Significance of Color Spaces & their Selection for Image Processing: A Survey

: The human visual system is encompassed with three components that help to produce a color sensation. The color display devices use this concept and create their full range of colors by incorporating all three primary color components. Any displayable color can be created with the help of these primaries. This paper comprises the concept of color space, which helps to understand a particular device’s color proficiencies. Since colors are a more robust descriptor, color spaces are considered to play a significant role in representing an image appropriately. The performance of many algorithms depends on the selection of an appropriate color space. There are many kinds of color spaces that can be used in real-time applications. These are RGB, nRGB, HSV, TSL, YCbCr, YUV, YES, CIE-XYZ, CMYK, etc. In this paper, color spaces and their vast classification are described in brief. Apart from these, the characteristics, applicability, limitations, mathematical conversion, and other essential factors are also explained for each color space.

Synesthesia does not help to recover perceptual dominance following flash suppression

Grapheme-color synesthesia is a perceptual phenomenon that occurs when letters or numbers elicit an abnormal color sensation (e.g., printed black letters are perceived as colored graphemes). Grapheme-color synesthesia is typically reported following explicit presentation of graphemes. Very few studies have investigated color sensations in synesthesia in the absence of visual awareness. To address this issue, we took advantage of the dichoptic flash suppression paradigm to temporarily render a stimulus presented to one eye invisible. Synesthesic alphanumeric and non-synesthetic abstract stimuli were presented to 11 synesthete and 11 matched control participants in achromatic and chromatic experimental conditions. The test stimulus was first displayed to one eye and then masked following the sudden presentation of visual noise in the other eye. The time for an image to be perceived following the onset of the suppressive noise was calculated in each condition. Trials free of flash suppression but mimicking the perceptual suppression of the flash were also tested. Results showed that target detection by synesthetes was significantly better than by controls in the absence of flash suppression. However, no statistically significant difference was found between the groups when the test stimulus was interocularly suppressed, either for synesthetic or non-synesthetic stimuli. This study suggests that synesthesia can be associated with enhanced perception for overt recognition, but does not occur in the absence of visual awareness.

On the Ancestry of Reid’s Inquiry

Reid’s rejection of the “theory of ideas” implies that sensations are not copies of external qualities such as extension and figure. Reid also says that not even the order of sensations is spatial. However, in his early manuscripts Reid did not deny that sensations are arranged spatially. He simply denied that our ideas of extension and figure are copied from any single atomic sensation. Only subsequently did Reid explicitly reject the view that sensations are arranged spatially. The question of the spatiality of color sensation was a central concern of early interpreters of Reid, like Dugald Stewart, John Fearn, and William Hamilton. In particular, John Fearn thought that the denial of the spatiality of color sensations is the result of Reid’s commitment to the immateriality of the soul. Against Reid’s view, Fearn argued that the perception of visible figure necessarily implies the spatiality of color sensations.

Neurologic Adverse Events Associated with Voriconazole Therapy: Report of Two Pediatric Cases

Although voriconazole, a triazole antifungal, is a safe drug, treatment with this agent is associated with certain adverse events such as hepatic, neurologic, and visual disturbances. The current report presents two cases, one a 9-year-old boy and the other a 17-year-old girl, who experienced neurologic side effects associated with voriconazole therapy. Our aim is to remind readers of the side effects of voriconazole therapy in order to prevent unnecessary investigations especially for psychological and ophthalmologic problems. The first case was a 9-year-old boy with cystic fibrosis and invasive aspergillosis that developed photophobia, altered color sensation, and fearful visual hallucination. The second case was a 17-year-old girl with cystic fibrosis and allergic bronchopulmonary aspergillosis, and she experienced photophobia, fatigue, impaired concentration, and insomnia, when the dose of voriconazole therapy was increased from 12 mg/kg/day to 16 mg/kg/day. The complaints of the two patients disappeared after discontinuation of voriconazole therapy. Our experience in these patients reminded us of the importance of being aware of the neurologic adverse events associated with voriconazole therapy in establishing early diagnosis and initiating prompt treatment. In addition, although serum voriconazole concentration was not measured in the present cases, therapeutic drug monitoring for voriconazole seems to be critically important in preventing neurologic side effects in pediatric patients.

