Two context-based filtering methods are introduced. The methods are based on statistical context modeling by gathering context-wise statistics from the entire image. Uncommon pixels in low information contexts are unconditionally inverted (simple context filter), or inverted conditionally depending whether the gain in compression overweighs the loss of information (gain-loss filter). Both metho...

AIM To analyze the optical quality after implantation of toric intraocular lens with optical quality analysis system. METHODS Fifty-two eyes of forty-four patients with regular corneal astigmatism of at least 1.00 D underwent implantation of AcrySof toric intraocular lens, including T3 group 19 eyes, T4 group 18 eyes, T5 group 10 eyes, T6 group 5 eyes. Main outcomes evaluated at 3mo of follow...

A number of schemes have been proposed to support QoS in optical burst-switched (OBS) networks. Most schemes only support relative QoS differentiation instead of absolute QoS guarantee. However, absolute QoS differentiation is a basic requirement for many delay and loss sensitive applications. In this paper, we propose two mechanisms for providing absolute QoS differentiation in OBS networks, a...

Packet-oriented PONs will offer an efficient way to transfer IP traffic, providing at the same time flexible Quality of Service mechanisms to support a great variety of services. To allow provisioning of connections from customer sites to ISP sub-networks across packet-based PONs, it is necessary to correlate the Ethernet MAC address used in the customer terminals to the ISP interfaces and the ...

The optical access fiber network is spreading rapidly as a result of the progress made on optical communication technologies and the availability of a wide range of broadband Internet content. If the optical access network is not properly maintained, the service quality will decrease. This paper describes some effective technologies that have been researched and developed to maintain a high qua...

BACKGROUND We assessed the effects of aging on visual function and optical quality in a healthy adult population and provide reference values for different age ranges. METHODS We conducted a prospective study with 198 healthy volunteers from 31 to 70 years of age. The visual acuity (VA) and contrast sensitivity (CS) at 3, 6, 12 and 18 cycles per degree (cpd) frequencies were assessed, togethe...

In the present paper, the recent applications of optical parametric amplifiers (OPAs) in hybrid wavelength division multiplexing (WDM)/time division multiplexing (TDM) local area passive optical networks have been modeled and parametrically investigated over wide range of the affecting parameters. Moreover, we have analyzed the ability of the hybrid WDM/TDM Passive optical networks to handle a ...

This paper reviews recent studies of the role of the tear film in the optical quality of the eye. Recent investigations focus on the dynamics of the tear film after a blink and its important role in the optical quality of the eye. The results in this review were used in an attempt to understand the optical and visual impact of tear-film breakup in normal eyes and dry eyes. It was noted that pat...

The expansion of wavefront-sensing techniques redefined the meaning of refractive error in clinical ophthalmology. Clinical aberrometers provide detailed measurements of the eye's wavefront aberration. The distribution and contribution of each higher-order aberration to the overall wavefront aberration in the individual eye can now be accurately determined and predicted. Using corneal or ocular...

A new and complete methodology of monofocal intraocular lens (IOL) design is presented aiming at isoplanatism, i.e. IOLs that provide the eye with optimized optical quality over a wide field of view (typically in a range of ten degrees). The methodology uses a merit function considering dimensional and biomechanical constraints, and a geometrical optical quality metric that is evaluated simulta...