Quality asessment of coded images using numerical category scaling

1995 ◽  
Author(s):  
Andre M. van Dijk ◽  
Jean-Bernard Martens ◽  
Andrew B. Watson
Keyword(s):  
Category Scaling ◽  
Coded Images

Monitoring water, sanitation, and hygiene (WASH) programmes in Timor-Leste with time-stamped, geo-coded images

Waterlines ◽  
2012 ◽  
Vol 31 (4) ◽  
pp. 293-305 ◽  
Author(s):  
Emily Christensen Rand ◽  
Crispen Wilson ◽  
Jessica Mercer
Keyword(s):  
Sanitation And Hygiene ◽  
Timor Leste ◽  
Coded Images

scholarly journals JPEG Quality Transcoding Using Neural Networks Trained with a Perceptual Error Measure

1999 ◽  
Vol 11 (1) ◽  
pp. 267-296 ◽  
Author(s):  
John Lazzaro ◽  
John Wawrzynek
Keyword(s):  
Prototype System ◽  
Training Procedure ◽  
Human Visual Perception ◽  
Error Measure ◽  
Jpeg Image ◽  
Perceptual Error ◽  
Image File ◽  
Visual Artifacts ◽  
Error Metric ◽  
Coded Images

A JPEG Quality Transcoder (JQT) converts a JPEG image file that was encoded with low image quality to a larger JPEG image file with reduced visual artifacts, without access to the original uncompressed image. In this article, we describe technology for JQT design that takes a pattern recognition approach to the problem, using a database of images to train statistical models of the artifacts introduced through JPEG compression. In the training procedure for these models, we use a model of human visual perception as an error measure. Our current prototype system removes 32.2% of the artifacts introduced by moderate compression, as measured on an independent test database of linearly coded images using a perceptual error metric. This improvement results in an average PSNR reduction of 0.634 dB.

Does tinnitus originate from hyperactive nerve fibers in the cochlea?

1984 ◽  
Vol 98 (S9) ◽  
pp. 38-44 ◽  
Author(s):  
Richard S. Tyler
Keyword(s):  
Basilar Membrane ◽  
Tuning Curve ◽  
Nerve Fibers ◽  
Frequency Resolution ◽  
Signal Frequency ◽  
Physiological Data ◽  
Pitch Matching ◽  
Category Scaling ◽  
Tinnitus Masking ◽  
Peripheral Origin

AbstractThis paper discusses the possibility of a localized peripheral origin of tinnitus. A working hypothesis is that tinnitus represents either aperiodic or periodic hyperactivity in the spontaneous activity of nerve fibers originating from a restricted place on the basilar membrane. The limited physiological data available support both hyperactive and hypoactive nerve fiber. Psychophysical data are not easy to interpret. Subjective descriptions and category scaling are too dependent on individual experience. Pitch matching can be reliable, but cannot distinguish between peripheral or central tinnitus. In one experiment we compared the masking of tinnitus to the masking of a pure tone, where the signal frequency and level were obtained from the tinnitus pitch and loudness matching. The results indicate that the broad tinnitus masking patterns are not typically due to the poor frequency resolution observed in sensorineural hearing loss. However, in a few subjects there was some correspondence between the shape of the tuning curve and the tinnitus masking pattern. In another study, we masked tinnitus with narrowband noises of different bandwidths. In some patients, there was a ‘critical bandwidth’ effect; wider masker bandwidths required greater overall sound pressures to mask the tinnitus. We conclude that the results from these studies taken together indicate that there are different types of tinnitus, some of which may have a localized peripheral origin.

Detection methods for blocking artefacts in transform coded images

2014 ◽  
Vol 8 (8) ◽  
pp. 435-444
Author(s):  
Jagroop Singh ◽  
Dilbag Singh ◽  
Moin Uddin
Keyword(s):  
Detection Methods ◽  
Coded Images
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