Gray-tone Image Research Articles

Remodelling of the fibre-aggregate structure of collagen gels by cancer-associated fibroblasts: A time-resolved grey-tone image analysis based on stochastic modelling.

Solid tumors consist of tumor cells associated with stromal and immune cells, secreted factors and extracellular matrix (ECM), which together constitute the tumor microenvironment. Among stromal cells, activated fibroblasts, known as cancer-associated fibroblasts (CAFs) are of particular interest. CAFs secrete a plethora of ECM components including collagen and modulate the architecture of the ECM, thereby influencing cancer cell migration. The characterization of the collagen fibre network and its space and time-dependent microstructural modifications is key to investigating the interactions between cells and the ECM. Developing image analysis tools for that purpose is still a challenge because the structural complexity of the collagen network calls for specific statistical descriptors. Moreover, the low signal-to-noise ratio of imaging techniques available for time-resolved studies rules out standard methods based on image segmentation. In this work, we develop a novel approach based on the stochastic modelling of the gel structure and on grey-tone image analysis. The method is then used to study the remodelling of a collagen matrix by migrating breast cancer-derived CAFs in a three-dimensional spheroid model of cellular invasion imaged by time-lapse confocal microscopy. The structure of the collagen at the scale of a few microns consists in regions with high fibre density separated by depleted regions, which can be thought of as aggregates and pores. The approach developped captures this two-scale structure with a clipped Gaussian field model to describe the aggregates-and-pores large-scale structure, and a homogeneous Boolean model to describe the small-scale fibre network within the aggregates. The model parameters are identified by fitting the grey-tone histograms and correlation functions of the images. The method applies to unprocessed grey-tone images, and it can therefore be used with low magnification, noisy time-lapse reflectance images. When applied to the CAF spheroid time-resolved images, the method reveals different matrix densification mechanisms for the matrix in direct contact or far from the cells. We developed a novel and multidisciplinary image analysis approach to investigate the remodelling of fibrillar collagen in a 3D spheroid model of cellular invasion. The specificity of the method is that it applies to the unprocessed grey-tone images, and it can therefore be used with noisy time-lapse reflectance images of non-fluorescent collagen. When applied to the CAF spheroid time-resolved images, the method reveals different matrix densification mechanisms for the matrix in direct contact or far from the cells.

Tripartite sub-image histogram equalization for slightly low contrast gray-tone image enhancement

In this paper, a neoteric tripartite sub-image histogram equalization method is proposed to enhance slightly low contrast gray-tone images, which is a less explored area in the literature. An image is decomposed into three sub-images to preserve its mean brightness, and the histograms of the sub-images are calculated. Then, the snipping procedure is applied to each histogram to constrain the pace of contrast enhancement. Subsequently, the equalization of the three histograms is performed independently, and finally, the three equalized sub-images are composed into a single image. The proposed method offers better outcomes as compared to several common and state-of-the-art histogram equalization-based methods regarding contrast improvement, blind/reference-less image spatial quality evaluator, mean brightness preservation, peak signal-to-noise ratio, mean structural similarity, gradient magnitude similarity deviation, feature similarity, bit-plane to bit-plane similarity, and visual image quality.

Crowd Detection in Still Images Using Combined HOG and SIFT Feature

<p>Person detection and tracking in crowd is a challenging task. We detect the head region and based on this head region we can detect people from crowd. Individual object detection has been improved significantly in recent times but the crowd detection and tracking contains some challenges. Crowd analysis is a highly focused area for law enforcement, urban engineering and traffic management. There are a lot of incident occurred in crowd area during some fabulous event. In this research low resolution and verities of image orientation is a key factor as well as overlapping person images in crowd misguided the system. An enhanced system of interest point detection based on gradient orientation information as well as improved feature extraction HOG is used for identifying the human head or face from crowd. We have analyzed different types of images in different varieties and found accuracy 88-90%. In a number of applications, such as document analysis and some industrial machine vision tasks, binary images can be used as the input to algorithms that perform useful tasks. These algorithms can handle tasks ranging from very simple counting tasks to much more complex recognition, localization, and inspection tasks. Thus by studying binary image analysis before going on to gray-tone and color images, one can gain insight into the entire image analysis process.</p>

A New Quaternion-Based Encryption Method for DICOM Images.

