As technology for color television developed, however, engineers had to create a broadcast method that would still allow owners of monochrome television sets to receive a picture. When the NTSC format was first adopted in 1941, there was little discussion of color transmissions. When an NTSC videotape is converted to PAL, black bars are often used to compensate for the smaller screen aspect, much like the bars at the top and bottom of a letterbox or "widescreen" movie. PAL television broadcasts contain 625 lines of resolution, from top to bottom, compared to NTSC's 525. While PAL may have fewer frames per second, it displays more lines than NTSC. More lines usually means more visual information, which results in better picture quality and resolution. NTSC: Which is better?Īnother difference between NTSC and PAL formats is resolution quality. This means that a PAL signal displays at 25 fps, consisting of two sets of 25 alternating lines. Since countries in Europe and Asia often use a 50 hertz power supply, the equivalent PAL lines go out at 50 fields per second. The result for an NTSC television is 30 frames of a complete image, made up of two fields for each frame, appearing every second.
This line alternation happens so fast that it is undetectable to the human eye, much like a film running through a projector. Since most analog televisions use an interlaced system, this means that 30 fields of one type are sent out, along with 30 fields of the other type each second.
The first field accounts for all of the odd-numbered lines on a screen, while the second one includes the even-numbered lines. In the US and countries like Canada and Mexico, electrical power is generated at 60 hertz, so for technical reasons the NTSC signal is also sent out at 60 "fields" per second. The differences between these formats really start with the electrical power system behind the transmissions viewed on a TV.
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