In the video camera circle, the technical indicators in a color page actually cover most of the technical parameters. However, there are several people who dare to say that he knows completely that whether it is a salesperson or an engineering company, the first to get is A coloring page, and most of the color pages are bragging. Only with a little knowledge on the final technical indicators, we will take everyone to do it today. Before clarifying technical indicators, we must first clarify the following: thing:
1, the imaging element is CCD! (Of course there are CMOS), mainly divided into color, black and white; 1/3′′, 1/4′′, 1/2′′ and brand. The difference in size is mainly the sensitivity, which is the minimum illumination, 1/4′′ illumination ratio 1/3′′ difference, the principle is very simple: the same number of photosensitive spots, each point on the 1/4 must be smaller, his light is less, of course, the illumination is poor, the advantage is cheaper, Smaller size, the board can be smaller.Brand: In terms of price, from expensive to cheap, they are Sony, Panasonic, Sharp, A1 (LG).If you use Sony's usual logo "Sony Super-HAD CCD" This is a registered trademark of Sony, or a low-light monogram "Sony Ex-View CCD". In the manufacturing process of CCD, there is a process called "HAD", so no matter which CCD, it can be called "HAD." CCD", but Sony improved the process, thought that the quality of the CCD was better, called "Super-HAD" and registered the name, so only Sony has a so-called Super-HAD CCD, which is often seen on general CCD types. To "1/3 SONY Super-HAD CCD" is this way, it can not be labeled "1/3 Sharp Supe r-HAD CCD" That would be a joke. Ex-view is a proper term for Sony's CCD registration, emphasizing illumination lower than Super-HAD, of course, the price is much more expensive, other features and pins are the same with the original Super-HAD Almost, instead of using SONY, it is only labeled "1/3 Color CCD".
2, pixel PAL system, there 752 (H) x 582 (V), which is the so-called 440,000 pixels, and 500 (H) x 582 (V) is the so-called 250,000 pixels; NTSC system, there are 768 (H) x 494 (V), also known as 380,000 pixels, and 510 (H) x 492 (V) are also called 250,000 pixels. 44 million pixels is called high resolution, and 250,000 is called low resolution, universal solution or Chinese solution. The above-mentioned pixels refer to "effective pixels."
3. Resolution This is more fun. The technical limit of a 25-megapixel camera is about 320. More than a decade ago, Taiwan produced a video camera, probably between 280-300, but compared with Japanese goods. When you get up, you're going to be wrong. What can you do? So the standard 350 line is good, and later there are new companies and South Korea out of it, probably around 300, so the standard 380 good, and in recent years, ** also out, what can I do? So standard 420 is good! Now, all of them are marked 420, and there are also shameless 450, even more puzzling is that whether it is in Taiwan or **, sent to testing, it is actually 420? It's really bizarre! And 440,000 The technical limit is about 480 lines. Generally speaking, China, Taiwan, and South Korea are about 400-450. In the same way, the standard is 480, 500, 520, 550! Each conscience.
Also, the recent popularity of the so-called 520 line, why he said 520 line? Because the main chip with the Sony HQ1 (CXD3172AR), only non-official statement: there are 520 lines, but only Y/C output. Therefore, as long as the HQ1 program, we will mark 520, in addition to irrigation method, 550 and 560 came out, it is estimated that 580 is also there.
4, the minimum illumination of the most simple definition: in the dark room, the camera is facing the measured object, and then slowly dim the light until the display is about to not see the measured object, then the amount of light illumination is the minimum illumination . It's vague enough! In fact, we must consider using a few millimeters of lens, how much light into the camera AGC must be turned off, the video signal is down to how much IRE and so on. Few manufacturers will do this test. The old story came again. For a long time long ago, the standard 1.1Lux (F1.2) that Matsushita and Sony had solved with low resolution, that Taiwan had made it a mark of 0.5, and later it had to mark 0.2, you marked 0.2, and I marked 0.1, he marked 0.05....... That's it.
Also, high-resolution CCD illuminance will be worse than low-resolution, or old saying, the same chip area, one placed 440,000 points, one placed 250,000 points, that big point?
5. Signal-to-noise ratio As long as the power is applied to any circuit, it will generate noise, including the components and the line itself. Of course, the smaller the noise, the cleaner the picture will appear. We use the ratio of the video signal to the noise signal. Of course, the bigger the better, the mathematical formula is 20log (V2/V1), V2 refers to the video signal, V1 refers to the size of the noise, the unit is "dB".
Or the old story, long time ago, Panasonic and Sony's machine noise ratio than the standard 50dB, that Taiwan made it on the standard ... ... hey! Looks like it is relatively poor, embarrassing bragging, then the standard 48 is good, but not Looks good? Modified: "More than 48dB", so "> 48dB" is this way, regardless of the A-Cat dog made by the camera, will be so marked, there is to test? My head gave him!
