2014, LVIV, UKRAINE 2 After building the base and shifted curves, they form a closed broken, the inner side of which is filled with black. Method of biasing This method allows you to protect images using edge detection. It is best suited for contrasting pictures, images containing text, logos - Fig. 3. The line is based on the sine function and uses the same parameters as the method of changing thickness. Fig. 2.6. Example of gradient representation Fig. 3. Example images protected by the bias Contour is line that defines shape of object. To separate contour, line in a high contrast point shifts, which allows you to visually see outline of the object. Level of bias depends on the difference of gray levels of neighboring pixels in the input image (Fig. 4). Fig. 4. Example of edge detection in place of high contrast The feature of this method is that the gradation of gray input image is not represented that allows enhance protection of bright images. The method of amplitude variation Representation of shades of gray in this method occurs via changing the amplitude of trigonometric function sine: Sin (ay * mlt) * wid * cf, where wid - basic amplitude curve, mlt - period of the wave, cf - magnification factor. The basic amplitude is set so that the curve looked like a sine wave in the representation of white. Rate of increase of the amplitude calculated by the formula (2.3) and allows you to smoothly change the grayscale on the protected images, which improves representation gradient, as shown in Fig. 2.6. Formation grid Algorithm of grid formation provides high performance resources and universality of input images. To construct the grid input image discredited according to the size of the print size via bilinear interpolation method by which pixels are added by averaging the color values of surrounding pixels. This interpolation method is optimal in the ratio of the speed/quality. In result we have an image that matches the size of the output and is the source for building the lines. Then, based on the discredited image is formed array of converted to grayscale pixels. According to the parameters forming grid. Parameters of grid formation include the density of lines (the number of vertical lines of original image on a line of protected images), the size of print image and a method of protection. Formed grid is later used to display lines on vector or raster image. The lines are smoothed using Bezier curves, avoiding angles in vector images. Saving Protected image can be saved as a raster or as a vector image. Saving vector image occurs in EMF (Eng. Enhanced Metafile). EMF is a universal format of vector graphic files for applications Windows. Conclusion Developed software protects printed documents. Software based on the input image size converts it into print. According to the parameters of a single line formed by the grid lines, which, in conjunction with the parameters forms protection. At the output we get protected raster or vector image. References [1] Nazarkevych MA Methods for improving the efficiency of printing facilities Ateb-protection functions. Nazarkevych MA Monograph. Lviv: Lviv Polytechnic National University PublishingHouse,2011. 188 pp. "COMPUTER SCIENCE & INFORMATION TECHNOLOGIES" (CSIT'2014), 18-22 NOVEMBER 2014, LVIV, UKRAINE 3 "COMPUTER SCIENCE & INFORMATION TECHNOLOGIES" (CSIT'2014), 18-22 NOVEMBER 2014, LVIV, UKRAINE