Tick Hui Oh

JPEG2000 and JPEG: image quality measures of compressed medical images

Due to the constraints on bandwidth and storage capacity, medical images must be compressed before transmission and storage. However, when the image is compressed, especially at lower bit rates, the image fidelity is reduced, a situation which cannot be tolerated in the medical field. The paper studies the compression performance of the new JPEG2000 and the more conventional JPEG standards. The parameters compared include the compression efficiency, peak signal-to-noise ratio (PSNR), picture quality scale (PQS), and mean opinion score (MOS). Three types of medical images are used - X-ray, magnetic resonance imaging (MRI) and ultrasound. Overall, the study shows that JPEG2000 compression is more acceptable than, and superior to, JPEG in lossy compression.

MEDICAL IMAGE COMPRESSION USING JPEG-2000 AND JPEG: A COMPARISON STUDY

Due to the constrained bandwidth and storage capacity, medical images must be compressed before transmission and storage. However, compression will reduce image fidelity, especially when the image is compressed of lower bit rate, which cannot be tolerated in medical field. In this paper, the compression performance of the new JPEG-2000 and the more conventional JPEG is studied. The parameters used for comparison include the compression efficiency, peak signal-to-noise ratio (PSNR), picture quality scale (PQS), and mean opinion score (MOS). Three types of medical images are used — X-ray, magnetic resonance imaging (MRI) and ultrasound. Overall, the study shows that JPEG-2000 compression is more acceptable and superior compare to JPEG for lossy compression.

Medical Image Processing: From Lossless to Lossy Compression

Compressed image will always reduce the image fidelity. This is especially so if the image is compressed at lower bit rates, which most of the time cannot be tolerated. Compression is necessary in medical field due to the limited transmission bandwidth and storage capacity. In this paper, performance of the controversial lossy compression on medical modalities using the new JPEG2000 and the more conventional JPEG is being studied. The common objective measure, peak signal-to-noise ratio (PSNR) is definitely not adequate as a perceptual quality measurement. Therefore, subjective measures such as picture quality scale (PQS) and mean opinion score (MOS) are used as the benchmark instead, along with the statistical and frequency measures for the image characteristics evaluation. Three types of medical modalities are used - X-ray, ultrasound and computed tomography (CT). From these various measurements, the general acceptable compression bit rate for each of the medical modality is determined.

IMAGE TRANSMISSION THROUGH MC-CDMA CHANNEL: AN IMAGE QUALITY EVALUATION

The multicarrier code division multiple access (MC-CDMA) system is considered as an advancement in mobile communication system. Seen as the next generation communication technology after the 3G, signals can be easily transmitted and received using the Fast Fourier Transform (FFT) device without increasing the transmitter and receiver complexities. Besides, the MC-CDMA system provides good spectral efficiency. If the number of sub-carriers and the spacing between sub-carriers are chosen properly, it is unlikely that all the sub-carriers will be in deep fade. Thus, it provides frequency diversity. Frequency diversity means that frequencies separated by more than the coherence bandwidth of the channel will be uncorrelated and thus will not experience the same fades. Three types of MC-CDMA systems were proposed — MC-CDMA, multicarrier DS-CDMA and multitone CDMA. In MC-CDMA systems, the transmitter spreads the user data over different sub-carriers using spreading code (Hadamard Walsh code) in frequency domain. The multicarrier DS-CDMA system spreads the S/P converted data streams using spreading code in time domain. This scheme is proposed for uplink communication because this scheme can provide quasi-synchronization. In the MT-CDMA scheme, the S/P converted data stream is spread in time domain so that the spectrum of each sub-carrier prior to spreading operation can satisfy the orthogonality condition with minimum frequency separation. Thus, the spectrum of each sub-carrier no longer satisfies the orthogonality condition. MC-CDMA uses longer spreading code as compared to other schemes and thus accommodates more users. The JPEG2000 still image compression is a new image compression technique which is optimized not only for efficiency, but also for scalability and interoperability in network and mobile environment. This standard can provide superior low bit rate performance and continuous-tone and bi-level compression. Because of the robustness to bit errors, JPEG2000 is widely used in wireless communication channel.