In this paper, a new quaternion-based lossless encryption technique for digital image and communication on medicine (DICOM) images is proposed. We have scrutinized and slightly modified the concept of the DICOM network to point out the best location for the proposed encryption scheme, which significantly improves speed of DICOM images encryption in comparison with those originally embedded into DICOM advanced encryption standard and triple data encryption standard algorithms. The proposed algorithm decomposes a DICOM image into two 8-bit gray-tone images in order to perform encryption. The algorithm implements Feistel network like the scheme proposed by Sastry and Kumar. It uses special properties of quaternions to perform rotations of data sequences in 3D space for each of the cipher rounds. The images are written as Lipschitz quaternions, and modular arithmetic was implemented for operations with the quaternions. A computer-based analysis has been carried out, and the obtained results are shown at the end of this paper.

Towards Video Display on Electronic Papers

The electronic paper has been successfully applied on electronic readers (E-Readers). Among all electronic paper technologies, the electrophoretic display (EPD) would be the most popular one due to its promising visual quality for showing text only contents or gray-tone images. However, playing videos/animations on the EPD is still a big challenge, thus none of the commercial E-Readers can support such a fancy feature. This drawback limits the application scenarios of the E-Readers. In this paper, we propose an integrated driving system for playing videos on the EPD. The system contains a new real-time signal processing hardware engine for video halftoning. In addition, the entire system is driven with a new driving waveform aiming at the reduction of residue images and visual flickers.

Digital Fingerprinting Based on Quaternion Encryption Scheme for Gray-Tone Images

In this paper a new idea of digital images fingerprinting is proposed. The method is based on quaternion encryption in the Cipher Block Chaining (CBC) mode. Quaternions are hyper-complex numbers of rank 4 and thus often applied to mechanics in three-dimensional space. The encryption algorithm described in the paper is designed for graytone images but can easily be adopted for color ones. For the encryption purpose, the algorithm uses the rotation of data vectors presented as quaternions in a three-dimensional space around another quaternion (key). On the receiver’s side, a small amount of unnoticeable by human eye errors occurs in the decrypted images. These errors are used as a user’s digital fingerprint for the purpose of traitor tracing in case of copyright violation. A computer-based simulation was performed to scrutinize the potential presented quaternion encryption scheme for the implementation of digital fingerprinting. The obtained results are shown at the end of this paper.

Instructed perception in prenatal ultrasound examinations

The purpose of this study is to elucidate various practices for the structuring of images on an ultrasound monitor during prenatal ultrasound examinations. This study focuses on the practices that healthcare providers employ to invite pregnant women to differentiate a gray-tone image on the ultrasound monitor from the image’s background. In sequential environments in which pregnant women display difficulty in differentiating an image on the screen in response to the healthcare provider’s invitation, the healthcare provider employs practices that require additional bodily involvement to structure the images on the screen. Furthermore, on certain occasions, the healthcare provider also points to a particular abdominal location with the ultrasound transducer, which is held against the abdomen to produce the very image being differentiated. This study demonstrates that the image on the ultrasound monitor is intrinsically embodied and spatially (between the screen and the participants’ bodies) and modally (among vocal/auditory, visual, and tactile modes of orientation) distributed. In addition, the study suggests an interaction-organizational ground for an aspect of the ‘personification of the fetus’ through obstetric ultrasound.

A novel photographic approach for monitoring the structural heterogeneity and diversity of grassland ecosystems

Aims Studies that investigate the space-filling heterogeneity of biological structures in plant communities remain scarce. The main objective of this study was to evaluate the relationship between newly developed photographic measures of structural heterogeneity in digital images and plant species composition in the context of a long-term grassland experiment. Methods We tested a close-range photographic protocol using measures of structural heterogeneity in gray-tone images, namely mean infor mation gain (MIG) and spatial anisotropy, to assess differences in the compositional (species richness) and functional characteristics (plant height and flowering) of 78 managed grassland communities. We also implemented a random placement model of community assembly to explore the links between our measures of structural complexity and the geometric pattern of plant communities. Important Findings MIG and spatial anisotropy correlated with the growth and species richness of grassland communities. Simulations showed that structural heterogeneity in gray-tone digital images is a function of the size distribution and orientation pattern of plant modules. This easy, fast and non-destructive methodological approach could eventually serve to monitor the diversity and integrity of various ecosystems at different resolutions across space and time.

Gray tone image watermarking with complementary computer generated holography

We present herein an original approach for the watermarking of holograms in gray tone images for use in microscopic halftone image archiving. Our concept is based on the principle of complementary holography presented in a previous contribution. The efficiency of the concept is evaluated theoretically and experimentally. We demonstrate the interest of elliptical diffraction patterns as an alternative to the usual rectangular diffraction patterns and confirm the subsidiary role of the hologram amplitude in the hologram recovery process.

