B.T.P. Madhav

Histogram equalisation technique to analyse induced cholesteric phase in nanodoped liquid crystalline compound

The 1% Fe3O4 nanodoped in dodecyloxy benzoic acid induces cholesteric phase quenching the nematic phase that the pure compound exhibits. Further, the solid–solid transition also occurs when compared to the pure compound and the transition temperatures are reduced along with the cholesteric thermal ranges of LC phases. The histogram is the operation by which the occurrences of intensity value in the image is shown. Further, histogram equalisation is the technique through which the dynamic range of the histogram of an image can be increased. Histogram equalisation method is used in this article to analyse the 12Oba + 1% Fe3O4 nanodoped liquid crystalline textures by considering global and local image information and for the adjustment of image intensities to enhance the contrast. The basic idea of histogram equalisation is to remap the grey levels of the image, and this method is used to identify the uniform regions and detect the defects that are not clearly observed from the textures that are recorded by polarising microscope.

Image enhancement using virtual contrast image fusion on Fe3O4 and ZnO nanodispersed decyloxy benzoic acid

Low contrast and noisy photographic pictures can be considerably improved by image-processing techniques. Techniques like histogram equalisation produce high-contrast images but often fail to preserve the colour texture information. To overcome this deficiency, a contrast-enhancement approach has been devised, using virtual contrast image fusion (in Haar wavelet domain). This technique has been evaluated by a study of the optical textures of nano-dispersed decyloxybenzoic acid with small quantities of Fe3O4 and ZnO added.

Homomorphic filtering textural analysis technique to reduce multiplicative noise in the 11Oba nano-doped liquid crystalline compounds

The compound undecyloxy benzoic acid (11Oba) exhibits nematic and smectic-C phases while a nano-doped undecyloxy benzoic acid with ZnO exhibits the same nematic and smectic-C phases with reduced clearing temperature as expected. The doping is done with 0.5% and 1% ZnO molecules. The clearing temperatures are reduced by approximately 4 ° and 6 °, respectively (differential scanning calorimeter data). While collecting the images from a polarizing microscope connected with hot stage and camera, the illumination and reflectance combined multiplicatively and the image quality was reduced to identify the exact phase in the compound. A novel technique of homomorphic filtering is used in this manuscript through which multiplicative noise components of the image are separated linearly in the frequency domain. This technique provides a frequency domain procedure to improve the appearance of an image by gray level range compression and contrast enhancement.

Gradient measurement technique to identify phase transitions in nano-dispersed liquid crystalline compounds

Characterization and phase transitions in pure and 0.5% BaTiO3 nano-dispersed liquid crystalline (LC) N-(p-n-heptyloxybenzylidene)-p-n-nonyloxy aniline, 7O.O9, com-pounds are carried out using a polarizing microscope attached with hot stage and camera. We observed that when any of these images are distorted, different local structures suffer from various degradations in a gradient magnitude. So, we examined the pixel-wise gradient magnitude similarity between the reference and distorted images combined with a novel pooling strategy – the standard deviation of the GMS map – to determine the overall phase transition variations. In this regard, MATLAB software is used for gradient measurement technique to identify the phase transitions and transition temperature of the pure and nano-dispersed LC compounds. The image analysis of this method proposed is in good agreement with the standard methods like polarizing microscope (POM) and differential scanning calorimeter (DSC). 0.5% BaTiO3 nano-dispersed 7O.O9 compound induces cholesteric phase quenching the nematic phase, which the pure compound exhibits.

Multispectral correlations technique for finding phase transition temperatures in 7O.Om series

Transition temperatures in N-(p-n-heptyloxybenzylidene)-p-n-alkyloxy anilines, 7O.Om liquid crystalline compounds are computed from optical textures using Multispectral Correlations Technique in image processing. The statistical parameters like mean, standard deviation and entropy of textures as a function of temperature are computed from the image processing technique. These results show abrupt changes as a function of temperature, indicating the phase transition of the 7O.Om samples. The MATLAB simulation results are in good agreement with DSC results and the proposed methodology is one of the techniques in giving reliable and suitable technique to identify transition temperatures at low cost.

