Igor is going to install AHD system video surveillance in your grocery store. He knows that the system usually contains several megapixel cameras and one recorder, but he cannot decide which cameras to take: 1.3 megapixels or 2 megapixels. Semyon is with us Sales Representative security and video surveillance systems. His company offers a wide range of megapixel security cameras with different resolutions. He usually recommends a high-definition video surveillance system to his customers, simply because he knows its features better, and this is more profitable for the seller. You probably have similar questions when choosing CCTV cameras. In this article, we are going to provide you with comprehensive information for choosing CCTV cameras.
1. What is a high definition security camera?
All image formats with a resolution of 1280x720 or higher are considered High Definition (HD). In the modern world of video surveillance, there are two directions: analog and digital. Accordingly, there are analog and network (IP) HD cameras. Resolution 960H (NTSC: 960x480) is not classified as HD. Current HD resolution formats include: 1.0 megapixel (720p), 1.3 megapixel (960p), 2 megapixel (1080p), 3 megapixel, 5 megapixel, 8 megapixel (4K UHD), 12 megapixel, 33 megapixel (8K UHD) .
Typically, HD network cameras provide several best quality images than analog HD cameras of the same resolution (eg 720p).
Recently, one of our customers reported that he installed a video surveillance system on 720p AHD cameras (the manufacturer stated 1000TVL) and was not satisfied: the image quality of these 720p AHD cameras turned out to be even worse than that of the old 960H cameras. Why this happened, we will tell in the fourth part of the article.
2. Benefits of high definition
Compared to standard definition, HD technology has increased the detail of the image. Image quality is further enhanced by various enhancement technologies such as progressive scan, 2D/3D dynamic noise reduction, wide dynamic range (WDR), etc. In short, HD delivers superb picture quality. A typical 960H analog camera gives a resolution of 960H/WD1, which is 960x480 pixels (for NTSC) or 960x576 pixels (for PAL). After the signal has been digitized in the DVR or Hybrid DVR, the image will consist of a maximum of 552960 pixels (0.5 megapixels).
A high definition camera can cover a much wider area than a regular camera. Take for example a 12-megapixel panoramic camera with a "" type lens fish eye"" with 360 degree viewing angle. With a built-in 12MP image sensor and ePTZ (Virtual Pan/Tilt/Zoom) and split image capability, it can replace multiple conventional CCTV cameras at once, greatly reducing installation costs and maintenance fees.
Excellent compatibility is another advantage of HD. Whether you shop online or go to local electronics stores, you have noticed that all TVs, camcorders and digital cameras support HD 1080p (FullHD). Accordingly, if you want this equipment to work with your CCTV system, you should choose a CCTV system that supports 1080p. Also, we understand that 4K is the current trend, it is logical to expect 4K UHD video surveillance system to become popular in the future.
3. Various HD resolution formats
High-definition IP cameras are at the forefront of video surveillance systems. They can provide higher quality video with greater image detail and wider coverage than standard definition cameras. You can choose the right format of network (IP) cameras according to your requirements. For example, for face recognition or license plate recognition applications, choose 1080p or higher megapixel network cameras. To find out the resolution of a particular HD format, refer to the following table:
| Format | Resolution (in pixels) | Aspect Ratio | Scan |
| 1MP/720P | 1280x720 | 16:9 | progressive |
| SXGA/960P | 1280x960 | 4:3 | progressive |
| 1.3MP | 1280x1024 | 5:4 | progressive |
| 2MP/1080P | 1920x1080 | 16:9 | progressive |
| 2.3MP | 1920x1200 | 16:10 | progressive |
| 3MP | 2048x1536 | 4:3 | progressive |
| 4MP | 2592x1520 | 16:9 | progressive |
| 5MP | 2560x1960 | 4:3 | progressive |
| 6MP | 3072x2048 | 3:2 | progressive |
| 4K Ultra HD | 3840x2160 | 16:9 | progressive |
| 8K Ultra HD | 7680x4320 | 16:9 | progressive |
4 Choosing HD CCTV Camera
What else besides image resolution should be considered when choosing network HD cameras? Here we will share information on how to choose the right HD cameras from an installer's point of view.
Low illumination
As you know, a CCTV camera does not work like a consumer camera - a CCTV camera cannot use flash when capturing an image / video. If the camera has poor performance in low light, its use is limited. When working in low light conditions, such a camera "blinds", despite its very high resolution.
High resolution is a double-edged sword: the sensor manufacturer does not have the ability to increase the die area indefinitely, so increasing the resolution is associated with a decrease in the size of the pixel itself for the same sensor die sizes (usually 1/3""), so there is less light per pixel , resulting in a decrease in sensitivity as the resolution (megapixels) increases.