6, electronic shutter In order to allow the image brightness is correct, we must correctly control the amount of light into the camera, we must adjust the amount of light from the lens aperture and the camera shutter, generally we use the manual lens, the aperture adjustment will not move, If you encounter glare at this time, what should I do? Very simple, before the CCD has not been exposed, the DSP quickly slams the signal on the CCD, that is, when the light is strong, it catches more quickly, when the light is weak, it catches slowly. , Scratch once equivalent to my door SLR camera when the "click" sound, SLR camera is a mechanical shutter, we are electronic, so called "electronic shutter."
According to the DSP specification, the electronic shutter speed is 1/50 second to one hundred thousandth of a second in the PAL system, so everyone has marked this. If the camera is poorly tuned for practical applications, it is less than one hundred thousandth. If the camera looks like a thin layer of fine white yarn in the sun, it is not very clear. That is, the shutter speed is not enough.
If you use an auto iris lens, the amount of light entering the lens is controlled by the lens aperture. At this time, the shutter speed of the camera itself is set at 1/50 second.
7, Gamma compensation What is Gamma? Simple explanation, CRT tube is based on the intensity of the electron beam hit on the screen to determine the resulting brightness, the stronger the stronger the fight, but not 1:1, that is, in the When it is strong, it will not be proportionally bright. This is the characteristic of CRT tubes. Therefore, the video output must be enhanced deliberately at high brightness. This is called Gamma compensation. There is no technology at all, and some cameras will Add a switch, let you choose 0.45 or 1:1, the compensation curve is 1:1 in some bright light environment is also very easy to use (under strong light, non-backlit).
8, backlight compensation What is the backlight compensation, which is related to the shutter speed, for example, when a camera mounted on the ATM, facing the street, in the big sun, the environment is very bright, so the camera shutter speed is of course very Fast, it will not be overexposed, then if someone to withdraw money, face the camera, because the camera is currently mining full metering, basically affected by the environment, the overall is still very bright, in the high-speed shutter, face exposure Insufficient, it is obviously dark, which is the "backlight" of photography mentioned above, that is: the back of a strong light, resulting in the subject underexposure and black.
So the problem lies in the overall exposure. If we only take a part of the screen to measure light, for example, in the middle, the face is in the middle of the screen. At this time, the DSP will detect underexposure and slow down the shutter speed. The face is clear, but because the shutter speed is slow, the background (street) is overexposed and white. Therefore, backlight compensation is based on a specific metering area, adjust the electronic shutter (or automatic aperture), so that the exposure value in the metering area is normal, not in the metering area, regardless of the metering area set by the DSP parameters, Usually take the middle 1/9, or add the bottom 1/3 into a convex font. As for what is "wide dynamic," it will be written separately to talk about it.
9, synchronization system within the synchronization, external synchronization and power synchronization.
Power synchronization: It has already been introduced before and will not be described here. In addition, the AC power supply used by us has three phases, which are 120 degrees different from each other. If the power supply synchronization machines are connected to different phase power supplies, there will be a phase difference that cannot be synchronized with each other. Therefore, a phase adjustment knob is needed to trigger the phases to each other. Adjusted to the same.
Out-of-sync: It is triggered by external steps to throw out the screen. This function is rarely used now.
Internal synchronization: It is the output of 25 pictures per second, regardless of others.
10, AGC
It is the electronic automatic gain, it is the basic function of the camera, some people make the screen look bright, deliberately adjusted very high, so that when the low illumination is very easy to white, so some people simply put a switch here, to be high To be low, come on your own!
11. The following are the connector types that do not matter: C-Mount and C/S Mount. To tell the story, when the camera was originally made, it had to be equipped with a lens. Therefore, an interface standard was adopted: “The pitch diameter is 25.4mm, 32 threads per inch, and the distance from the edge to the CCD is 17.526mmâ€. This is called C interface, camera and lens will be compared to this standard, they can match each other. At that time, there were eight lenses in the lens. Later Panasonic engaged in a five-glass lens, the cost was saved, but the imaging distance was shorter by about five millimeters, which means the lens was closer to the CCD by five millimeters. What to do? Then change the standard, and change the head “from edge to CCD distance 17.526mm†to 12.5mm. No, it's called the C/S interface. Almost all the cameras now use the C/S interface, plus an extension ring from the C/S to C interface.
Automatic aperture: that is, the type of auto iris lens that can be connected, there are currently two: video and direct drive (DC), because the direct drive method has to add a small circuit, some cheap machines simply take Lost, bet you can't afford to buy a DC auto iris lens.
Video output: The standard is 1 Vpp, that is, 1 volt (peak to peak), the standard is such a mark, but often the manufacturers look for a "bright" point, intentionally increase the strength of the question mark, when connecting DVR and wiring It will cause some problems.
