إختبار

Silent films

Early silent films had stated frame rates anywhere from 16 to 24 frames per second (FPS), but since the cameras were hand-cranked, the rate often changed during the scene to fit the mood. Projectionists could also change the frame rate in the theater by adjusting a rheostat controlling the voltage powering the film-carrying mechanism in the projector.Silent films were often intended to be shown at higher frame rates than those used during filming

These frame rates were enough for the sense of motion, but it was perceived as jerky motion. To minimize the perceived flicker, projectors employed dual- and triple-blade shutters, so each frame was displayed two or three times, increasing the flicker rate to 48 or 72 Hertz and reducing eye strain. Thomas Edison said that 46 frames per second was the minimum needed by the visual cortex: “Anything less will strain the eye.”

In the mid to late 1920s, the frame rate for silent films increased to between 20 and 26 FPS.

Frame rate

The temporal sensitivity and resolution of human vision varies depending on the type and characteristics of visual stimulus, and it differs between individuals. The human visual system can process 10 to 12 images per second and perceive them individually, while higher rates are perceived as motion.

Modulated light (such as a computer display) is perceived as stable by the majority of participants in studies when the rate is higher than 50 Hz through 90 Hz. This perception of modulated light as steady is known as the flicker fusion threshold. However, when the modulated light is non-uniform and contains an image, the flicker fusion threshold can be much higher, in the hundreds of hertz.

With regard to image recognition, people have been found to recognize a specific image in an unbroken series of different images, each of which lasts as little as 13 milliseconds

Persistence of vision sometimes accounts for very short single-millisecond visual stimulus having a perceived duration of between 100 ms and 400 ms. Multiple stimuli that are very short are sometimes perceived as a single stimulus, such as a 10 ms green flash of light immediately followed by a 10 ms red flash of light perceived as a single yellow flash of light

Mohab Kamel

Born in Egypt and spending the remainder of his early adolescence in Bahrain, Mohab Kamel returned to Egypt to complete high school and begin his degree in Mass Communications (Journalism) at October 6 University.

Mohab developed a passion for photojournalism at an early age, when his father gave him his first camera, a Nikon FA 1987 model – which he still has today.

He worked for Al Wafd Newspaper as a photojournalist and enjoyed a brief stint as a photojournalist for Associated Press. His talents were officially recognised by Al Jazeera in 2011 for his photo coverage of the Egyptian Revolution.

Since then, Mohab worked at some TV channels as a producer and decided to focus on freelance photography.

In early 2013, he moved to Australia to start and pursue a new life and new dream, and he is based in Sydney and working as a freelance photographer and a radio broadcaster at SBS.

إختبار لموضوع عربي

ضاقت بهم مصر فقرروا البحث عن الرزق فى أرض الله الواسعة، 12 ألفاً و985 مصرياً عدد من هاجروا من مصر فى الفترة من عام 1993 حتى الربع الأول من العام الحالى، وسجل عاما 96، و97 أكبر عدد للمصريين المهاجرين خلال الـ23 سنة الماضية، بمعدل 2128 مهاجراً، أما فى عامى 2011 و2012 فبلغ عددهم على التوالى نحو 446، و534 مصرياً، وسجل الربع الأول من العام الحالى هجرة 100 مصرى.

وزيرة القوى العاملة والهجرة الدكتورة ناهد عشرى أكدت أن بلدان المهجر خلال تلك الفترة استقبلت 5022 فى أمريكا، و4099 فى كندا، و2137 فى إيطاليا، و1068 فى أستراليا، و243 فى نيوزيلندا، و416 فى بلدان أخرى، وأضافت أن عدد الذكور من المهاجرين بلغ 10 آلاف، و268 مهاجراً، فى حين بلغ عدد الإناث ألفين و713 مهاجرة، إضافة إلى 4 مهاجرين غير مبين نوعهم. وكشفت بيانات قطاع شئون الهجرة بوزارة الداخلية أن عدد الحاصلين على بكالوريوس التجارة من المهاجرين بلغ 1935، والهندسة 1540، والطب 730، والعلوم 526، والصيدلة 498، والزراعة 464، والعلوم الإدارية وليسانس الحقوق 208، والآداب 517، ودبلوم التجارة 922، والصنايع 997، والثانوية العامة 833، والإعدادية 575، وطلاب 200، وبدون مؤهل 719، ومهن أخرى 1140، و516 غير محددى المؤهل.