COLOR SENSATION - A PSYCHOLOGICAL ANALYSIS

Experimental studies in psychology began before experimental studies of sensation began. Tichner, Boring, Jastrow, Elesh Young, Helmholz, Herring, Ladd, Fankerlin, etc. carried out experimental studies of sensation. The experimental study of different sensations in various disciplines of science was started in the early nineteenth century. Wunt 1874 distinguished differences between sentencing and articulation. In the nineteenth century, more than fifty percent of work in the field of psychology was related to sensory psychology.Sensation is a normal, simple and first process of the brain. Light is a radiated energy, the waves produced from it are studied as a magnetic or electric current. Sunlight consists of waves of different colors. Newton 1966, with the help of prism, observed that sunlight has all the colors of rainbow and sunlight is made up of different colors. If the sensation arising from various stimuli touches the collector (the brainstem of the brain), a vibrations are produced in the body's nerve which is called electrochemical power. This nervous flow plays its role in sending sensory messages to the respective center in the brain through the sensory nerve. To a certain extent, stimulants are capable of producing sensations in humans. The electromagnetic waves produced by excitation, ranging in length from 400 micro millimeters to 800 micromillimeters, are capable of producing visual sensations. मनोविज्ञान में प्रयोगशालीय अन्वेषण से पहले ही संवेदना का प्रयोगात्मक अध्ययन प्रारम्भ हुआ । टिचनर, बोरिंग, जैस्ट्रो, एलेश यंग, हेल्महोल्ज, हेरिंग, लैड, फैंक्रलिन आदि ने संवेदना का प्रायोगात्मक अध्ययन किया । विभिन्न संवेदनाओं का प्रयोगात्मक अध्ययन विज्ञान के विभिन्न विषयों में उन्नीसवीं शताब्दी के प्रारम्भ में ही आरम्भ हो गया था। वुण्ट 1874 ने संवदेना और प्रत्यक्षीकरण में अंतर स्पष्ट किया। उन्नीसवीं शताब्दी में मनोविज्ञान के क्षेत्र में पचास प्रतिशत से अधिक कार्य संवेदना मनोविज्ञान से संबंधित था।संवेदना मस्तिष्क की सामान्य, सरल तथा प्रथम प्रक्रिया है। प्रकाश एक विकीर्ण ऊर्जा है, इससे उत्पन्न तरंगों का अध्ययन चुम्बकीय अथवा विद्युतीय धारा के रूप में किया जाता हैं। सूर्य के प्रकाश में विभिन्न रंगों की तरंगें सम्मिलित होती है। न्यूटन 1966 ने प्रिज्म की सहायता से देखा कि सूर्य के प्रकाश में इन्द्रधनुष के संभी रंग होते है एवं सूर्य का प्रकाश विभिन्न रंगों से मिलकर बना हैं। विभिन्न उद्दीपक से उत्पन्न संवेदना संग्राहको (ज्ञानवाही स्नायुतंत्र) को स्पर्श करती है तो शरीर के स्नायु में एक स्पन्दन उत्पन्न होता है जिसे विद्युत रासायनिक शक्ति कहा जाता है। यही स्नायु प्रवाह ज्ञानवाही स्नायु के द्वारा मस्तिष्क में सम्बन्धित केन्द्र तक संवेदना रूपी संदेश पहुँचाने में अपनी भूमिका निभाता है। एक निश्चित सीमा तक उत्तेजक मनुष्य में संवेदना उत्पन्न करने में सक्षम होते है। उत्तेजना से उत्पन्न विद्युत चुम्बक तरंगे जिनकी लंबाई 400 माइक्रो मिलीमीटर से 800 माइक्रोमिलीमीटर तक होती है, दृष्टि संवेदनाएँ उत्पन्न करने में सक्षम होती हैं।