Quality assessment is a central issue in the design, implementation, and performance testing of all systems. digital signal processing systems generally deal with visual information that are meant for human consumptio...
Quality assessment is a central issue in the design, implementation, and performance testing of all systems. digital signal processing systems generally deal with visual information that are meant for human consumption. An image, a video, or a 3d model may go through different stages of processing before being presented to a human observer, and each stage of processing may introduce distortions that could reduce the quality of the final display. To conceive quantitative metrics that can automatically predict the perceived quality, the way humans perceive such distortions has to be taken into account and can be greatly beneficial for quality assessment. In general, an objective quality metric plays an important role in a broad range of applications, such as visual information acquisition, compression, analysis and watermarking. Quality metrics can be used to optimize algorithm parameter settings and to benchmark different processing systems and algorithms. In this dissertation, new objective quality metrics that take into account how distortions are perceived, are proposed and three different signal processing systems are considered: video water- marking, video object segmentation and3d models watermarking. First, two new objective metrics for watermarked video quality assessment are proposed. Based on several different watermarking algorithms and video sequences, the most predominant distortions are identified as spatial noise and temporal flicker. Corresponding metrics are designed and their performance is tested through subjective experiments. Second, the problem of video object segmentation quality evaluation is discussed, proposing both subjective evaluation methodology and perceptual objective quality metric. Since a perceptual metric requires a good knowledge of the kinds of artifacts present in segmented video objects, the most typical artifacts are synthetically generated. Psychophysical experiments are carried out to study the perception of individual arti
The advances in radiographic imaging techniques that have occurred within the past decades have significantly enhanced our abilities to display anatomy as well as pathology. Although imageacquisition commonly generat...
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ISBN:
(纸本)0819427012
The advances in radiographic imaging techniques that have occurred within the past decades have significantly enhanced our abilities to display anatomy as well as pathology. Although imageacquisition commonly generates three-dimensional datasets, limitation in user interfaces generally requires that this information be presented clinically as a series of two dimensional images. Consequently, during preoperative planning, surgeons are required to mentally transform a wealth of two dimensional hard copy images qualitatively into three-dimensional concepts that are used as a road map to surgery. The sugeron's success is dependent on the accurate mental transfer of Computer Tomographic X-ray (CT) and Magnetic Resonance (MR) imaging information to the operative site to assist direct visual perception of the procedure. Thus, the surgical procedure is performed with the surgeon intuitively transferring radiographic information to the surgical site. Neurosurgeons, for example, are especially hampered because of limited ability to visually distinguish tumor tissue, peritumoral edema, and normal brain parenchyma. This limitation at least partially accounts for the relatively high incidence of subtotal tumor excision. Based on the need to assit the surgeon transform the preoperative scans to the operative site, stereotactic systems were developed and would evolve into frameless stereotaxy with the advance of various sensors.
The use of conventional videocameras at standard broadcast rates permits 30 frame per second videocapture and recording. Even when moving events are recorded with fast shuttering to preclude blurring(e.g. 1000th secon...
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ISBN:
(纸本)0819423661
The use of conventional videocameras at standard broadcast rates permits 30 frame per second videocapture and recording. Even when moving events are recorded with fast shuttering to preclude blurring(e.g. 1000th second) each recorded consecutive stopped action still has a 33 millisecond interval between them. The reason for this is the finite time necessary to serially dump recorded information from the microchip sensor, and reinitialize the sensor for the next capture event. By designing a parallel video chip with multiple, independently capable segments for sensor input/ output/ re-initialization, the duration of the interval required for unloading and resetting the entire sensor is decreased by the number of discrete segments in the chip, and the number of unloading ports to transfer data. Silicon Mountain design, Inc. (SMd) developed a 16 parallel channel output 512 x 512 x 8 bit digital videocamera, and a suitable memory buffer to absorb 256 full images. This camera has the uniquely advantageous feature that no imagedata is absorbed while the camera discharges its image to the parallel output ports. With this parallel videocamera it is possible to record events at 1000th second (or faster) continuously, or at least until the memory buffer fills. The use of structured light stereo numerical camera technology requires the collection of a series of video images, each video-image containing a different 'exposure' of an object with a different pattern of structured laser beams projected onto it. The complete series of images creates a temporal-spatial encoding of the laser beams necessary to calculate a 3-d numerical recreation of the object. By using a parallel videocamera, the collection of a complete series is limited by the time it takes to expose each video-image, plus the time it takes to change the light pattern being projected. Using a rapid ferric liquid crystal electro-optic modulator with a 1 millisecond cycle time, and an SMd parallel videocamera cyclin
Multiecho MR acquisition yields various information about tissue and csf characteristics. The analysis of two-dimensional scatterplots generated from dual-echo MR data turns out to be a useful tool. It allows the opti...
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