A. How to identify
1, to make a connection to the light emitting diode 3 V dc power, better use the battery production. I use the two button batteries, put them in a small plastic pipe and drawn two of the probe as anode and output, which made directly into a tail with switch, when using, positive and negative probe contact with light emitting diode negative of corresponding pins, press and hold the switch of the tail, glowing tube to electric glow.
2, the second, with photoconductive resistance and digital multimeter combined into simple metering device, the photoconductive resistance out two thin wire connected directly in the digital multimeter two pens and, on 20 K multimeter gear position (as the photoconductive resistance and decide, as far as possible the reading to accurate), note that the actual measured value is photoconductive resistance of the resistance, so, the more light on the smaller the value.
3, in a LED light emitting diode, by the above 3 V dc to light, light is close to the head and live connection good photoconductive resistance of photographic surface, at this time, a multimeter reading appear to distinguish the brightness LED light.
Second, brightness identify level, it is to point to the human eye can tell if the images from the most black to white brightness level between the most. Display of gray level some very high, can reach 256 level even level of 1024. But because of the sensitivity of the human eye brightness is limited, and can't fully recognize these gray level. That is maybe a lot of gray eye look adjacent levels is the same. And eyes distinguishing ability each different. For the display, the identification of the human eye level nature is the more the better, because, after all, is displayed image to show. The human eye can identify the level of brightness of more more, means that the space is larger screen color, rich color to show the potential of the bigger also. Brightness levels can be identified with special software to test, general screen to 20 class above even better level.
