on a tripod 2.5m away from a 24-inch LCD screen
Dell, 2405FPW. Two scenarios are used for testing:
Recording 1: The recorded videos are resized to orig-
inal size and recompressed by Xvid, 1000 Kbit per
second. Recording 2: The recorded videos are re-
sized to original size and recompressed by Xvid, 500
Kbit per second. Asikuzzaman et al. (Md. Asikuz-
zaman and Pickering, 2014) propose a blind video
watermarking algorithm where the watermark is em-
bedded into both chrominance channels using a dual-
tree complex wavelet transform. This algorithm is
robust to downscaling in arbitrary resolution, aspect
ratio change, compression, and Camcording. The ro-
bustness against Camcording was tested by display-
ing watermarked video sequences at the rate of 25
fps and 30 fps on a 24-inch Samsung monitor and
recorded the content with an iPhone 4S. Li et al.
(Li Li, 2015) proposes an H.264/AVC HDTV water-
marking method that is robust to camcorder record-
ing, transcoding, recoding, and other geometric at-
tacks. They test the robustness against camcorder at-
tack by recording the watermarked video using a cam-
corder Sony HXR-MC1500C on a tripod 2 m away
from a 24 in. LCD monitor.
2.3 Review of Camcording Simulators
Most of robustness tests against Camcording attack
are carried out on a single screen model, using a sin-
gle capture model and applying, generally, only one
scenario of equipment’s disposition. In fact, bench-
marking of the camcorder path is far from being a
frequent practice today due to the heavy logistical ob-
stacles associated with this evaluation process. To
solve this problem, some researchers are now focus-
ing on the study of the impacts and distortions caused
by the Camcording with the aim of designing pre-
cise simulators for this attack. In addition, the re-
sults of this study and analysis could be reused to im-
prove video watermarking techniques. This process
has been adopted in some previous works to model the
printing and scanning process of still-image water-
marking and the acoustic path transmission but Cam-
cording is relatively not enough studied compared
to this works focusing only on spatial deformations.
Owing to the interaction between several devices, the
displayed content of the camcorder changes video in
some various ways, including temporal transforma-
tions, geometric distortions, variable and non-uniform
luminance transformations, alteration colors satura-
tion... It is necessary to understand the different phe-
nomena involved to design effective and precise sim-
ulators that imitate these effects.
Ben Zid et al. (Cherif Ben Zid and Doerr, 2013)
have study the luminance transforms due to the Cam-
cording process and investigate three different alter-
ations which are the spatial non-uniformity, the steady
state luminance response, and the transient luminance
response. To do this, they performed several con-
trolled experiments where they simulated different
configurations of the Camcording process. They used
two alternative displays and one camcorder device
which are a 24 ”LCD monitor Dell U241014, a home
theater video projector, Christie HD5Kc15 and a Sony
HDR-CX200ETM camcorder. They then excited the
system with several visual stimuli and looked at the
recorded answers to infer the underlying mechanisms
that take place as well as their characteristics. This
study can be improved because it is focused on only
three distortions that video content undergoes along
Camcording process and uses only two displays and
one capturing device.
Hajj-Ahmad et al. (Adi Hajj-Ahmad and Wu,
2017) have lead an investigation of the lumi-
nance flicker that is naturally present in camcorded
recordings due to the interplay between liquid-
crystaldisplay (LCD) screen and camcorder. To do
this, they have break down the acquisition pipeline
into three stages which are the emission of a back-
light signal by the screen, the integration of the light
emitted by the screen with a sensor of the camcorder,
and the sequential sampling of the different rows of
a video frame. They initially model the flicker signal
and demonstrate that its parameters are related to such
internal characteristics of the capture devices as the
back-light frequency of the LCD screen and the read-
out time of the camcorder. Then, they introduce an
estimation strategy to recuperate these hidden param-
eters directly from camcorded recordings and demon-
strate that such forensic cues could provide intelli-
gence on the pirate devices. They additionally dis-
cuss on how to recuperate the shape of the low power
flicker signal and demonstrate that it could be used to
infer which back-light technology employed in the pi-
rate LCD screen. The authors set out the prospects to
better understand the applicability of flicker forensics
which will involve large scale validation experiments
with a wide diversity of devices, hence the utility of
our proposed dataset.
The most complete simulator that is already avail-
able as open source tool to researchers is the Cam-
Mark developed by Schaber et al. (P. Schaber, 2014).
This tool simulates a re-acquisition of a video from
a camcorder to support watermarking development
by enabling automated test cases for such camcorder
copy attacks (fig 1). The authors are thus trying to
simulate the typical artifacts of a camcorder captur-
ing: geometric modifications (aspect ratio changes,
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