Adaptive Shape Diagrams for Multiscale Morphometrical Image Analysis

Shape diagrams are integral geometric representations in the Euclidean plane introduced to study 2D connected compact sets. Such a set is represented by a point within a shape diagram whose coordinates are morphometrical functionals defined as normalized ratios of geometrical functionals. In addition, the General Adaptive Neighborhoods (GANs) are spatial neighborhoods defined around each point of the spatial support of a gray-tone image, that fit with the image local structures. The aim of this paper is to introduce and study the GAN-based shape diagrams, which allow a gray-tone image morphometrical analysis to be realized in a local, adaptive and multiscale way. The GAN-based shape diagrams will be illustrated on standard images and also applied in the biomedical and materials areas.

Adaptive generalized metrics, distance maps and nearest neighbor transforms on gray tone images

This paper aims to introduce and study two novel metrics on gray tone images. These metrics are based on the General Adaptive Neighborhood Image Processing (GANIP) framework that enables to represent an image by spatial neighborhoods, named General Adaptive Neighborhoods (GAN) that fit to their local context. These metrics are generalized in the sense that they do not satisfy all the axioms of a standard mathematical metric. This notion of adaptive generalized metrics leads to the definition of relevant GAN distance maps and GAN nearest neighbor transforms used for image segmentation.

A geometric-based method for recognizing overlapping polygonal-shaped and semi-transparent particles in gray tone images

A geometric-based method is proposed to recognize the overlapping particles of different polygonal shapes such as rectangular, regular and/or irregular prismatic particles in a gray tone image. The first step consists in extracting the salient corners, identified by their locations and orientations, of the overlapping particles. Although there are certain difficulties like the perspective geometric projection, out of focus, transparency and superposition of the studied particles. Then, a new clustering technique is applied to detect the shape by grouping its correspondent salient corners according to the geometric properties of each shape. A simulation process is carried out for evaluating the performance of the proposed method. Then, it is particularly applied on a real application of batch cooling crystallization of the ammonium oxalate in pure water. The experimental results show that the method is efficient to recognize the overlapping particles of different shapes and sizes.

Automatic archaeological feature extraction from satellite VHR images

Archaeological applications need a methodological approach on a variable scale able to satisfy the intra-site (excavation) and the inter-site (survey, environmental research). The increased availability of high resolution and micro-scale data has substantially favoured archaeological applications and the consequent use of GIS platforms for reconstruction of archaeological landscapes based on remotely sensed data. Feature extraction of multispectral remotely sensing image is an important task before any further processing. High resolution remote sensing data, especially panchromatic, is an important input for the analysis of various types of image characteristics; it plays an important role in the visual systems for recognition and interpretation of given data. The methods proposed rely on an object-oriented approach based on a theory for the analysis of spatial structures called mathematical morphology. The term “morphology” stems from the fact that it aims at analysing object shapes and forms. It is mathematical in the sense that the analysis is based on the set theory, integral geometry, and lattice algebra. Mathematical morphology has proven to be a powerful image analysis technique; two-dimensional grey tone images are seen as three-dimensional sets by associating each image pixel with an elevation proportional to its intensity level. An object of known shape and size, called the structuring element, is then used to investigate the morphology of the input set. This is achieved by positioning the origin of the structuring element to every possible position of the space and testing, for each position, whether the structuring element either is included or has a nonempty intersection with the studied set. The shape and size of the structuring element must be selected according to the morphology of the searched image structures. Other two feature extraction techniques were used, eCognition and ENVI module SW, in order to compare the results. These techniques were applied to different archaeological sites in Turkmenistan (Nisa) and in Iraq (Babylon); a further change detection analysis was applied to the Babylon site using two HR images as a pre–post second gulf war. We had different results or outputs, taking into consideration the fact that the operative scale of sensed data determines the final result of the elaboration and the output of the information quality, because each of them was sensitive to specific shapes in each input image, we had mapped linear and nonlinear objects, updating archaeological cartography, automatic change detection analysis for the Babylon site. The discussion of these techniques has the objective to provide the archaeological team with new instruments for the orientation and the planning of a remote sensing application.

Simple multilevel halftoning excelled in gradation reproducibility

A simple multilevel halftoning method, which is based on the conventional error diffusion method and realizes halftoning excelled in the distribution of dots, is proposed. The proposed method consists of three steps, e.g., the image decomposition, the generation of binary halftone images by the error diffusion, and the synthesis of a multilevel halftone image, and each step does not require a complicated algorithm. The effectiveness of the proposed method is indicated by applying it to three- and four-level halftoning of gray-tone and natural images.

