No abstract

No abstract

No abstract

Color constancy is an essential component of the human visual system. It enables us to discern the color of objects invariant to the illumination that is present. This ability is difficult to reproduce in software, as the underlying problem is ill posed, i.e., for each pixel in the image, we know only the RGB values, which are a product of the spectral characteristics of the illumination and the reflectance of objects, as well as the sensitivity of the sensor. To combat this, additional assumptions about the scene have to be made. These assumptions can be either handcrafted or learned using some deep learning technique. Nonetheless, they mostly work only for single illuminant images. In this work, we propose a method for learning these assumptions for multi-illuminant scenes using an autoencoder trained to reconstruct the original image by splitting it into its illumination and reflectance components. We then show that the estimation can be used as is or can be used alongside a clustering method to create a segmentation map of illuminations. We show that our method performs the best out of all tested methods in multi-illuminant scenes while being completely invariant to the number of illuminants.

A reliable determination of the basic physical properties and variability patterns of hot emission-line stars is important for understanding the Be phenomenon and ultimately, the evolutionary stage of Be stars. This study is devoted to one of the most remarkable Be stars, V1294 Aql = HD 184279. We collected and analysed spectroscopic and photometric observations covering a time interval of about 25000 d (68 yr). We present evidence that the object is a single-line 192.9 d spectroscopic binary and estimate that the secondary probably is a hot compact object with a mass of about 1.1-1.2 M . We found and documented very complicated orbital and long-term spectral, light, and colour variations, which must arise from a combination of several distinct variability patterns. Attempts at modelling them are planned for a follow-up study. We place the time behaviour of V1294 Aql into context with variations known for some other systematically studied Be stars and discuss the current ideas about the nature of the Be phenomenon.