Fast Color Removal Method Considering Differences between Colors

When a color image is converted into a monochrome one, luminance components of the pixels have been used as gray-levels for the representation of the monochrome image in HDTV standard. However, saliencies of the image embedded only in the chrominance components are disappeared in the monochrome image converted by using luminance components. To cope with this problem, A.A. Gooch et al. have proposed the salience-preserving color removal method called “Color2Gray.” The monochrome image well reected the impression of an input color image can be yielded by Color2Gray. However, the calculation cost of that algorithm is tremendous, and its utility is not so much. In this paper, fast Color2Gray algorithms are proposed. The effectiveness of the proposed method is illustrated through the experiments

Multiscale Retinex with Data-dependent Offset

As one of methods to improve the image quality, there is a method called multiscale retinex (MSR) which has been proposed by D.J. Jobson et al. In MSR, the reection components of an image are extracted and emphasized, and then the image with improved quality is obtained. This method is very useful and powerful especially for the visibility improvement of dark regions of the image. However, the resulting image tends to give us the unnatural impression because luminance components are removed, and the global contrast of the image is decreased in the processing. In this paper, a new MSR with a variable offset, which changes dependently on the local luminance information of the image, is proposed in order to overcome the disadvantage of the conventional MSR, and to further improve the image quality. Through the experiments, the effectiveness of the proposed method is illustrated

Time Variability of Nonthermal X-ray Stripes in Tycho's Supernova Remnant with Chandra

Analyzing Chandra data of Tycho's supernova remnant (SNR) taken in 2000, 2003, 2007, 2009, and 2015, we search for time variable features of synchrotron X-rays in the southwestern part of the SNR, where stripe structures of hard X-ray emission were previous found. By comparing X-ray images obtained at each epoch, we discover a knot-like structure in the northernmost part of the stripe region became brighter particularly in 2015. We also find a bright filamentary structure gradually became fainter and narrower as it moved outward. Our spectral analysis reveal that not only the nonthermal X-ray flux but also the photon indices of the knot-like structure change from year to year. During the period from 2000 to 2015, the small knot shows brightening of $\sim 70\%$ and hardening of $\Delta \Gamma \sim 0.45$. The time variability can be explained if the magnetic field is amplified to $\sim 100~\mathrm{\mu G}$ and/or if magnetic turbulence significantly changes with time.Comment: 8 pages, 3 figures, 2 tables, accepted for publication in Ap

Recombining Plasma and Hard X-ray Filament in the Mixed-Morphology Supernova Remnant W44

We report new features of the typical mixed-morphology (MM) supernova remnant (SNR) W44. In the X-ray spectra obtained with Suzaku, radiative recombination continua (RRCs) of highly ionized atoms are detected for the first time. The spectra are well reproduced by a thermal plasma in a recombining phase. The best-fit parameters suggest that the electron temperature of the shock-heated matters cooled down rapidly from $\sim1$,keV to $\sim 0.5$,keV, possibly due to adiabatic expansion (rarefaction) occurred $\sim20,000$ years ago. We also discover hard X-ray emission which shows an arc-like structure spatially-correlated with a radio continuum filament. The surface brightness distribution shows a clear anti-correlation with $^{12}$CO (J=2-1) emission from a molecular cloud observed with NANTEN2. While the hard X-ray is most likely due to a synchrotron enhancement in the vicinity of the cloud, no current model can quantitatively predict the observed flux.Comment: 10 pages, 5 figures, accepted for publication in PAS

The repeating dislodgement of an ASO device

Transcatheter closure with an Amplatzer Septal Occluder (ASO) has become the standard treatment for secundum atrial septal defect (ASD). However, this procedure is associated with complications, such as device dislodgement. A 52-year-old woman was admitted with exertional dyspnea. Transesophageal echocardiography showed an ASD involving a 29 mm defect. Calculated Qp/Qs was 5.6 and all the rims were > 5 mm, with the exception of the posterior rim, which was 3 mm. Transcatheter ASD closure with an ASO was performed under general anesthesia. During emergence from anesthesia, tachycardia developed and the ASO device became dislodged. Hemodynamic changes associated with the end of anesthetic administration were believed to have led to device dislodgement. In a second transcatheter ASD closure, a low dose of propofol and remifentanil was maintained during emergence from anesthesia to reduce hemodynamic changes. However, device dislodgement occurred with nonsustained ventricular tachycardia. Finally, surgical ASD closure was performed. The large defect size, high Qp/Qs, and rim deficiency may have predisposed to device dislodgement after transcatheter ASD closure with ASO. The risk of device dislodgement should be considered in advance of surgery and, in high-risk cases, the patient's cardiovascular status should be closely monitored