The format of information is changing with the developments of computer methods and formats. Graphical information can be also used to transfer text. In this paper, I am going to describe the new approach via merged text implemented directly to the image by using alpha channel of the pictures. This kind of encryption can be also used as the opportunity to spread script guidelines, which subsequently enable assuming control of entire computer. The paper presents a discussion and experimental set up of the designed solution.
Nowadays information processing is possible in
various diferent levels. We can find many systems which
proceed information from users to get the knowledge
about several aspects. One of the most popular
information format is an image. We can have photos from
holidays, work, travel or many other occasions. This
type of information is easy to read and possible to use Figure 1: Sample merge scheme when the text code is
simin various devices. From images we can have informa- ply inserted into the image by third program to compose an
tion about objects visible there by analyzing pixels of output file.
the image or simply all color channels. In [
Other field of working with the information hidden and bad way. The idea presented in this paper is to use
in images is steganography. This field of computer an alpha channel, which is responsible for the
resoluscience is oriented on developments of algorithms for tion level - the diference between the value of 255 and
transferring some hidden information in images. In 254 is imperceptible without special program. The HD
[
Transmitter Transmitter is the program that codes guidelines for the receiver, downloads picture and links text file from proper folders and checks whether the pictures have correct format. If not, the program would turn it into the demanded one. Sample scheme is visible in Fig. 1. Afterwards, the predefined statement is encoded, whereby program has already determined format and ending of the instruction. Therefore it is not necessary for the receiver to analyse entire picture to indicate the guideline.
Receiver The program is receiving instructions, first checks if the folder name is “downloaded”. Then the history of files is constructed with proper format in order to prevent conducting the same instruction. The system script is getting overwritten by meaningless writing and consecutively deleted, so it would not be possible to regain it. After carrying the instructions out the program overwrites the picture by the new one, which does not contain any guidelines. Sample scheme is visible in Fig. 3. Of course, it is possible to adjust the program in a way that enables it to turn itself from receiver into the transmitter and to encode new instructions for every file with proper format. This type of the structure is also often used in viruses since it can infect solely one computer in the inner network, because it will spread virus to each system that receives graphical information from attacked computer, and thus the whole network can be infected easily, at the short period of time.
The system result from input to the output is presented in Fig. 2. On the entire process an information is merged with the initial input to compose a final output. On the way an alpha channel is used to fit within the text format information.
In regard to restricted transcript place, it benefits to use certain an approach for data compression. In program, for instance, the Shannon-Fano coding is used through its easy implementation and satisfying level of compression. The Shannon-Fano coding is a type of lossless compression - it finds prefix code for each discreet source.
Example. a) S={a,b,c,d} b) p={0.6,0.2,0.15,0.05} For the sequence a) which corresponds to the probability, i.e. the number of occurrence in the text is coded to the number of all digits b). The situation is visible in Fig. 5. The program is checking itself whether the implementation if dictionary at the beginning of coding would take less time than the message. Thereby, the program optimally exploits place in picture.
for regular computer user. The real intent of a message can be therefore easily hidden due to innovative method. Let us now think how to use the above system for this. The first pixels of a graphic are changed into the desirable file-format, which entails that the receiver itself can on an going basis decode messages 2.3. Composed Model of Image Data conveyed by its download. The same approach can be Encoding applied to text files. To enable it, the program firstly changes given file into binary system pattern. The The picture itself contains much more information than scheme requires to use adequate amount of pictures simple text, so one should label which starting format to code the message. The receiver, after getting an in- is expected. There are three options, hence, it is necformation turns it into the desirable format. essary to decrease the amount of data in the picture.
The color accuracy relies on the diferences between particular colors. It means that value assigned to color does not belong already to the interval (0,255), but instead is one of the lower power of 2, determined by the user. Thereby, once the graphics is decoded, the reduction of pixels will go ahead, which is formed from the formula
= log2 The interval size is a power of 2, due to the writing ongoing in binary form, so that is is possible to use the whole length of bites
(1) ( ) = ∗ 28− (2) high loss of the details. The maximum polling is used, the blurs phenomena takes place, and thereby the picture loses its sharp edges - and ultimately, everything is mixed together.
In opposite, using the minimum polling reflects in the enhancing the image noises, whereby the transparency undergoes decrease. Thus, is is highly significant to adjust properly polling to picture. Sample schemes of both ways is visible in Fig. 6, while the resulting quality of processing is visible in Fig. 7.
The amount of colours is crucial through each new one is adding another dimension to the picture, that has been already scaled-down. Thereby quantity of photos being required for sending solely one photo is greatly enlarged, i.e. it is possible to establish diversiifed options of recreating the colour either by using the RGB’s values or in the Grayscale, which would save the place. The changes of colour channels for the input image are visible in Fig. 8.
Whereas x is value of the pixel and r is square root of the interval size. Sample results from pixels encoding is presented in Fig. 4. In order to not complicate both, coder and decoder, the transition takes place in a dis- 3. Conclusions tinct program, which also allows the independent action of a program. It is worth stressing, that the coder There are plenty of risks that occur while one is usis adjusted to binary data even though the pixel has ing an internet, hence, we do not want our private spectrum 256 and still operates at maximum values. information to get into others control. That is why, The diference must be as little as it is possible due to the developed scheme for quiet conveying instructions security matter - indeed, once somebody knows the for other computer or sending the graphics and text communication pattern, the entire scheme is not ade- messages is an important to be considered in common quate anymore. information-protection manners. Moreover, the pa
The precision of colors projection relies on the sim- per points out the possible, sensible protection of anplification of the graphics by using polling method. tivirus systems. It is important to notice that the sendThe picture is converted as scantily as possible due to ing graphics process is problematic action, however, under certain circumstances it seems to be only available approach for sending sensible information-media graphics, for instance under high censorship conditions. The idea will be continuously developed toward optimal encoding. I do believe it is the most optimal approach in case of protecting the data.