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Extracting Barcodes from a
Camera-Shaken Image on
Camera Phones
Graduate Institute of Communication
Engineering
National Taiwan University
Chung-Hua Chu, De-Nian Yang and Ming-Syan
Chen
報告者 : M97G0225 黃庭筠
OUTLINE
• INTRODUCTION
• BARCODE EXTRACTION ALGORITHM
• EXPERIMENTAL RESULTS
• CONCLUSION
INTRODUCTION
• problem is to extract and restore the
barcode to improve the correctness of the
recognition.
• Extracting Camera-Shaken Barcode
(ECSB) algorithm for the problem
BARCODE EXTRACTION
ALGORITHM
Barcode area extraction
ECSB first uses Edge Detection to detect the rough
barcode area as depicted.
Then, ECSB dilates the edge-detected image with
two directions (i.e., vertical and horizontal) such
that we can obtain the precise barcode area as
shown.
Barcode Restoration
Use a large constant c to approximate an
unknown parameter SNR (Signal to Noise
Ratio), where c is larger than or equal to
the height of the distorted image.
Barcode Restoration
Barcode Restoration
g(i, j) = f(i, j) * h(i, j) + n(i, j)
g(i, j) : presented by a linear system of a convolution
f (i, j) : denotes the original image
n(i, j) : defined as a Gaussian white noise with zero mean
h(i, j) : (PSF) can be viewed as the filter caused by the
shake
Barcode Restoration
N : denotes the length of the camera motion
Θ: denotes the direction of the camera motion
Camera-Shaken Direction and
Length Estimation
•
estimate the camera-shaken direction Θ :
1. first transform the camera-shaken image to a
Cepstrum-domain image C (i, j)
C (i, j) : Inverse Fourier transform of log(1 + G (i, j) )
G (i, j) : is the Fourier transform of g (i, j)
2. use Hough transform to find out the camera-shaken
direction Θ in C (i, j)
Camera-Shaken Direction and
Length Estimation
• camera-shaken length N :
1. calculate the average of all pixels in C' (i, j)
2. Finally, we calculate the first zero crossing where the
camera-shaken length N
Camera-Shaken Direction and
Length Estimation
Camera Shake Restoration
Use Wiener filter to determine the solution F (i, j)
Sf : power spectrum of the original image
Sn : power spectrum of the noise
H (i, j) : frequency domain of h (i , j)
H*(i, j) : complex conjugate of H (i, j)
∣ H (i, j)∣^2 : H*(i, j) H(i, j)
EXPERIMENTAL RESULTS
EXPERIMENTAL RESULTS
• Tag Richardson Lucy method (TRL) :
Uses tag-based identification to extract QR code,
and then Richardson Lucy method (RL) to restore
the extracted QR code.
EXPERIMENTAL RESULTS
• root mean-square error (RMSE)
H : height of f (i, j)
W : width of f (i, j)
EXPERIMENTAL RESULTS
CONCLUSION
• In this paper, we proposed an efficient algorithm
to extract the 2D barcodes in a camera-shaken
image.
• The experimental results have showed that our
approach is not only of smaller running time but
of higher accuracy of the barcode recognition in
a mobile information environment.