Currently, the optimal value for most areas of video surveillance is a resolution of 2MP (1080p/FullHD), it is for this resolution that most of the sensors from the Low Illumination series exist.
Video delay (Time lag)
All network (IP) surveillance cameras have some latency compared to real time, and the cost or quality of the camera is not the determining factor for this delay. For example, for the same 720p image, the video delay time for some cameras is 0.1s, and for some other network cameras, this time may be 0.4s, and even more than 0.7s. Why is the video delay time different? Unlike an analog camera, a network camera compresses the video (a process called encoding), and the user device decodes the video for display, resulting in video delay. Generally, the shorter the latency, the better the image processor's capabilities. This means that you need to select a network camera with the lowest video latency.
Heat dissipation
When the security camera is in operation, it generates heat, especially when the infrared light is turned on at night. This rule is true for any CCTV camera. Excessive heat generation increases the chance of overheating and damage to the camera. When choosing megapixel cameras, pay attention to:
Choose a camera with lower power consumption. Low power consumption means the camera saves power, generates less heat. back side A: In winter, a camera with low heat generation may freeze (usually this concerns the IR filter), and also low consumption means that weak IR illumination is installed, this should also be taken into account.
Consider using a camera with enhanced performance in low light (no infrared or other artificial lighting). Such a camera in low light conditions can capture images even in the dark (> 0.009 - 0.001 lux).
Choose a camera with a case with good heat dissipation. A metal case is preferable to a plastic one. To ensure reliable performance, the elite series network cameras use a finned heatsink on the body to maximize heat dissipation, which greatly helps the camera to ensure reliable performance.
Price
""High price = this high quality"" - in most cases this rule is true. Based on research reports, the consumer often believes that a higher price of a product indicates a higher level of quality. But price isn't the only indicator of good quality, especially when buying "Made in China" products. I have been working in the video surveillance industry for over five years and I can say that end users, integrators and installers can get high quality products from Chinese suppliers/manufacturers at a very competitive price. High-end cameras may have a unique body design, offering special features not found in other products.
Technical support
In conclusion, I want to say that network cameras must also have a good technical support. While IP cameras are becoming easier to set up and operate, end users may encounter technical issues that require outside help. Faced with such a problem, you will receive technical support from us within 1-2 days, which is quite acceptable. It is precisely because of this that I personally do not advise buying CCTV cameras on Aliexpress, since in the future you are unlikely to receive technical support from sellers online support.
Megapixels vs. TV lines
| Device type | TVL/Megapixels | Final resolution NTSC | Final resolution PAL | Megapixels NTSC | Megapixel PAL |
| SONY CCD analog matrices | 480TVL | 510H*492V | 500H*582V | ≈0.25 megapixels | ≈0.29 megapixels |
| 600TVL | 768*494 | 752*582 | ≈0.38 megapixels | ≈0.43 megapixels | |
| 700TVL | 976*494 | 976*582 | ≈0.48 megapixels | ≈0.56 megapixels | |
| SONY CMOS analog matrices | 1000TVL | 1280*720 | ≈0.92 megapixels | ||
| IP cameras and IP recorders | 720P | 1280*720 | ≈0.92 megapixels | ||
| 960P | 1280*960 | ≈1.23 megapixels | |||
| 1080P | 1920*1080 | ≈2.07 megapixels | |||
| 3MP | 2048×1536 | ≈3.14 megapixels | |||
| 5MP | 2592×1920 | ≈4.97 megapixels | |||
| Analog recorders | QCIF | 176*144 | ≈0.026 megapixels | ||
| CIF | 352*288 | ≈0.1 megapixels | |||
| HD1 | 576*288 | ≈0.16 megapixels | |||
| D1(FCIF) | 704*576 | ≈0.4 megapixels | |||
| 960H | 928*576 | ≈0.53 megapixels | |||
By the number of megapixels, you can accurately determine the resolution. To do this, look at the table below. And then we'll figure out what's what.
- One megapixel contains one million pixels. The resolution of an image is determined solely by the number of pixels it consists of.
- As a rule, along with the increase in resolution, the detail of the picture also increases. However, additional factors such as noise reduction, as well as ISO settings and focusing, also come into play here. In itself, a large number of megapixels does not guarantee high image detail.
- In addition, amateur photographers in most cases cannot reap additional dividends from ultra-high resolutions. Modern Full-HD monitors, for example, offer a resolution of only 1920x1080 (that is, a little more than 2 megapixels). Separate details here will become visible only when you zoom in on the image.
