Optical Fourier techniques for medical image processing and phase contrast imaging
TL;DR: Improvement of microcalcifications in a mammogram for early diagnosis of breast cancer is the main focus and the intensity dependent refractive index can be exploited as a phase filter for phase contrast imaging with a coherent source.
About: This article is published in Optics Communications.The article was published on 2008-04-01 and is currently open access. It has received 36 citations till now. The article focuses on the topics: Phase-contrast imaging & Image processing.
Citations
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TL;DR: Optical processing of images has received much attention recently as mentioned in this paper, mainly by studying correlation applications for identification and tracking, two-dimensional and three-dimensional holography, compression and encryption of images, etc.
Abstract: Optical processing of images has received much attention recently. Experimental breakthroughs have been achieved mainly by studying correlation applications for identification and tracking, two-dimensional and three-dimensional holography, compression and encryption of images, etc. While images are originally optical, numerical processing is often realized to fully exploit their information content. Within this context, our aim is to review the recent progress made in the field of optical processing of information. We consider techniques allowing us to increase image quality to render them more useful for correlation and reconstruction applications. The chapter is divided in two parts. In the first part, techniques for increasing image quality are described in detail. Interestingly, those dealing with color encoding are addressed. In addition, methods for denoising images are dealt with. The second part considers the polarization encoding methods. Throughout this review chapter, many examples illustrating the performances of these techniques are given. Future prospects for optimizing current techniques of optical processing of images are suggested.
61 citations
TL;DR: The technique introduces the concept of soft clusters within a neural network layer and combines them with least squares for optimising neural network weights to increase the generalisation ability of the neural network.
56 citations
Cites background from "Optical Fourier techniques for medi..."
...Optical Fourier transforms [15] and wavelet transforms are effective on micro calcification where the high spatial frequency in the Fourier spectrum allows for their identification, but may not be as accurate on masses where a lower spatial frequency exists similar to the surrounding tissues....
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TL;DR: The special opportunities and challenges that attend correlated imaging are explored by specific reference to correlated mass spectrometric and Raman imaging, a topic of substantial and growing interest.
Abstract: Correlated chemical imaging is an emerging strategy for acquisition of images by combining information from multiplexed measurement platforms to track, visualize, and interpret in situ changes in the structure, organization, and activities of interesting chemical systems, frequently spanning multiple decades in space and time. Acquiring and correlating information from complementary imaging experiments has the potential to expose complex chemical behavior in ways that are simply not available from single methods applied in isolation, thereby greatly amplifying the information gathering power of imaging experiments. However, in order to correlate image information across platforms, a number of issues must be addressed. First, signals are obtained from disparate experiments with fundamentally different figures of merit, including pixel size, spatial resolution, dynamic range, and acquisition rates. In addition, images are often acquired on different instruments in different locations, so the sample must be registered spatially so that the same area of the sample landscape is addressed. The signals acquired must be correlated in both spatial and temporal domains, and the resulting information has to be presented in a way that is readily understood. These requirements pose special challenges for image cross-correlation that go well beyond those posed in single technique imaging approaches. The special opportunities and challenges that attend correlated imaging are explored by specific reference to correlated mass spectrometric and Raman imaging, a topic of substantial and growing interest.
53 citations
TL;DR: It is shown that either isotropic or anisotropic edge enhancement in any desired orientation can be performed by operating the same spatial filter setup in different illuminating polarization states.
Abstract: Using polarization as an additional parameter apart from amplitude and phase in spatial filtering experiments offers additional advantages and possibilities. An S-waveplate that can convert a linearly polarized light into radially or azimuthally polarized light can also be used for isotropic edge enhancement. For anisotropic edge enhancement, introduction of a polarizer at the output was recommended and edge selection was done by orientation of the polarizer. But the full potential of the S-waveplate as a spatial filter has not been exploited so far. Unlike the standard amplitude and phase-based Fourier filters, which are independent to the state of polarization of the illuminating beam, the S-waveplate acts in a different way depending on the state of polarization. The edge selection does not need to be carried out by changing the orientation of the polarizer. With a fixed polarizer at the output, we show that either isotropic or anisotropic edge enhancement in any desired orientation can be performed by operating the same spatial filter setup in different illuminating polarization states.
41 citations
TL;DR: In this paper, the authors briefly review experimental techniques exploiting all-optical Fourier image processing inside the 4f system in order to characterize nonlinear refractive indices and compare them with well-known nonlinear characterization techniques such as degenerate four wave mixing, I-scan and Z-scan.
41 citations
References
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TL;DR: A multiple page fully digital holographic data storage system is demonstrated, used to store and retrieve digital image and compressed video data with a photorefractive crystal.
Abstract: A multiple page fully digital holographic data storage system is demonstrated. This system is used to store and retrieve digital image and compressed video data with a photorefractive crystal. Architecture issues related to spatio-rotational multiplexing and novel error-correcting encoding techniques used to achieve low bit-error rates are discussed.
574 citations
TL;DR: By use of the Fourier decomposition of a low-coherence optical image field into two spatial components that can be controllably shifted in phase with respect to each other, a new high-transverse-resolution quantitative-phase microscope has been developed.
Abstract: By use of the Fourier decomposition of a low-coherence optical image field into two spatial components that can be controllably shifted in phase with respect to each other, a new high-transverse-resolution quantitative-phase microscope has been developed. The technique transforms a typical optical microscope into a quantitative-phase microscope, with high accuracy and a path-length sensitivity of lambda/5500, which is stable over several hours. The results obtained on epithelial and red blood cells demonstrate the potential of this instrument for quantitative investigation of the structure and dynamics associated with biological systems without sample preparation.
466 citations
TL;DR: The proposed approach uses a two-stage algorithm for spot detection and shape extraction that opens up the possibility of a reproducible segmentation of microcalcifications, which is a necessary precondition for an efficient screening program.
Abstract: A systematic method for the detection and segmentation of microcalcifications in mammograms is presented. It is important to preserve size and shape of the individual calcifications as exactly as possible. A reliable diagnosis requires both rates of false positives as well as false negatives to be extremely low. The proposed approach uses a two-stage algorithm for spot detection and shape extraction. The first stage applies a weighted difference of Gaussians filter for the noise-invariant and size-specific detection of spots. A morphological filter reproduces the shape of the spots. The results of both filters are combined with a conditional thickening operation. The topology and the number of the spots are determined with the first filter, and the shape by means of the second. The algorithm is tested with a series of real mammograms, using identical parameter values for all images. The results are compared with the judgement of radiological experts, and they are very encouraging. The described approach opens up the possibility of a reproducible segmentation of microcalcifications, which is a necessary precondition for an efficient screening program. >
240 citations