Download Software development for protecting printed documents

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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
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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
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"COMPUTER SCIENCE & INFORMATION TECHNOLOGIES" (CSIT'2014), 18-22 NOVEMBER 2014, LVIV, UKRAINE