Invariant correlation filter with linear phase coefficient holographic realization in 4-F correlator

Abstract

Realization of distortion invariant correlation filters in opticalimage 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. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Adaptive Digital Hologram Binarization Method Based on Local Thresholding, Block Division and Error Diffusion

“…It is widely used in processing textual images [51], unevenly illuminated documents [52], degraded archival [53] and historical [54] documents, etc. Threshold binarization has also become widely used in holography [2,22,[29][30][31][32][33]. Algorithms are based on separation of background components from the object ones.…”

“…Binary computer-generated and digital holograms are used for various DMD applications: holographic displays [2,[14][15][16], scattering media characterization [17], beam modulation [18], phase imaging [19], additive technologies [20], data coding [11], packaging [21], etc. Binary holograms are also widely used in other areas: image recognition and watermaking [22,23], creation of specially shaped beams [24], visualization of scanning holographic information [25], data compression [26] and storage [27], optical encryption [28], etc.…”

“…Many techniques have been investigated and developed for hologram binarization. The most common are local and global thresholding methods [2,22,[29][30][31][32][33] and error diffusion techniques [15,[34][35][36][37][38][39][40][41][42][43]. They are used both for binarization of optically registered digital holograms [15,30,32,33,37] and for computer-generated holograms [29,34,[38][39][40]43].…”

MINACE filter: variants of realization in 4-f correlator

“…8 The filter synthesized previously(ν = 1.24) have been used as reference (complex) object for holographic filter synthesis. As the most high-speed spatial light modulators have limited amount of transparency grayscale levels gradation, analysis of hologram grayscale levels suppression was performed.…”

Comparative analysis of off-axis digital hologram binarization by error diffusion

“…Binarization is one of the popular technologies in digital and computersynthesized holography . It is used, for example, to create holographic displays [51][52][53] and dynamic processes at optical frequencies [54], in problems of correlation image recognition and watermarking [55][56][57], for information compression and storage [58][59][60], fast 3D printing [61], etc. Binary * Author to whom any correspondence should be addressed.…”