Evaluating the Visual Quality of Watermarked Images

A recent image quality measure, M-SVD, can express the quality of distorted images either numerically or graphically. Based on the Singular Value Decomposition (SVD), it consistently measures the distortion across different distortion types and within a given distortion type at different distortion levels. The SVD decomposes every real matrix into

An SVD-based gray-scale image quality measure for local and global assessment

The important criteria used in subjective evaluation of distorted images include the amount of distortion, the type of distortion, and the distribution of error. An ideal image quality measure should therefore be able to mimic the human observer. We present a new gray-scale image quality measure that can be used as a graphical or a scalar measure to predict the distortion introduced by a wide range of noise sources. Based on the Singular Value Decomposition, it reliably measures the distortion not only within a distortion type at different distortion levels but also across different distortion types. The measure was applied to five test images (Airplane, Boat, Goldhill, Lena, and Peppers) using six types of distortion (JPEG, JPEG 2000, Gaussian blur, Gaussian noise, sharpening, and DC-shifting), each with five distortion levels. Its performance is compared with PSNR and two recent measures

A multidimensional image quality measure using singular value decomposition

The important criteria used in subjective evaluation of distorted images include the amount of distortion, the type of distortion, and the distribution of error. An ideal image quality measure should therefore be able to mimic the human observer. We present a new image quality measure that can be used as a multidimensional or a scalar measure to predict the distortion introduced by a wide range of noise sources. Based on the Singular Value Decomposition, it reliably measures the distortion not only within a distortion type at different distortion levels but also across different distortion types. The measure was applied to Lena using six types of distortion (JPEG, JPEG 2000, Gaussian blur, Gaussian noise, sharpening and DC-shifting), each with five distortion levels

Acute migraine therapy with external trigeminal neurostimulation (ACME): A randomized controlled trial

Objective: To assess the safety and efficacy of external trigeminal nerve stimulation for acute pain relief during migraine attacks with or without aura via a sham-controlled trial. Methods: This was a double-blind, randomized, sham-controlled study conducted across three headache centers in the United States. Adult patients who were experiencing an acute migraine attack with or without aura were recruited on site and randomly assigned 1:1 to receive either verum or sham external trigeminal nerve stimulation treatment (CEFALY Technology) for 1 hour. Pain intensity was scored using a visual analogue scale (0 = no pain to 10 = maximum pain). The primary outcome measure was the mean change in pain intensity at 1 hour compared to baseline. Results: A total of 109 participants were screened between February 1, 2016 and March 31, 2017. Of these, 106 patients were randomized and included in the intention-to-treat analysis (verum: n = 52; sham: n = 54). The primary outcome measure was significantly more reduced in the verum group than in the sham group: −3.46 ± 2.32 versus −1.78 ± 1.89 (p < 0.0001), or −59% versus −30% (p < 0.0001). With regards to migraine subgroups, there was a significant difference in pain reduction between verum and sham for ‘migraine without aura’ attacks: mean visual analogue scale reduction at 1 hour was −3.3 ± 2.4 for the verum group versus −1.7 ± 1.9 for the sham group (p = 0.0006). For ‘migraine with aura’ attacks, pain reduction was numerically greater for verum versus sham, but did not reach significance: mean visual analogue scale reduction at 1 hour was −4.3 ± 1.8 for the verum group versus −2.6 ± 1.9 for the sham group (p = 0.060). No serious adverse events were reported and five minor adverse events occurred in the verum group. Conclusion: One-hour treatment with external trigeminal nerve stimulation resulted in significant headache pain relief compared to sham stimulation and was well tolerated, suggesting it may be a safe and effective acute treatment for migraine attacks. Study protocol: ClinicalTrials.gov Identifier: NCT02590939. © International Headache Society 2018

Full-reference image guality metrics performance evaluation over image quality databases

A quantitative predictive performance evaluation of 18 well-known and commonly used full-reference image quality assessment metrics has been conducted in the present work. The process has been run over six publicly available and subjectively rated image quality databases for four degradation types namely JPEG and JPEG2000 compression, noise and Gaussian blur. Results show that the existing predictive performance evaluation tools of the different full-reference image quality metrics are significantly impacted by the choice of the image quality database. Three of them, namely Toyama, LIVE and TID, have been found to give different assessment results. The visual information fidelity (VIF) quality metric has been found to have superior predictive capabilities to its counterparts. MS-SSIM (multi-scale structural similarity index), MSSIM (modified SSIM) and VIFP (pixel-based VIF) have also closer performances in terms of their correlation to the subjective human ratings, accuracy and monotonicity to the VIF model