Muhammad Imran Iqbal

Vascular intersection detection in retina fundus images using a new hybrid approach

The use of vascular intersection aberration as one of the signs when monitoring and diagnosing diabetic retinopathy from retina fundus images (FIs) has been widely reported in the literature. In this paper, a new hybrid approach called the combined cross-point number (CCN) method able to detect the vascular bifurcation and intersection points in FIs is proposed. The CCN method makes use of two vascular intersection detection techniques, namely the modified cross-point number (MCN) method and the simple cross-point number (SCN) method. Our proposed approach was tested on images obtained from two different and publicly available fundus image databases. The results show a very high precision, accuracy, sensitivity and low false rate in detecting both bifurcation and crossover points compared with both the MCN and the SCN methods.

Detection of vascular intersection in retina fundus image using modified cross point number and neural network technique

Vascular intersection can be used as one of the symptoms for monitoring and diagnosis of diabetic retinopathy from fundus images. In this work we apply the knowledge of digital image processing, fuzzy logic and neural network technique to detect bifurcation and vein-artery cross-over points in fundus images. The acquired images undergo preprocessing stage for illumination equalization and noise removal. Segmentation stage clusters the image into two distinct classes by the use of fuzzy c-means technique, neural network technique and modified cross-point number (MCN) methods were employed for the detection of bifurcation and cross-over points. MCN uses a 5x5 window with 16 neighboring pixels for efficient detection of bifurcation and cross over points in fundus images. Result obtained from applying this hybrid method on both real and simulated vascular points shows that this method perform better than the existing simple cross-point number (SCN) method, thus an improvement to the vascular point detection and a good tool in the monitoring and diagnosis of diabetic retinopathy.

A decision support framework for metrics selection in goal-based measurement programs: GQM-DSFMS

Software organizations face challenges in managing and sustaining their measurement programs over time. The complexity of measurement programs increase with exploding number of goals and metrics to collect. At the same time, organizations usually have limited budget and resources for metrics collection. It has been recognized for quite a while that there is the need for prioritizing goals, which then ought to drive the selection of metrics. On the other hand, the dynamic nature of the organizations requires measurement programs to adapt to the changes in the stakeholders, their goals, information needs and priorities. Therefore, it is crucial for organizations to use structured approaches that provide transparency, traceability and guidance in choosing an optimum set of metrics that would address the highest priority information needs considering limited resources. This paper proposes a decision support framework for metrics selection (DSFMS) which is built upon the widely used Goal Question Metric (GQM) approach. The core of the framework includes an iterative goal-based metrics selection process incorporating decision making mechanisms in metrics selection, a pre-defined Attributes/Metrics Repository, and a Traceability Model among GQM elements. We also discuss alternative prioritization and optimization techniques for organizations to tailor the framework according to their needs. The evaluation of the GQM-DSFMS framework was done through a case study in a CMMI Level 3 software company.

Perceptual-based quality assessment of error protection schemes for wireless JPEG2000

Designing wireless imaging services with acceptable quality imposes great challenges due to the severe impairments induced by wireless channels, high data rate demands and limited transmission bandwidth. In this paper, we examine different error protection schemes for the JPEG2000 codestream using the error control codes offered by the wireless JPEG2000 (JPWL) standard. In particular, two unequal error protection (UEP) schemes are considered. In the first scheme, only the initial and more important packets of the JPWL codestream are protected while the remaining packets are left without protection. In contrast, the second scheme uses a strong code for the initial packets while a weaker code is used for the tail packets. As quality of visual services may not be captured adequately with traditional link layer metrics, code selection and their performance assessment is based on perceptual quality metrics. Specifically, the LP-norm, structural similarity (SSIM) index and visual information fidelity (VIF) criterion are utilized. Numerical results are provided for a range of system conditions under which UEP outperforms conventional equal error protection in terms of perceptual quality metrics.

Error sensitivity analysis for wireless JPEG2000 using perceptual quality metrics

Quality assessment of mobile and wireless multimedia services including image and video applications has gained increased attention in recent years as a means of facilitating efficient radio resource management. In particular, approaches that utilize perceptual-based metrics are becoming more dominant, as conventional fidelity metrics such as the peak signal-to-noise ratio (PSNR) may not correlate well with quality as perceived by the human observer. In this paper, we focus on the error sensitivity analysis for images given in the wireless JPEG2000 (JPWL) format using perceptual quality metrics. Specifically, the perceptual quality improvements obtained by progressively decoding an increasing number of image packets are examined. It is shown that the considered perceptual quality metrics exploiting structural image features may accompany or replace the PSNR-based error sensitivity description (ESD) marker segment in the wireless JPEG2000 standard. This addition will increase the effectiveness of the ESD marker segment as it facilitates the communication of reduced-reference information about the image quality from the transmitter to the receiver. In addition, the proposed approach can be used to guide the design of preferential error control coding schemes, link adaptation techniques, and selective retransmission of packets with respect to their contribution to overall quality as perceived by humans.

