resolution reconstruction, the other is the deep
learning-based face detection.
Generally speaking, the super resolution
construction are some kinds of restoration
techniques, which consists frequency domain
algorithm and time domain algorithm, for the
original high resolution image based on multi-frame
low resolution images (Zhang, 2010). All the low
resolution images is captured in the same scene with
the original high resolution image and there just
exists slight changes. If there only exists one low
resolution, the ordinary method to get the high
resolution image is interpolation.
In the case of only one low resolution image,
different form the traditional interpolation method,
in (Luo, 2011) the authors proposed the deep
learning-based strategy for single image super-
resolution. With light weighted structure deep
convolution neural network (CNN), this method
directed learns an end-to-end mapping between the
low/high resolution images. They also proved that
the sparse-coding-based SR can be viewed as a
convolutional neural network. This work claimed the
state-of-the-art performance and suitable for the
online usage.
Figure 4: Given a low resolution image Y, the first
convolution layer extracts a set of feature maps. The
second layer maps these feature maps nonlinearly to high
resolution patch representation. The last layer combines
the predictions with a spatial neighbourhood to produce
the final high resolution image F(Y).
In this above-mentioned work, the authors took
the low resolution image as the input and output the
high resolution one. To execute the image quality
enhancement using this deep-learning-based method,
the training stage should be carried out prior to the
output stage. Refer to this method, we utilize over
5000 pairs of LR images and HR images, which
with 126*102 pixels and 441*358 pixels
respectively, as training dataset.
Fig.4 shows the schematic diagram of the deep
learning-based SR.
Face detection in the complex scenes is an
essential but rarely rough task. To the fixed
surveillance camera, the field of view (FOV) is
constant. In this scene, the face region in the frame
image is enough bit to execute the face detection.
But in the ordinary surveillance scenes, to those
peoples far away from the fixed-focus camera, the
face region maybe too small to be detected. In this
case, the pedestrian detection should be utilized to
detect the concerned people and track this people
until his approach makes the face region enough big
to be detected. This strategy was proposed in our
previous work (Yan, 2014) and proved to be
effective and efficient.
Considering the complexity of face detection in
the ordinary surveillance scenes, the researchers
presents a new state-of-the art approach in (Chen,
2014). They observed that the aligned face shapes
provides better features for face classification. To
combine the face alignment and detection more
effectively, they learned this two tasks in the same
cascade. By exploiting the joint learning, the
capability of cascade detection and real time
performance can both achieve the satisfied status.
Figure 5: The key point annotation on face shape.
As shown in Fig.5, we use 38 key points to
describe the face shape, 10 points for face contour, 6
points for eyebrows, 10 points for eyes, 7 points for
nose and 5 points for lip respectively.
We bought a face image dataset consisted of
about 20, 000 face images and 20, 000 natural scene
images without faces from web. All face images are
transferred into grayscale images. After all the face
images are labelled, the dataset is utilized to train the
classification/regression tree.
3 EXPERIMENT AND
CONCLUSION
We utilized the combination of the on-site
surveillance camera and RFID reader to realize the
self-service passenger pass. The key techniques
focus in the on-site face detection effectively and the
online SR reconstruction for the low resolution ID
electronic photos. As a comparison, we also directly
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