Partial Image Encryption Based on Using Discrete Cosine Transform Coefficients and Lightweight Stream Algorithm

2019 ◽  
Vol 16 (4) ◽  
pp. 1573-1576
Author(s):  
M Sundararajan ◽  
M Veerappan ◽  
S Anbazhagan
Keyword(s):  
Discrete Cosine Transform ◽  
Image Encryption ◽  
Cosine Transform ◽  
Transform Coefficients

scholarly journals Improved Algorithm for ODCT Computation of a Running Data Sequence

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
S. Akhter ◽  
V. Karwal ◽  
R. C. Jain
Keyword(s):  
Real Time ◽  
Discrete Cosine Transform ◽  
Input Data ◽  
Time Sequence ◽  
Data Sequence ◽  
Cosine Transform ◽  
Rectangular Window ◽  
Sine Transform ◽  
Data Points ◽  
Transform Coefficients

Fast windowed update algorithms capable of independently updating the odd discrete cosine transform (ODCT) and odd discrete sine transform (ODST) of a running data sequence are analytically developed. In this algorithm, to compute the ODCT coefficients of a real-time sequence, we do not require the ODST coefficients. Similarly, the ODST coefficients of the shifted sequence can be calculated without using ODCT coefficients. The running input data sequence is sampled using a rectangular window. However, this idea can be easily extended for other windows. The update algorithm derived herein can be used to compute the transform coefficients of the shifted sequence as new data points are available. The complexity of developed algorithm isO(N). The validity of algorithm is tested by MATLAB simulations.

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