A framework for error protection of region of interest coded images and videos

In this paper, we propose a framework for unequal error protection (UEP) of image and video streaming over a wireless channel. Our framework of allocating the parity symbols associated with error control coding to the image or video codestream takes advantage of the different levels of importance that particular spatial regions of visual multimedia content has to human observers. As such, it provides stronger protection against transmission impairments to those parts of an image or video stream that correspond to the regions of interest (ROIs) while weaker protection is applied to the background (BG). For this purpose, an image or video stream represented by a sequence of packets is split into smaller cells in such a way that certain cells contain the parts of a codestream that represent ROIs and the last cell carries solely BG information. The available parity budget obtained from the given code rate is then distributed among these cells based on their contribution to the overall perceptual quality of a reconstructed image or video. A dynamic programming approach is utilized to facilitate optimal allocation of parity to ROIs and BG for ROI based UEP. The performance of the proposed ROI based UEP scheme is analyzed and compared with both the optimal UEP without ROI processing and equal error protection (EEP) in terms of an objective perceptual quality metric, the structural similarity (SSIM) index. Performance results validate the effectiveness of our framework and the superior performance of the proposed UEP scheme compared to EEP. The performance of the proposed UEP scheme matches well with that of the optimal UEP without ROI processing, especially, for multiple spatial description image and video coding while computational complexity can be kept much lower.

Quality of Experience of Digital Multimedia Broadcasting Services : An Experimental Study

Digital multimedia broadcasting (DMB), also know as mobile TV, has been developed as a digital radio transmission technology that supports multimedia services such as TV, radio and datacasting. Especially, the terrestrial version of DMB, referred to as T-DMB, has been widely deployed in South Korea to deliver multimedia services to mobile devices ranging from smartphones to laptops, car navigation systems, and telematic devices for automotives. Although T-DMB is claimed to theoretically work without difficulties in vehicles with speeds up to 300 km/h, in practice, occasional skips and other temporal and spatial artifacts have been observed. In this paper, we provide an experimental study of the Quality of Experience (QoE) of T-DMB with focus on TV services. The study is based on a measurement campaign that was conducted in a live T-DMB system in South Korea consisting of TV broadcasters and DMB receivers in vehicles. In particular, a comprehensive subjective test has been conducted on the DMB test material that was obtained in the measurement campaign. A statistical analysis of the user ratings obtained from the subjective tests is reported to quantify the QoE of T-DMB in terms of mean opinion scores (MOSs) and higher order statistics. The obtained results may be used to develop related QoE models for this type of systems and services. In particular, the results may suggest to exploit insights obtained from higher order statistics such as skewness and kurtosis into QoE modeling rather than considering only MOS and variance.

Analysis and modeling of optimal error protection for embedded codestreams

Efficient utilization of bandwidth is key to providing mobile multimedia services such as wireless imaging. As such, efficient allocation of the available parity budget for error protection of the associated codestreams is essential for ensuring quality of service. Computing the optimal parity allocation to the codestream packets may not be possible in real-time due to the huge number of ways the parity can be assigned to the codestream packets. This is particularly true for systems having limited resources, such as mobile handheld devices. As a result, it is important to provide an error-protection scheme that gives good error-protection performance while imposing low computational and memory demands on the system. We therefore analyze how different parameters such as signal-to-noise ratio and source distortion-rate function affect the optimal unequal error protection (UEP) scheme for embedded codestreams. We also propose to approximate the optimal UEP using suitable mathematical models in order to reduce the complexity that otherwise would occur with computing the optimal UEP. We investigate several models for their fitness in approximating the optimal UEP using different performance metrics. The simulation results show that most of these models provide an excellent trade-off between performance and complexity.

Real-time unequal error protection for wireless imaging

In this paper, we propose a new unequal error protection (UEP) scheme for wireless imaging. Our technique is based on approximating the optimal parity distribution using offline and online processing. For a given parity budget and signal-to-noise ratio (SNR), the offline processing is responsible for obtaining the optimal parity distribution and an approximation of it using polynomial curve fitting. Subsequently, in the online processing, the obtained polynomial parameters are used to regenerate the parity distribution curve. Eventually, channel codes are assigned to the packets of the codestream based on the regenerated parity distribution curve. The complexity of the proposed technique is very low which makes it suitable for realtime wireless imaging, especially for mobile devices that have low processing power and operate with very low memory. Despite having very low complexity, the proposed UEP technique gives still close to optimal performance.