Television systems can be found in almost all households in the whole world. As of today, television already comes in many forms: liquid crystal display, plasma, light-emitting diodes, cathode ray tubes. Furthermore, even in the advent of high-speed video streaming, televisions still top the list for the equipment used for entertainment. Its development started with the idea of moving pictures. With the use of the knowledge that our eye tends to react to afterimages created by any object that moves so fast, frames are made to be fast enough such that the eye wouldn’t notice that what it is actually seeing is a series of pictures. Nevertheless, modern televisions use interlaced scanning. Interlace scanning is characterized by a vertical scan for all odd lines first down to the bottom and doing a vertical re-trace and other vertical scan, with the even lines this time.

In the past, televisions are only monochrome, that is images appear in shades only, from white to black. With the advent of electron beams and lasers plus the research on eye sensitivity to green light, colored television became feasible. They work by firing concentrated electron beams to the pixels(picture element) of the screen. The pixel consists of three colors: red, blue and green. With the use of the fact that the eye can only track up to certain speeds, a wide variety of colors is possible to achieve. However, it has the initial drawback of how to transmit images with the color precision it requires. This was given the solution by compression, that is discarding some of the data. Quality is not degraded since as said previously, the eye is more sensitive to changes in green light, which means changes in red or blue is not noticed as much as changes in green, and thus, it was alright as long as the compressed data has enough color information to deceive the eye.

Posted 2010-12-14 and updated on Dec 14, 2010 6:52am by crisd

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