Multiple-target recognition using the discrete rotational Fourier transform

Neng-Chung Hu; Kuo-Kan Yu; Hong-I Chang

doi:10.1117/1.1386371

1 August 2001 Multiple-target recognition using the discrete rotational Fourier transform

Neng-Chung Hu, Kuo-Kan Yu, Hong-I Chang

Optical Engineering, Vol. 40, Issue 8, (August 2001). https://doi.org/10.1117/1.1386371

Much research has been devoted to locating multiple targets on the condition that there is only one pattern in the reference image and more than one such pattern in the input image. We, however, propose a new correlator to locate and display multiple different targets when both the reference and the input images contain many different patterns. This correlator is based on the two-dimensional (2-D) discrete rotational Fourier transform (DRFT), which extends the one-dimensional (1-D) DRFT. Since the DRFT domain of an image contains information both in the spatial domain and in the frequency domain of the image, we use this property to locate and display the matched targets. The DRFT-based correlator first obtains x?[u1,u2]H*?[u1,u2],where x?[u1,u2] and x?[u1,u2] are the DRFTs of the input image and the reference image, respectively; then the inverse discrete Fourier transform (IDFT) of x?[u1,u2]H*?[u1,u2], yields many cone-shaped correlation peaks. A correlation peak stands for a matched pattern between the input image and the reference image. To display the shape of the matched pattern, x?[u1,u2] is shifted according to the position of the correlation peak yielding x?[u1,u2]. Finally, |x?[u1,u2]H*?[u1,u2]| displays the shape of the matched pattern. Like the conventional correlator, the DRFT-based correlator can recognize only the translated versions of the patterns in reference image. The purpose of this approach is to recognize multiple different targets simultaneously. The properties of the proposed 2-D DRFT are also presented.

©(2001) Society of Photo-Optical Instrumentation Engineers (SPIE)

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Neng-Chung Hu, Kuo-Kan Yu, and Hong-I Chang "Multiple-target recognition using the discrete rotational Fourier transform," Optical Engineering 40(8), (1 August 2001). https://doi.org/10.1117/1.1386371

Published: 1 August 2001

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