Modified method of image histogram hyperbolization

One of the methods to improve image quality, which consists in increasing the resolution of image details by contrast enhancement, is to hyperbolize the image histogram. Herewith this increase in local contrast is carried out indirectly. It is due to the nature of the change in the histogram of the transformed image. Usually the histogram of the input image is transformed so that it has a uniform distribution, which illustrates the same contribution of pixels gray level to the image structure. However, there is a method that is based on modeling the human visual system, which is characterized by the logarithmic dependence of the human reaction to light stimulation. It consists in the hyperbolic transformation of the histogram of the image. Then, due to its perception by the visual system, at its output, during the psychophysical perception of the image, an approximately uniform distribution of the histogram of the levels of gray pixels is formed. But the drawback is the lack of effectiveness of this approach for excessively light or dark images. The modified method of image histogram hyperbolization has been developed. It is based on the power transformation of the probability distribution function, which in the discrete version of the images is approximated by a normalized cumulative histogram. The power index is a control parameter of the transformation. to improve the darkened images we use the value of the control parameter less than one, and for light images more than one. The effectiveness of the proposed method is shown by examples.

Otoendoscopes to Enhance Telemedicine During the COVID-19 Pandemic

Objectives: As telemedicine has become increasingly utilized during the COVID-19 pandemic, portable otoendoscopy offers a method to perform an ear examination at home. The objective of this pilot study was to assess the quality of otoendoscopic images obtained by non-medical individuals and to determine the effect of a simple training protocol on image quality. Methods: Non-medical participants were recruited and asked to capture images of the tympanic membrane before and after completion of a training module, as well as complete a survey about their experience using the otoendoscope. Images were de-identified, randomized, and evaluated by 6 otolaryngologists who were blinded as to whether training had been performed prior to the image capture. Images were rated using a 5-point Likert scale. Results: Completion of a training module resulted in a significantly higher percentage of tympanic membrane visible on otoendoscopic images, as well as increased physician confidence in identifying middle ear effusion/infection, cholesteatoma, and deferring an in-person otoscopy ( P < .0001). However, even with improved image quality, in most cases, physicians reported that they would not feel comfortable using the images to for diagnosis or to defer an in-person examination. Most participants reported that the otoendoscope was simple to use and that they would feel comfortable paying for the device. Conclusions: At-home otoendoscopes can offer a sufficient view of the tympanic membrane in select cases. The use of a simple training tool can significantly improve image quality, though often not enough to replace an in-person otoscopic exam.

Usefulness of the Ultrasound in Hand Surgery: Part I

In the last years, ultrasonography (US) of the wrist and hand have increased in popularity. Technical advances led us to improve image quality and have the ability to see superficial soft-tissue structures with high resolution with the patient in our office.The advantages of US are the fact that it is noninvasive, its lack of ionising radiation, low cost, and portability. The dynamic real-time assessment in the office is an additional benefit.Ultrasound can be used in hand surgery for both diagnostic and therapeutic purposes. We can use US for injections with needle guidance, for the evaluation of soft-tissue masses, foreign bodies, tendon injuries, compressive neuropathies, and rheumatologic joint disease. It also helps us perform ultrasound-guided procedures: carpal tunnel syndrome, trigger finger, and intersection syndrome or compartimental syndrome.The aim of the present review is to describe different uses of US in hand surgery to show its important role of providing to the surgeon more information on the diseases of their patients.

3 T: the good, the bad and the ugly

It is around 20 years since the first commercial 3 T MRI systems became available. The theoretical promise of twice the signal-to-noise ratio of a 1.5 T system together with a greater sensitivity to magnetic susceptibility-related contrast mechanisms, such as the blood oxygen level dependent (BOLD) effect that is the basis for functional MRI (fMRI), drove the initial market in neuroradiology. However, the limitations of the increased field strength soon became apparent, including the increased radiofrequency (RF) power deposition, tissue dependent changes in relaxation times, increased artifacts, and greater safety concerns. Many of these issues are dependent upon MR physics and work arounds have had to be developed to try and mitigate their effects. This article reviews the underlying principles of the good, the bad and the ugly aspects of 3 T, discusses some of the methods used to improve image quality and explains the remaining challenges and concerns.

