Video brings together all the techniques for recording and restitution of moving images with or without sound, in an electronic medium and not of photochemical kind. The TV picture is a series of line scans, from the top, and ending at the bottom of the screen. In the early days of television, the quality of phosphorescent tube elements was poor. Thus, online videos and games beam sweeping the bottom of a screen, the top disappears, resulting in a flickering, strongly felt by the human eye at 25 Hz or 30 Hz.
The challenge was to create a single signal encompassing three different information, and should not be mixed prior to treatment by the receiving station. The challenge was also to maintain full compatibility with the black and white positions still present in homes. Researchers are worked in order to create a video signal including red, green, blue, and black and white in the same "pipe" without them mingle.
The cameras, which function as an inverted TV also adopted this interlacing scan. As regards, the first half of an image, a 1st shot defines all the odd lines, and one half frame, a second shooting defines the even lines. The important thing to understand here is that two shots are distant in time (half image).
And even if these two shots are complementary to a spatial point of view (the two scans complement inside the frame), these two shots do not display the same content! If a subject moves in a field, it will have a different position on each of two fields: one then has a zigzag effect on each frame.
This problem is partially solved by means of a birefringent crystal blades that spread out the details by splitting light rays. This results in a loss of definition, which gives the PAL and SECAM systems vertical resolution multiplied by 0.7 (Kell factor), which is not actually that of approximately 400 lines. When the display is not interlaced, the term progressive applies.
This is the shooting mode selected for films shot in HD TV or D cinema to be transferred and projected on 35mm. 25 progressive (25p) then give the camera an exposure time of 1/25 of second, which is too long in terms of temporal resolution. Preference is given limited integration frames 1:50 s (electronic shutter) time.
Analog video standard across the world include NTSC, PAL and SECAM. PAL or SECAM standards have no relationship with the scan of an image, these standards only allow you to add color to black and white images. In the early days of television, only the luminance defines the image by a number of horizontal dots and also by three factors shade of gray.
To remain compatible with black and white, the company carefully avoided RGB, and naturally selects a format containing the Y, plus information conveyed by two chrominance signals U and V (also known as Cr and Cb). These components are connected by formulas U = R - Y and V = B - Y, where Y = + 0,30R 0,59V 0,11B + (the coefficients being different according to the coding used). This transformation from RGB to YUV is called mastering. Metal stamping is a simpler coding operation that generates no degradation, while offering the advantage of compatibility Y.
The challenge was to create a single signal encompassing three different information, and should not be mixed prior to treatment by the receiving station. The challenge was also to maintain full compatibility with the black and white positions still present in homes. Researchers are worked in order to create a video signal including red, green, blue, and black and white in the same "pipe" without them mingle.
The cameras, which function as an inverted TV also adopted this interlacing scan. As regards, the first half of an image, a 1st shot defines all the odd lines, and one half frame, a second shooting defines the even lines. The important thing to understand here is that two shots are distant in time (half image).
And even if these two shots are complementary to a spatial point of view (the two scans complement inside the frame), these two shots do not display the same content! If a subject moves in a field, it will have a different position on each of two fields: one then has a zigzag effect on each frame.
This problem is partially solved by means of a birefringent crystal blades that spread out the details by splitting light rays. This results in a loss of definition, which gives the PAL and SECAM systems vertical resolution multiplied by 0.7 (Kell factor), which is not actually that of approximately 400 lines. When the display is not interlaced, the term progressive applies.
This is the shooting mode selected for films shot in HD TV or D cinema to be transferred and projected on 35mm. 25 progressive (25p) then give the camera an exposure time of 1/25 of second, which is too long in terms of temporal resolution. Preference is given limited integration frames 1:50 s (electronic shutter) time.
Analog video standard across the world include NTSC, PAL and SECAM. PAL or SECAM standards have no relationship with the scan of an image, these standards only allow you to add color to black and white images. In the early days of television, only the luminance defines the image by a number of horizontal dots and also by three factors shade of gray.
To remain compatible with black and white, the company carefully avoided RGB, and naturally selects a format containing the Y, plus information conveyed by two chrominance signals U and V (also known as Cr and Cb). These components are connected by formulas U = R - Y and V = B - Y, where Y = + 0,30R 0,59V 0,11B + (the coefficients being different according to the coding used). This transformation from RGB to YUV is called mastering. Metal stamping is a simpler coding operation that generates no degradation, while offering the advantage of compatibility Y.
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