KEYWORDS: 3D modeling, 3D image processing, Object recognition, 3D acquisition, Image filtering, Distortion, Databases, Raster graphics, Image quality, 3D applications
Paper presents study results of MINACE filter implementation to recognition problem of object subjected to out-of-plane rotation distortion and captured as raster image. Filter training conducted by images acquired from synthetic 3D object model. Dependence of recognition results from 3D model illumination type is shown.
We address the recognition problem of grayscale images of object subjected to out-of-plane rotation distortion. We compare filter realization as computer generated hologram and filter projection on modulator domain. Our study results of the filter discriminating characteristic analysis are shown. The results of the filter implementation modeling in 4-f correlator and the initial experimental result are represented.
Minimum Noise And Correlation Energy (MINACE) filters application provides good ability to recognize in case of grayscale input images of an object with background noises. For fast correlation matching MINACE filters can be used in 4-f correlators as a computer generated hologram (holographic filters). In this paper different variants of holographic filters realization were discussed. The results of correlation recognition with holographic MINACE filters are presented.
Security holograms (SH) are perspective for document and product authenticity protection due to difficulties of
such a protection mark falsification. Mass production of SH uses widespread technology of hot foil or lavsan
paper stamping. The quality of holograms significantly depends on perfection of nickel master-matrix that is
used in stamping equipment. We represent the method of automatic quality inspection of nickel master-matrix
based on digital processing of its surface relief microphotographs. Proposed processing algorithm is based on
combination of image spatial frequency analysis and image matching using distortion invariant correlation filters.
The results of our method application for real SH master-matrices inspection are shown in this paper.
Optical correlators are well known to be perspective for real time image recognition. Application of distortion invariant filters (DIF) provides image recognition with increased speed of correlation image matching. Minimum noise and correlation energy filters (MINACE filters) provide good recognition in the case of gray-scale input images. These filters possess a good mathematical basis and can be efficiently implemented in digital processing systems or in hybrid opto-digital correlators at a high rate. This paper is subjected to synthesis and realization of MINACE filters for 4-f correlator as computer generated holograms (holographic filters).
Application of distortion invariant filters (DIF) provides the possibility of invariant image recognition with
increased speed of correlation matching. DIF with the minimization of correlation energy enable to control the
properties of output correlation signal due to the parameterization during its synthesis. There are several types
of such a filters presented nowadays. The relevance degree of each type of filter application is determined by the
specific conditions of the recognition task. Thus it requires a comparative analysis of the filters performance.
The simulations were provided for the DIF of the following types: MACE (Minimum Average Correlation
Energy Filter), GMACE (Gaussian-minimum average correlation energy filters), MINACE (Minimum noise and
correlation energy filter) and WMACE (the version of GMACE where the smoothing function is the wavelet).
The synthesis of filters was carried out under identical conditions of gray-scale image recognition problem (out
of plane rotated objects). The comparison results of discrimination characteristics and the requirements of DIFs
synthesis are described and discussed.
Realization of distortion invariant correlation filters in optical image correlators open possibilities for object identification with remarkably high computational capabilities. Application of the linear phase coefficient composite filter (LPCCF) is attractive for recognition of binary edged images. We use methods of digital holographic synthesis to realize LPCCF in a coherent 4-F correlator as a computer-generated amplitude holographic filter. A high resolution spatial light modulator (SLM) has to be implemented for such a filter representation. Transparency limitations of high frame rate and high resolution SLM's and its effect on recognition performance of holographic filter in the 4-F correlator are discussed in the given paper.
Invariant correlation filters application is the method to achieve invariance of image recognition in presence
of input object distortions. Composite filter with linear phase coefficients (LPCC filter) is one of the perspective
types of correlation filters. LPCCF can be realized in a scheme of optoelectronic Vander Lught's correlator as
synthesized holographic filters for recognition in real time conditions. Application of binary spatial light modulators
for realization of holographic LPCCF is especially interesting. Variants of "pixel to pixel" binarization
methods or representation of grayscale gradation using binary "subpixel" raster can be used for binary representation
of the initial hologram. The results of correlation recognition with binary amplitude holographic LPCCF
application are represented in the paper.
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