KEYWORDS: Image segmentation, Tumors, Brain, Magnetic resonance imaging, Neuroimaging, Data modeling, Computer programming, 3D modeling, Network architectures, Systems modeling
Brain tumors have existed for a long time, but their rate is increasing among all age groups. Early detection is essential for timely prognosis as it is a dangerous and life-threatening disease. Since the advent of artificial intelligence and machine learning, different algorithms have been proposed to classify and segment brain tumors. However, all have their limitations when it comes to local deployment. The main drawback is designing multiple architectures for multiple tasks, which increases the time and computational complexity and affects performance. This paper addresses this drawback by proposing a multi-task learning (MTL) model that can take 2D-magnetic resonance imaging (MRI) images as input and gives predictions for multiple outputs such as detection and segmentation. It gives two outputs from one architecture: the system’s efficiency. Brain Tumor Segmentation (BRaTs) 2019 and BRaTs 2020 dataset has been used to evaluate the proposed architecture. Experimental results show that the best model shows 98% accuracy for detecting MRI images as either normal/abnormal, whereas an overall Dice score of 92% for multi-class segmentation of high-grade glioma gliomas into the whole tumor, enhancing tumor and core tumor. The overall performance of the proposed architecture proves that it can be the best-suited framework for clinical setup.
We present a holistic technique for recognition of text in cursive scripts using printed Urdu ligatures as a case study. Convolutional neural networks (CNNs) are trained on high-frequency ligature clusters for feature extraction and classification. A query ligature presented to the system is first divided into primary and secondary ligatures that are separately recognized and later associated in a postprocessing step to recognize the complete ligature. Experiments are carried out using transfer learning on pretrained networks as well as by training a network from scratch. The technique is evaluated on ligatures extracted from two standard databases of printed Urdu text, Urdu printed text image (UPTI) and Center of Language Engineering (CLE), as well as by combining the ligatures of the two datasets. The system realizes high recognition rates of 97.81% and 89.20% on the UPTI and CLE databases, respectively.
Owing to a large number of spectral bands, it is always a challenge to devise an optimal visualization method for hyperspectral images. An algorithm must maintain a balance between dimensionality reduction and restoration of maximum spectral information. A methodology for visualization of hyperspectral imagery is proposed based on extraction of salient regions. For that, spectral bands are selected from different combinations of principal component analysis, minimum noise fraction, and saliency maps. A hierarchical fusion method is proposed, which is applied on the selected bands to obtain a final three band RGB image. The qualitative and quantitative results of the proposed method are very encouraging once compared with other state-of-the-art methods.
Deep learning is revolutionizing the already rapidly developing field of computer vision. The convolutional neural network (CNN) is a state-of-the-art deep learning tool that learns high level features directly from a huge dataset of labeled images. In document image processing, ink analysis allows for determination of ink age and forgery and identification of pen or writer. The spectral information of inks in hyperspectral document images provides valuable information about the underlying material and thus helps in identification and discrimination of inks based on their unique spectral signatures even if they have the same color. Ink mismatch detection is a key step in document forgery detection. Although various ink mismatch detection techniques are available in the recent literature, there is a constant need for development of more accurate and effective methods to empower automated document forgery detection. A state-of-the-art deep learning method for ink mismatch detection in hyperspectral document images is proposed. The spectral responses of ink pixels are extracted from a hyperspectral document image, reshaped to a CNN-friendly image format and fed to the CNN for classification. The proposed method effectively identifies different ink types in a hyperspectral document image for forgery detection and achieves an overall accuracy of 98.2% for blue and 88% for black inks, which is the highest accuracy among the latest techniques of ink mismatch detection on the UWA Writing Ink Hyperspectral Images (WIHSI) database and differentiates between the highest number of inks mixed in unbalanced proportions in a hyperspectral document image. Furthermore, a detailed discussion on selection of appropriate CNN architecture and classification results are presented in this paper along with comparison with the former methods of ink mismatch detection. This research opens a new window for research on automated forgery detection in hyperspectral document images using deep learning.
Leaf water content (LWC) is an essential constituent of plant leaves that determines vegetation health and its productivity. An accurate and on-time measurement of water content is crucial for planning irrigation, forecasting drought, and predicting woodland fire. The retrieval of LWC from visible to shortwave infrared (VSWIR: 0.4 to 2.5 μm) has been extensively investigated but little has been done in the mid- and thermal-infrared (MIR and TIR: 2.50 to 14.0 μm) windows of electromagnetic spectrum. This study is mainly focused on retrieval of LWC from MIR and TIR, using genetic algorithm (GA) integrated with partial least square regression (PLSR). GA fused with PLSR selects spectral wavebands with high predictive performance, i.e., yields high adjusted-R2 and low root-mean-square error (RMSE). In our case, GA-PLSR selected eight variables (bands) and yielded highly accurate models with adjusted-R2 of 0.93 and RMSE cross validation equal to 7.1%. This study also demonstrated that MIR is more sensitive to the variation in LWC as compared to TIR. However, the combined use of MIR and TIR spectra enhances the predictive performance in retrieval of LWC. The integration of GA and PLSR not only increases the estimation precision by selecting the most sensitive spectral bands but also helps in identifying the important spectral regions for quantifying water stresses in vegetation. The findings of this study will allow the future space missions (like HyspIRI) to position wavebands at sensitive regions for characterizing vegetation stresses.
Leaf Water Content (LWC) is an essential constituent of plant leaves that determines vegetation heath and its productivity. An accurate and on-time measurement of water content is crucial for planning irrigation, forecasting drought and predicting woodland fire. The retrieval of LWC from Visible to Shortwave Infrared (VSWIR: 0.4-2.5 μm) has been extensively investigated but little has been done in the Mid and Thermal Infrared (MIR and TIR: 2.50 -14.0 μm), windows of electromagnetic spectrum. This study is mainly focused on retrieval of LWC from Mid and Thermal Infrared, using Genetic Algorithm integrated with Partial Least Square Regression (PLSR). Genetic Algorithm fused with PLSR selects spectral wavebands with high predictive performance i.e., yields high adjusted-R2 and low RMSE. In our case, GA-PLSR selected eight variables (bands) and yielded highly accurate models with adjusted-R2 of 0.93 and RMSEcv equal to 7.1 %. The study also demonstrated that MIR is more sensitive to the variation in LWC as compared to TIR. However, the combined use of MIR and TIR spectra enhances the predictive performance in retrieval of LWC. The integration of Genetic Algorithm and PLSR, not only increases the estimation precision by selecting the most sensitive spectral bands but also helps in identifying the important spectral regions for quantifying water stresses in vegetation. The findings of this study will allow the future space missions (like HyspIRI) to position wavebands at sensitive regions for characterizing vegetation stresses.
This work presents an analytical study on the relevance of features in an existing framework for writer identification
from offline handwritten document images. The identification system comprises a set of 15 features combining the
orientation and curvature information in a writing with the well-known codebook based approach. This study aims to
find the optimal feature subset to identify the author of a questioned document while maintaining acceptable
identification rates. Employing a genetic algorithm with a wrapper method we carry out a feature selection mechanism
and identify the most relevant features that characterize the writer of a handwritten document.
In this paper, we present a new sliding window based local thresholding technique 'NICK' and give a detailed
comparison of some existing sliding-window based thresholding algorithms with our method. The proposed method aims
at achieving better binarization results, specifically, for ancient document images. NICK has been inspired from the
Niblack's binarization method and exhibits its robustness and effectiveness when evaluated on low quality ancient
document images.
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