艺术英语 Unit 13.pptVIP

Digital Photograph With expensive ultra-wide angle lens With normal lens and software Subject: Nature Number: Take a serial photos and more than 3 Notice: Varying weather conditions are also best avoided Divide students into groups according to their theme Invite several students to introduce their arts about the choice of scene With the help of professional teachers, students can identify different photography skills Passage One What Is a Digital Photograph? Pixels-dots Digital photographs are made up of hundreds of thousands or millions of tiny squares called picture elements or just pixels. Like the impressionists who painted wonderful scenes with small dabs of paint, your computer and printer can use these tiny pixels to display or print photographs. To do so, the computer divides the screen or printed page into a grid of pixels. It then uses the values stored in the digital photograph to specify the brightness and color of each pixel in this grid form of painting by number. Controlling, or addressing a grid of individual pixels in this way is called bit mapping and digital images are called bit-maps. Image Size The quality of a digital image, whether printed or displayed on a screen, depends in part on the number of pixels used to create the image. More pixels add detail and sharpen edges. If you enlarge any digital image enough, the pixels will begin to show an effect called pixelization. This is not unlike traditional silver-based prints where grain begins to show when prints are enlarged past a certain point. The more pixels there are in an image, the more it can be enlarged before pixelization occurs. The size of a photograph is specified in two ways by its dimensions in pixels or by the total number of pixels it contains. For example, the same image can be said to have 1800 x 1600 pixels (where “x”is pronounced “by” as in “1800 by 1600”), or to contain 2.88-million pixels (1800 multiplied b