JPEG2000 AND JPEG: A STATISTICAL APPROACH FOR LOSSILY COMPRESSED MEDICAL IMAGES QUALITY EVALUATION

Image compression will always reduce the image fidelity, especially when the image is compressed at lower bit rates, which cannot be tolerated, especially in medical field. But compression is necessary due to the constraint of transmission bandwidth and the limited storage capacity. In this paper, the bad compression performance of the new JPEG2000 and the more conventional JPEG are studied. Besides, using the common objective measures such as Peak Signal-to-Noise Ratio (PSNR) and Root Mean Square Error (RMSE) as the standard quality measurements, we focus more on the statistical and frequency measures as the image characteristics evaluation. Four types of medical modalities are used: X-ray, Magnetic Resonance Imaging (MRI), Ultrasound and Computed Tomography (CT). From these various measurements, we found the general acceptance compression bit rate for each of the medical modalities.

On the possibility of fuzzy application in learning outcome evaluation

This paper describes on the possibility of using fuzzy logic to evaluate learning outcomes (LOs) in outcome-based education system. We present both traditional LO as well as the fuzzy LO evaluation methods. We discuss both methods using student assessment marks and conclude on the possibility of employing fuzzy LO evaluation. We also compare the LO variation in evaluations of fuzzy method to traditional method using mean square error and find that to be small. Fuzzy method offers instructors the flexibility to modify the input assessment and output LO relationships, easier to set target outcome based on combination of these relationships and the process is akin to the humans reasoning.

Performance analysis of JPEG2000 transmission through low SNR MC-CDMA channel

The demand for high data rate transmission is ever increasing everyday. Multi-carrier code division multiple access (MC-CDMA) system is considered as the forerunner and advancement in the mobile communication system. In this paper, two types of JPEG2000 lossily-compressed test images are transmitted through an MC-CDMA channel in low SNR (as low as 4dB) environment and their quality are evaluated objectively by using peak signal-to-noise ratio (PSNR) and root mean square error (RMSE). The test images are all compressed in the ratios of 10∶1 up to 70∶1 and the system involves multi-user image transmission in near real-time low SNR (±5dB). It is found that JPEG2000 image compression technique that applies wavelet transform performed rather well in the low SNR multipath fading channel and it looks quite promising for future applications.

TELEMEDICINE IN MALAYSIA AND INDONESIA: THE IMPORTANCE, OPPORTUNITIES AND CHALLENGES

Telemedicine is an emerging industry with the potential to revolutionize the delivery of healthcare for the benefit of consumers, providers and payors. In general, telemedicine refers to the use of information and telecommunication technologies to distribute both information and expertise necessary for healthcare service provision, collaboration or delivery among geographically separated participants — physicians and patients. In short, it is a generic term which is used to define various aspects of healthcare at a distance. Telemedicine has been heralded as one of several possible solutions to some of the medical dilemmas that are faced by many developing countries. In this paper, we will discuss the current state of telemedicine in developing countries in South-East Asia (SEA) in general, with Malaysia and Indonesia in particular.

On the possibility of fuzzy method and its mathematical framework in OBE measurements

This paper describes the approach of using fuzzy logic to design a measurement system in outcome-based education (OBE). The traditional OBE and its measurement method are first presented. A fuzzy system is then designed based on the traditional OBE measurement. We have tested both systems using a set of course assessment and found the mean square errors between traditional OBE and fuzzy method to be small. We have further shown how the fuzzy system can be modified to accommodate different levels of difficulty based on course assessments and concluded on the possibility of employing fuzzy method in OBE measurements as it offers flexibility in tuning the input-output relationships of OBE course assessment.