Contrast and Synthetic Multiexposure Fusion for Image Enhancement

Many hardware and software advancements have been made to improve image quality in smartphones, but unsuitable lighting conditions are still a significant impediment to image quality. To counter this problem, we present an image enhancement pipeline comprising synthetic multi-image exposure fusion and contrast enhancement robust to different lighting conditions. In this paper, we propose a novel technique of generating synthetic multi-exposure images by applying gamma correction to an input image using different values according to its luminosity for generating multiple intermediate images, which are then transformed into a final synthetic image by applying contrast enhancement. We observed that our proposed contrast enhancement technique focuses on specific regions of an image resulting in varying exposure, colors, and details for generating synthetic images. Visual and statistical analysis shows that our method performs better in various lighting scenarios and achieves better statistical naturalness and discrete entropy scores than state-of-the-art methods.

Comparison of 5 Rectal Preparation Strategies for Prostate MRI and Impact on Image Quality

Purpose: To compare 5 different rectal preparation strategies for prostate MRI. Methods: This 5-arm quality-assurance study evaluated 56 patients per arm (280 patients) including: no preparation, clear-fluids diet (CFD) beginning at 00:00 hours on the day of MRI, Fleet®-enema, enema + CFD, enema + CFD + IV-antispasmodic agent. The study was powered to 0.80 with alpha-error of 0.05. Three blinded radiologists independently evaluated T2-Weighted (T2W) and Diffusion Weighed Imaging (DWI) for: rectal diameter (maximal AP diameter), rectal content (stool, fluid, gas), rectal motion, T2W/DWI image quality, T2W image sharpness and DWI susceptibility artifact using 5-point Likert scales. Overall comparisons were performed using analysis of variance (ANOVA) and Kruskal-Wallis, with pair-wise comparisons using paired t-tests and Wilcoxon sign-rank tests. Results: Rectal diameter and amount of gas were lower in enema compared to non-enema groups (p < 0.001), with smallest diameter and least gas in the enema + CFD + IV-antispasmodic group (p = 0.022-<0.001). T2W image quality and sharpness were highest in the enema + CFD groups (p < 0.001) with no difference comparing enema + CFD with/without IV-antispasmodic (p = 0.064, 0.084). Motion artifact was least in enema + CFD + IV-antispasmodic group compared to all other groups (p < 0.001), followed by the enema + CFD group (p = 0.008-<0.001). DWI image quality was highest (p < 0.001) and DWI susceptibility artifact lowest (p < 0.001) in the enema + CFD groups (p < 0.001) and did not differ comparing enema + CFD with/without anti-spasmodic (p = 0.058-0.202). Conclusions: Use of enema + clear-fluids diet before prostate MRI yields the highest T2W and DWI image quality with the least DWI artifact. IV-antispasmodic use reduces motion on T2W but does not improve image quality on T2W or DWI, or lessen DWI artifact compared to enema + clear-fluids diet.

Computer-Generated Hologram Based on Reference Light Multiplexing for Holographic Display

In this article, we propose a reference light wave multiplexing scheme to increase the information capacity of computer-generated holograms. The holograms were generated by different reference light waves and superimposed together as a multiplexed hologram. A modified Gerchberg–Saxton algorithm was used to improve image quality, and different images could be reconstructed when the multiplexed hologram was illuminated by corresponding reference light waves. We performed both numerical simulations and optical experiments to demonstrate the feasibility of the proposed scheme. Numerical simulations showed that the proposed method could reconstruct multiple images successfully by a single multiplexed hologram and optical experiments are consistently good with numerical simulations. It is expected that the proposed method has great potential to be widely applied in holographic displays in the future.