Angle multiplexed storage with object beam alone

Making use of the interference of incident light waves and the accompanying fanning waves in a photorefractive LiNbO3 crystal, the authors have recorded binary images as well as gray-tone images in a crystal with only an object beam. Angle multiplexing has also been demonstrated with this one beam recording method. Basing on a model that the recording is accomplished through the interference of the object light and its fanning light, the authors have estimated the minimal angular separation for achieving a cross-talk-free multiplexing.

Stacked Euler Vector (SERVE): A Gray-Tone Image Feature Based on Bit-Plane Augmentation

A new combinatorial feature called Stacked Euler Vector (SERVE) is introduced to characterize a gray-tone image. SERVE comprises a four-tuple, where each element is an integer representing the Euler number of the partial binary image formed by certain pixel overlap relations among the four most significant bit planes of the gray-tone image. Computation of SERVE is simple, fast, and does not involve any floating point operation. SERVE can be used to augment other features to improve the performance of image retrieval significantly. Experimental results on the COIL database are reported to demonstrate its performance.

Modelling and segmentation of colour images in polar representations

The suitability of polar representation for quantitative image processing tasks is investigated. The classical colour polar-based representations (HLS, HSV, etc.) lead to brightness and saturation with nonconsistent properties. After a short critical analysis of the gamma correction, a new polar representation using the L 1 norm is proposed. It satisfies several quantitative requirements. The relevance of this representation is demonstrated by means of luminance/saturation histograms, which exhibit typical alignments. Their physical interpretation leads to a model for light reception in terms of linearly regionalized spectra. A full example illustrates the application of the histogram approach. Colour images are multivariable functions, and for segmenting them one must go through a reducing step. It is classically obtained by calculating a gradient module, which is then segmented as a grey tone image. An alternative solution is proposed. It is based on separated segmentations, followed by a final merging into a unique partition. The generalisation of the top-hat transformation for extracting colour details is also considered. These new marginal colour operators take advantage of an adaptive combination of the chromatic and the achromatic (or the spectral and the spatio-geometric) colour components.

OVERSEGMENTATION REDUCTION BY FLOODING REGIONS AND DIGGING WATERSHED LINES

The watershed transformation is a primary tool for segmenting a grey-tone image into subsets that are of interest to a visual observer. The resulting image, however, may often appear oversegmented into a large number of tiny regions (basins), most of which are not significant to the problem of domain. In this paper, a method for removing these nonsignificant basins is presented. The notions of relative significance and intrinsic significance are introduced, which lead to the definition of three types of significance for a basin: strong, weak and partial. The merging of a basin with other basins only occurs when the significance of the basin is not strong, and is restricted to suitably selected adjacent basins. The merging is performed by using an iterated process consisting of two phases. The first involves the removal of certain regional minima, and is accomplished by following either a flooding or a digging scheme. The second identifies the basins corresponding to the regional minima remaining in the image and utilizes the watershed transformation. An appropriate selection of the basins to be merged produces a segmented image perceptually close to the original image. The performance of the proposed method is for the case of astronomic images.

68.1: Invited Paper: Achieving Graytone Images in a Microencapsulated Electrophoretic Display

Microencapsulated electrophoretic imaging films have been developed for a variety of display applications. These films exhibit an “ink-on-paper” appearance owing to their strong, near lambertian light scattering. Image persistence exhibited by these films allows displays to operate without power outside of image updates. This and their ready incorporation into flexible displays make microencapsulated imaging films attractive for portable devices where readability in a wide variety of lighting conditions, low power consumption, and mechanical robustness are important. This report reviews the basic principles of optical and electronic performance of E Ink's microencapsulated electrophoretic films as well as recent advances in driving methods for achieving high-quality graytone images in highresolution, active-matrix displays.

Euler Vector for Search and Retrieval of Gray-Tone Images

A new combinatorial characterization of a gray-tone image called Euler Vector is proposed. The Euler number of a binary image is a well-known topological feature, which remains invariant under translation, rotation, scaling, and rubber-sheet transformation of the image. The Euler vector comprises a 4-tuple, where each element is an integer representing the Euler number of the partial binary image formed by the gray-code representation of the four most significant bit planes of the gray-tone image. Computation of Euler vector requires only integer and Boolean operations. The Euler vector is experimentally observed to be robust against noise and compression. For efficient image indexing, storage and retrieval from an image database using this vector, a bucket searching technique based on a simple modification of Kd-tree, is employed successfully. The Euler vector can also be used to perform an efficient four-dimensional range query. The set of retrieved images are finally ranked on the basis of Mahalanobis distance measure. Experiments are performed on the COIL database and results are reported. The retrieval success can be improved significantly by augmentiong the Euler vector by a few additional simple shape features. Since Euler vector can be computed very fast, the proposed technique is likely to find many applications to content-based image retrieval.