Identification of liquid crystalline phases in 7O.O9 compound based on structural similarity index measure

Textural analysis is done in the case of the thermotropic liquid crystal (LC), 4-heptyloxybenzylidene-4′-nonyloxyaniline, 7O.O9, using a polarising microscope attached with a hot stage with a high-resolution camera. Natural images are highly structured: their pixels exhibit strong dependencies and carry important information about the structure of the objects. In this article, we consider the structural similarity index measure parameter computed as a function of the temperature. The results exhibit abrupt changes with temperature showing different liquid crystalline phases. This statistical image analysis is compared with the differential scanning calorimeter data and good agreement was found. The proposed methodology is very sensitive and reliable technique to identify the LC phases.

Thermal and phase behaviour studies of hydrogen-bonded compounds (SA:nOBA) using POM, DSC and image-processing techniques

A novel series of hydrogen-bonded liquid crystals are synthesised. The hydrogen bond is formed between non-mesogenic salicylic acid and the mesogenic p-n-alkoxy benzoic acids with n = 4–8, 10–12 and 16. The formation of hydrogen bond is confirmed from infrared studies. The transition temperatures and the phase identification are made with the use of polarising microscope (POM) attached with a hot stage. Further, the heats of transition and enthalpies are obtained by employing the differential scanning calorimeter (DSC). Along with POM and DSC, textural image analysis is done by image-processing techniques using MATLAB software and transition temperatures are identified. The results reveal that the compounds with the chain number n = 7, 8, 10–12 show the manifestation of smectic-B phase by quenching smectic-C phase.

Image enhancement of nano-dispersed N-(p-n-decyloxybenzylidene)-p-n-hexyloxy aniline using combined unsharp masking

ABSTRACT The main objective of the image enhancement is to process an image with suitable technique to produce better visibility for a specific application. To identify key features like transition temperatures, clear phase identification in the liquid crystalline images, we require some novel image processing techniques. Characterisation and mesomorphic behaviour in pure and 1% ZnO nano-dispersed liquid crystalline N-(p-n-decyloxybenzylidene)-p-n-hexyloxy anilines, 10O.O6 compounds are carried out using a polarising microscope and images are preserved for enhancement. Both the compounds exhibits NACIG (nematic, smectic-A, smectic-C, smectic-I, smectic-G) phases and the transition temperatures of the 1% ZnO nano-dispersed 10O.O6 are reduced compared with pure 10O.O6. Further, in this paper, a novel image enhancement technique of combined unsharp masking is proposed on pure and 1% ZnO nano-dispersed 10O.O6 liquid crystalline compounds for better visibility of phases at transition temperatures. The proposed method is used to identify the uniform regions and to detect the defects which may not be clearly observed from the textures that are recorded by polarising microscope.

Pre-informed Level Set for Flower Image Segmentation

This work proposes a pre-informed Chan–Vese (CV) based level sets algorithm. Pre-information includes objects colour, texture and shape fused features. The aim is to use this algorithm to segment flower images and extract meaningful features that will help is classification of floral content. Shape pre-information modelling is handled manually using advance image processing tools. Local binary patterns (LBP) features makeup texture pre-information and RGB colour channels of the object provide colour pre-information. All pre-defined object information is fused together to for high dimension subspace defining object characteristics. Testing of the algorithm on flower images datasets shows a jump in information content in the resulting segmentation output compared to other models in the category. Segmentation of flowers is important for recognition, classification and quality assessment to ever-increasing volumes in floral markets.

Synthesis, characterization and phase transition studies in 4-hexyloxy benzylidene 4’-alkoxyanilines

ABSTRACT Synthesis and the characterization through polarizing optical microscope (POM) textures in number of 4-hexyloxy benzylidene 4’-alkoxyanilines, 6O.Om with m = 4, 6 to 10 liquid crystalline materials are carried out. Furthermore, the density and thermal expansion coefficient results reveal that the phase transitions present, viz., isotropic–nematic, nematic–SmC and SmC–SmI show first-order nature as expected. The transition temperatures obtained thorough the differential scanning calorimetry is found to be in agreement with the literature data. The first two compounds exhibit only the nematic phase while the next four compounds show enantiotropic SmC phase as per the literature data. The compound with m = 10 exhibits monotropic SmI phase. However, we, the authors, are able to observe this phase in addition to SmC and nematic through POM only as per the literature. The parameters calculated across the phase transitions and in the phases are in agreement with the body of the data available.