Power consumption: Generally, when the camera is at 12V, it is generally between 90-130 mA.
Power: divided into 12VDC, 24VAC, 220VAC three, usually 24VAC is also compatible with 12VDC.
1, the imaging element is CCD! (Of course there are CMOS), mainly divided into color, black and white; 1/3′′, 1/4′′, 1/2′′ and brand. The difference in size is mainly the sensitivity, which is the minimum illumination, 1/4′′ illumination ratio 1/3′′ difference, the principle is very simple: the same number of photosensitive spots, each point on the 1/4 must be smaller, his light is less, of course, the illumination is poor, the advantage is cheaper, Smaller size, the board can be smaller.Brand: In terms of price, from expensive to cheap, they are Sony, Panasonic, Sharp, A1 (LG).If you use Sony's usual logo "Sony Super-HAD CCD" This is a registered trademark of Sony, or a low-light monogram "Sony Ex-View CCD". In the manufacturing process of CCD, there is a process called "HAD", so no matter which CCD, it can be called "HAD." CCD", but Sony improved the process, thought that the quality of the CCD was better, called "Super-HAD" and registered the name, so only Sony has a so-called Super-HAD CCD, which is often seen on general CCD types. To "1/3 SONY Super-HAD CCD" is this way, it can not be labeled "1/3 Sharp Supe r-HAD CCD" That would be a joke. Ex-view is a proper term for Sony's CCD registration, emphasizing illumination lower than Super-HAD, of course, the price is much more expensive, other features and pins are the same with the original Super-HAD Almost, instead of using SONY, it is only labeled "1/3 Color CCD".
2, pixel PAL system, there 752 (H) x 582 (V), which is the so-called 440,000 pixels, and 500 (H) x 582 (V) is the so-called 250,000 pixels; NTSC system, there are 768 (H) x 494 (V), also known as 380,000 pixels, and 510 (H) x 492 (V) are also called 250,000 pixels. 44 million pixels is called high resolution, and 250,000 is called low resolution, universal solution or Chinese solution. The above-mentioned pixels refer to "effective pixels."
3. Resolution This is more fun. The technical limit of a 25-megapixel camera is about 320. More than a decade ago, Taiwan produced a video camera, probably between 280-300, but compared with Japanese goods. When you get up, you're going to be wrong. What can you do? So the standard 350 line is good, and later there are new companies and South Korea out of it, probably around 300, so the standard 380 good, and in recent years, ** also out, what can I do? So standard 420 is good! Now, all of them are marked 420, and there are also shameless 450, even more puzzling is that whether it is in Taiwan or **, sent to testing, it is actually 420? It's really bizarre! And 440,000 The technical limit is about 480 lines. Generally speaking, China, Taiwan, and South Korea are about 400-450. In the same way, the standard is 480, 500, 520, 550! Each conscience.
Also, the recent popularity of the so-called 520 line, why he said 520 line? Because the main chip with the Sony HQ1 (CXD3172AR), only non-official statement: there are 520 lines, but only Y/C output. Therefore, as long as the HQ1 program, we will mark 520, in addition to irrigation method, 550 and 560 came out, it is estimated that 580 is also there.
4, the minimum illumination of the most simple definition: in the dark room, the camera is facing the measured object, and then slowly dim the light until the display is about to not see the measured object, then the amount of light illumination is the minimum illumination . It's vague enough! In fact, we must consider using a few millimeters of lens, how much light into the camera AGC must be turned off, the video signal is down to how much IRE and so on. Few manufacturers will do this test. The old story came again. For a long time long ago, the standard 1.1Lux (F1.2) that Matsushita and Sony had solved with low resolution, that Taiwan had made it a mark of 0.5, and later it had to mark 0.2, you marked 0.2, and I marked 0.1, he marked 0.05....... That's it.
Also, high-resolution CCD illuminance will be worse than low-resolution, or old saying, the same chip area, one placed 440,000 points, one placed 250,000 points, that big point?
5. Signal-to-noise ratio As long as the power is applied to any circuit, it will generate noise, including the components and the line itself. Of course, the smaller the noise, the cleaner the picture will appear. We use the ratio of the video signal to the noise signal. Of course, the bigger the better, the mathematical formula is 20log (V2/V1), V2 refers to the video signal, V1 refers to the size of the noise, the unit is "dB".
Or the old story, long time ago, Panasonic and Sony's machine noise ratio than the standard 50dB, that Taiwan made it on the standard ... ... hey! Looks like it is relatively poor, embarrassing bragging, then the standard 48 is good, but not Looks good? Modified: "More than 48dB", so "> 48dB" is this way, regardless of the A-Cat dog made by the camera, will be so marked, there is to test? My head gave him!
