- published: 18 Jun 2013
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This article discusses moving image capture, transmission and presentation from today's technical and creative points of view; concentrating on aspects of frame rates.
The essential parameters of any moving image sequence as a visual presentation are: presence or absence of colour, aspect ratio, resolution and image change rate.
There are several standard image-change rates (or frame rates) used today: 24 Hz, 25 Hz, 30 Hz, 50 Hz, and 60 Hz. Technical details related to the backwards-compatible addition of color to the NTSC signal caused other variants to appear: 24/1.001 Hz, 30/1.001 Hz, and 60/1.001 Hz.
The image change rate fundamentally affects how "fluid" the motion it captures will look on the screen. Moving image material, based on this, is sometimes roughly divided into 2 groups: the so-called film-based material, where the image of the scene is captured by camera 24 times a second (24 Hz), and the video-based material, where the image is captured 50 or ~60 times a second.
Image file formats are standardized means of organizing and storing digital images. Image files are composed of digital data in one of these formats that can be rasterized for use on a computer display or printer. An image file format may store data in uncompressed, compressed, or vector formats. Once rasterized, an image becomes a grid of pixels, each of which has a number of bits to designate its color equal to the color depth of the device displaying it.
The size of raster image files is positively correlated with the resolution and images size (number of pixels) and the color depth (bits per pixel). Images can be compressed in various ways, however. A compression algorithm stores either an exact representation or an approximation of the original image in a smaller number of bytes that can be expanded back to its uncompressed form with a corresponding decompression algorithm. Images with the same number of pixels and color depth can have very different compressed file size. Considering exactly the same compression, number of pixels, and color depth for two images, different graphical complexity of the original images may also result in very different file sizes after compression due to the nature of compression algorithms. With some compression formats, images that are less complex may result in smaller compressed file sizes. This characteristic sometimes results in a smaller file size for some lossless formats than lossy formats. For example, graphically simple images (i.e. images with large continuous regions like line art or animation sequences) may be losslessly compressed into a GIF or PNG format and result in a smaller file size than a lossy JPEG format.
A film, also called a movie, motion picture or photoplay, is a series of still images which, when shown on a screen, creates the illusion of moving images due to the phi phenomenon. This optical illusion causes the audience to perceive continuous motion between separate objects viewed rapidly in succession. A film is created by photographing actual scenes with a motion picture camera; by photographing drawings or miniature models using traditional animation techniques; by means of CGI and computer animation; or by a combination of some or all of these techniques and other visual effects. The word "cinema", short for cinematography, is often used to refer to the industry of films and filmmaking or to the art of filmmaking itself. The contemporary definition of cinema is the art of simulating experiences to communicate ideas, stories, perceptions, feelings, beauty or atmosphere by the means of recorded or programmed moving images along with other sensory stimulations.
The process of filmmaking is both an art and an industry.