Data Hiding Techniques In Digital Images
With literally millions of images moving on the Internet each year it is safe to say that hiding data in digital image is of real concern to many in the security field. Therefore how to protect secret messages during transmission becomes an important issue. Hiding data provides a good layer of pr...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English English |
| Published: |
2003
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/12218/1/FK_2003_56.pdf http://psasir.upm.edu.my/id/eprint/12218/ |
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| Summary: | With literally millions of images moving on the Internet each year it is safe to
say that hiding data in digital image is of real concern to many in the security field.
Therefore how to protect secret messages during transmission becomes an important
issue. Hiding data provides a good layer of protection on the secret message, so the
purpose of this thesis is to study the data hiding techniques in digital images as a new
and powerful technology capable of solving important practical problems.
Depending on what information in which form is hidden in the digital images,
one can distinguish two types of data hiding techniques, spatial domain techniques, and
frequency domain techniques.
In the spatial domain techniques, a digital image serves as a carrier for a secret
message. For instance, by replacing the least significant bit of each pixel in the carrier
image with the secret message after changing it to stream of bits, the changes to the
carrier image will be imperceptible and the secret message will be masked by carrier image. In this side, two programs had been implemented using MATLAB program to
illustrate the main idea involved in least significant technique (low bit encoding), and
the other to illustrate the masking technique inside the carrier image.
In the frequency domain techniques, a short message is embedded in the carrier
image in a robust algorithm. Robustness means the ability to survive common image
processing operations, such as lossy compression, filtering, noise adding, geometrical
transformations, etc. So in this technique two programs had been implemented to
illustrate the main idea involved in frequency domain, one with the Fast Fourier
Transform (FFT), and the other with the Discrete Wavelet Transform (DWT).
After all these studies, one of the algorithms in the masking technique is
developed and implemented using JAVA program to embed message into true color
image with a good quality and higher capacity. Beside that the carrier images in different
techniques were examined by exposing them to common signal processing operations
such as image resizing, rotation, histogram equalization, lossy Compression, and
Gaussian noise addition to illustrate the characteristic of the data hiding techniques, such
as hiding capacity, robustness, undetectability, and perceptual transparency
Finally, it has been shown that the frequency transformation techniques are more
robust, and hence suitable for water marking and data hiding purpose. The spatial
domain techniques exhibit loss robustness but due to its higher capacity and good quality
are perfect for data hiding purposes. |
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