Cryptography Reference
In-Depth Information
1-high and low were 28 and 80 in Red color, respectively. Other colors were
quite similar. It is obvious that JPG-1-high has a finer difference pattern
than JPG-1-low case. The embedding times are shown in Table 8.9.
Table 8.9.
Before and after embedding comparison.
JPG file name
JPG-1-high.jpg JPG-1-low.jpg JPG-2-high.jpg JPG-2-low.jpg
File size (Before) (KB)
482
99
176
46
File size (After) (KB)
437
78
152
30
Embedding Ratio
0.10
0.12
0.11
0.10
Embedding time (approx)
0.4 sec
0.1 sec
0.1 sec
0.1 sec
(A) Image difference in Red color
(B) Image difference in Red color
(JPG-1-high)
(JPG-1-lowf)
Fig. 8.23.
Image difference patterns between before and after JPEG embedding in
Red color component.
Extracting
The extracting operation was very smooth. All embedded data, i.e., bare text
files, were extracted exactly. The extraction times are listed in Table 8.10.
Table 8.10.
Extraction time.
JPG file name
JPG-1-high.jpg JPG-1-low.jpg JPG-2-high.jpg JPG-2-low.jpg
Extraction time (approx)
0.6 sec
0.2 sec
0.3 sec
0.1 sec
