DWM, Digital Watermarking, Digital Watermark
DWT, Discrete Wavelet Transform
DCT, Discrete Cosine Transform
Digital Image processing
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Digital Watermarking (DWM) is a technique of protecting digital data. This code base implements 2 methods for marking digital images based on Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT).
Several attacks (signal degradations such as noise, dithering, filtering, cropping, lossy JPEG compression) on marked image were conducted. Attacked images are saved and the watermark is extracted.
Robustness of DWT vs DCT is graded based on the quality of extracted watermark. The measure used is the Correlation coefficient (0-100% or 0-1).
See Main.mlx example file for simple Image Watermarking Procedure to control the program flow. It does not contain popup windows for selections, instead it has drop down selections.
Procedure steps are separated by sections that match the steps of the main menu in Main.m.
Also, hardcoded input variables from Main.m are clearly marked in Main.mlx as numeric sliders.
>> 
>> 
Not marked. Watermark method: None.
Attack: None
C:\Users\dzoni\Documents\GitHub\watermark\output\marked\Marked_image_None.tif
Not detected. Watermark method: None.
Correlation Coefficient of the watermarks NaN
Normalized Correlation of the watermarks 0.000000
Correlation Coefficient of the images 1.000000
Normalized Correlation of the images 1.000000
Num of bit errors in detected watermark 2635
BER [%] for detected watermark 64.331055
*******************************************************
Method: DCT
Attack: None
C:\Users\dzoni\Documents\GitHub\watermark\output\marked\Marked_image_DCT.tif
Correlation Coefficient of the watermarks 0.995758
Normalized Correlation of the watermarks 0.996964
Correlation Coefficient of the images 0.999543
Normalized Correlation of the images 0.999996
Num of bit errors in detected watermark 8
BER [%] for detected watermark 0.195313
*******************************************************
Method: DWT
Attack: None
C:\Users\dzoni\Documents\GitHub\watermark\output\marked\Marked_image_DWT.tif
Correlation Coefficient of the watermarks 1.000000
Normalized Correlation of the watermarks 1.000000
Correlation Coefficient of the images 0.998351
Normalized Correlation of the images 1.000107
Num of bit errors in detected watermark 0
BER [%] for detected watermark 0.000000
*******************************************************
Nikola Jovanovic on ResearchGate
Digital Watermarking – Comparison of DCT and DWT methods, ResearchGate
Digital Watermarking in Wavelet domain – Comparison of different types of wavelets, ResearchGate
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