Geometric Correction in Recent High Resolution Satellite Imagery: A Case Study in Coimbatore, Tamil Nadu

Abstract

This paper proposes a new data-hiding method basedon pixel pair matching (PPM). The basic idea of PPM is to usethe values of pixel pair as a reference coordinate, and search acoordinate in the neighborhood set of this pixel pair according to agivenmessage digit. The pixel pair is then replaced by the searchedcoordinate to conceal the digit. Exploiting modification direction(EMD) and diamond encoding (DE) are two data-hiding methodsproposed recently based on PPM. The maximum capacity of EMDis 1.161 bpp and DE extends the payload of EMD by embeddingdigits in a larger notational system. The proposed method offerslower distortion than DE by providing more compact neighborhoodsets and allowing embedded digits in any notational system.Compared with the optimal pixel adjustment process (OPAP)method, the proposed method always has lower distortion forvarious payloads. Experimental results reveal that the proposedmethod not only provides better performance than those of OPAPand DE, but also is secure under the detection of some well-knownsteganalysis techniques.

Data flow Diagram:

Existing System:

A simple and efficient optimal pixel adjustment process (OPAP) method to reduce the distortion caused by LSB replacement. In their method, if message bits are embedded into the right-most LSBs of a bit pixel, other bits are adjusted by a simple evaluation. Namely, if the adjusted result offers a smaller distortion, these bits are either replaced by the adjusted result or otherwise kept un-modified. The LSB and OPAP methods employ one pixel as an embedding unit, and conceal data into the right-most LSBs.

Proposed System:

Exploiting modification direction(EMD) and diamond encoding (DE) are two data-hiding methodsproposed recently based on PPM. The maximum capacity of EMDis 1.161 bpp and DE extends the payload of EMD by embedding digits in a larger notational system. The proposed method offerslower distortion than DE by providing more compact neighborhoodsets and allowing embedded digits in any notational system.Compared with the optimal pixel adjustment process (OPAP)method, the proposed method always has lower distortion forvarious payloads.

Modules:

  1. Login modules.
  2. Adaptive pixel pair matching (APPM) module.
  3. Embedding Procedure module.
  4. Extraction Procedure Module.

Module Description:

1.Login modules.

Login or logon (also called logging in or on and signing in or on) is the process by which individual access to a computer system is controlled by identification of the user using credentials provided by the user.

A user can log in to a system and can then log out or log off (perform a logout / logoff) when the access is no longer needed.Logging out may be done explicitly by the user performing some action, such as entering the appropriate command, or clicking a website link labeled as such. It can also be done implicitly, such as by powering the machine off, closing a web browser window, leaving a website, or not refreshing a webpage within a defined period.

2.Adaptive pixel pair matching (APPM) module

Data-hiding method based on PPM. DE greatly enhancesthe payload of EMD while preserving acceptable stegoimage quality. However, there are several problems. First, thepayload of DE is determined by the selected notational system, two pixels are scanned as an embeddingunit and a specially designed neighborhood set is employed toembed message digits with a smallest notational system. APPMallows users to select digits in any notational system for data embedding,and thus achieves a better image quality.

3.Embedding Procedure module.

Suppose the cover image is of size M x M, S is the messagebits to be concealed and the size of is B. First we calculatethe minimum such that all the message bits can be embedded.Then, message digits are sequentially concealed into pairs ofpixels. Suppose a cover image of size 512 512 with embeddingrequirement of 520 000 bits.

4.Extraction Procedure Module.

To extract the embedded message digits, pixel pairs arescanned in the same order as in the embedding procedure. Theembedded message digits are the values of extraction functionof the scanned pixel pairs.

Hardware Requirements:

•System: Pentium IV 2.4 GHz.

•Hard Disk: 40 GB.

•Floppy Drive: 1.44 Mb.

•Monitor: 15 VGA Colour.

•Mouse: Logitech.

•Ram: 256 Mb.

Software Requirements:

•Operating system : - Windows XP Professional.

•Front End : - Visual Studio.Net 2005

•Coding Language: - Visual C# .Net.