6, electronic shutter In order to allow the image brightness is correct, we must correctly control the amount of light into the camera, we must adjust the amount of light from the lens aperture and the camera shutter, generally we use the manual lens, the aperture adjustment will not move, If you encounter glare at this time, what should I do? Very simple, before the CCD has not been exposed, the DSP quickly slams the signal on the CCD, that is, when the light is strong, it catches more quickly, when the light is weak, it catches slowly. , Scratch once equivalent to my door SLR camera when the "click" sound, SLR camera is a mechanical shutter, we are electronic, so called "electronic shutter."
According to the DSP specification, the electronic shutter speed is 1/50 second to one hundred thousandth of a second in the PAL system, so everyone has marked this. If the camera is poorly tuned for practical applications, it is less than one hundred thousandth. If the camera looks like a thin layer of fine white yarn in the sun, it is not very clear. That is, the shutter speed is not enough.
If you use an auto iris lens, the amount of light entering the lens is controlled by the lens aperture. At this time, the shutter speed of the camera itself is set at 1/50 second.
7, Gamma compensation What is Gamma? Simple explanation, CRT tube is based on the intensity of the electron beam hit on the screen to determine the resulting brightness, the stronger the stronger the fight, but not 1:1, that is, in the When it is strong, it will not be proportionally bright. This is the characteristic of CRT tubes. Therefore, the video output must be enhanced deliberately at high brightness. This is called Gamma compensation. There is no technology at all, and some cameras will Add a switch, let you choose 0.45 or 1:1, the compensation curve is 1:1 in some bright light environment is also very easy to use (under strong light, non-backlit).
8, backlight compensation What is the backlight compensation, which is related to the shutter speed, for example, when a camera mounted on the ATM, facing the street, in the big sun, the environment is very bright, so the camera shutter speed is of course very Fast, it will not be overexposed, then if someone to withdraw money, face the camera, because the camera is currently mining full metering, basically affected by the environment, the overall is still very bright, in the high-speed shutter, face exposure Insufficient, it is obviously dark, which is the "backlight" of photography mentioned above, that is: the back of a strong light, resulting in the subject underexposure and black.
So the problem lies in the overall exposure. If we only take a part of the screen to measure light, for example, in the middle, the face is in the middle of the screen. At this time, the DSP will detect underexposure and slow down the shutter speed. The face is clear, but because the shutter speed is slow, the background (street) is overexposed and white. Therefore, backlight compensation is based on a specific metering area, adjust the electronic shutter (or automatic aperture), so that the exposure value in the metering area is normal, not in the metering area, regardless of the metering area set by the DSP parameters, Usually take the middle 1/9, or add the bottom 1/3 into a convex font. As for what is "wide dynamic," it will be written separately to talk about it.
9, synchronization system within the synchronization, external synchronization and power synchronization.
Power synchronization: It has already been introduced before and will not be described here. In addition, the AC power supply used by us has three phases, which are 120 degrees different from each other. If the power supply synchronization machines are connected to different phase power supplies, there will be a phase difference that cannot be synchronized with each other. Therefore, a phase adjustment knob is needed to trigger the phases to each other. Adjusted to the same.
Out-of-sync: It is triggered by external steps to throw out the screen. This function is rarely used now.
Internal synchronization: It is the output of 25 pictures per second, regardless of others.
10, AGC
It is the electronic automatic gain, it is the basic function of the camera, some people make the screen look bright, deliberately adjusted very high, so that when the low illumination is very easy to white, so some people simply put a switch here, to be high To be low, come on your own!
11. The following are the connector types that do not matter: C-Mount and C/S Mount. To tell the story, when the camera was originally made, it had to be equipped with a lens. Therefore, an interface standard was adopted: “The pitch diameter is 25.4mm, 32 threads per inch, and the distance from the edge to the CCD is 17.526mmâ€. This is called C interface, camera and lens will be compared to this standard, they can match each other. At that time, there were eight lenses in the lens. Later Panasonic engaged in a five-glass lens, the cost was saved, but the imaging distance was shorter by about five millimeters, which means the lens was closer to the CCD by five millimeters. What to do? Then change the standard, and change the head “from edge to CCD distance 17.526mm†to 12.5mm. No, it's called the C/S interface. Almost all the cameras now use the C/S interface, plus an extension ring from the C/S to C interface.
Automatic aperture: that is, the type of auto iris lens that can be connected, there are currently two: video and direct drive (DC), because the direct drive method has to add a small circuit, some cheap machines simply take Lost, bet you can't afford to buy a DC auto iris lens.
Video output: The standard is 1 Vpp, that is, 1 volt (peak to peak), the standard is such a mark, but often the manufacturers look for a "bright" point, intentionally increase the strength of the question mark, when connecting DVR and wiring It will cause some problems.
Power consumption: Generally, when the camera is at 12V, it is generally between 90-130 mA.
Power: divided into 12VDC, 24VAC, 220VAC three, usually 24VAC is also compatible with 12VDC.
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