- For those who want to print their photos, on the contrary, more megapixels can be very useful. In this case, you still have room to crop photos and print some specific fragments of them without serious loss in quality.
For the amateur photographer: 7 megapixels is enough
Canon PowerShot A710 IS with 7 MP Amateur photographers should also be able to edit their work without too much trouble. That is why you should think about a small "buffer". For printing, 5 megapixels will be enough. Therefore, giving preference to 7 megapixels, you will not be mistaken.
- This will allow you to take photos with a resolution of approximately 3072x2304 pixels. Thus, you will have enough “wiggle room” to cut off unnecessary objects at the edges of the frame or enlarge certain parts of the image. In this case, there should not be a noticeable deterioration in the quality of the picture.
- With this resolution, you can even print your photos without any problems: prints in the size of a postcard (10x15 cm) or even the size of an A4 sheet will look quite clear. Only when printing posters (for example, A3 size) may there be a slight blur.
- With an "average" resolution of 7 megapixels, the files with each individual image will be of medium size: in uncompressed form, the picture will take about 20 MB on the memory card. In JPEG format, one picture will require only 4 MB of disk space. For comparison: at a resolution of 12 megapixels, an uncompressed photo "weighs" already 35 MB.
- The cost of the corresponding cameras starts from 4 thousand rubles.
For lovers of details: 12 megapixels and more
Canon Ixus 255 HS with 12 megapixels Who really wants to capture every detail of the world around him, he may well resort to using a camera with a large number of megapixels:
- Starting from 12 megapixels, you can scale the resulting images in a fairly wide range without loss of quality. Nice fun, but in the end, for most images, it remains unclaimed.
- In addition, here you will have to pay more attention to other factors such as noise reduction or focusing speed. Which cameras combine these qualities well, you will learn from our rating.
- Due to the high cost of the corresponding cameras, you should first think carefully - do you really need a large number of megapixels? Cameras with a resolution of 20 megapixels or more, even among professional photographers, do not have a special priority.
Artem Kashkanov, 2016
Since the advent of digital photographic equipment, a kind of "megapixel race" has been going on between different manufacturers, when new model The camera invariably receives a matrix of more and more resolution. The pace of this race changes from year to year - for quite a long time the "vertical" limit for cropped DSLRs was 16-18 megapixels, but then once again some innovations were introduced into production and the resolution of cropped cameras is approaching 25 megapixels.
To begin with, let's remember that pixel- this is a basic element, a point, one of those from which a digital image is formed. This element is discrete and indivisible - there are no such concepts as "millipixel" or 0.5 pixels :) But there is a concept megapixel, which is understood as an array of pixels in the amount of 1,000,000 pieces. For example, an image of 1000*1000 pixels has a resolution of exactly 1 megapixel. The resolution of the matrices of most cameras has long exceeded the mark of 15 megapixels. What did it give? When permission digital cameras there were 2-3 megapixels, each extra megapixel was a really serious advantage. Now we are witnessing a paradoxical situation - the declared resolution of matrices of amateur DSLRs has become such that it makes it possible to make prints of acceptable quality in almost A1 format! While most amateur photographers rarely print photos larger than 20 by 30 cm, 3-4 megapixels is enough for this.
Is it worth changing the old camera for the same in terms of functions, but "more megapixel?"
Take for example two cameras - a "simple" amateur Canon EOS 1100D and "advanced" Canon EOS 700D. The first has a matrix resolution of "only" 12 megapixels, the second has "whole" 18 megapixels. The difference is 1.5 times. The first thought that many amateur photographers have is something like this - "Changing 1100D to 700D, I will get 1.5 times better detail! Now absolutely all the nuances will be visible in the photographs - I missed this so much with my old camera!". This setting is actively supported by advertisers. The amateur photographer, having convinced himself that he absolutely needs a new camera, breaks the piggy bank and goes to the store.
And let's take a calculator and calculate what the real increase in photo resolution will be when moving from 12 to 18 megapixels. The 18-megapixel sensor of the same 700D gives an image width of 5184 pixels, while the maximum image width of the 12-megapixel 1100D is 4272 pixels (data taken from specifications camera). Divide 5184 by 4272 and get a difference of only 21%. That is, with an increase in the resolution of the matrix by 1.5 times, the photograph increases in size by only 1.21 times. If you depict this graphically, you get such a comparison.
The difference is surprisingly small! It turns out that the differences between 12 and 18 megapixels are not so significant. Conclusion - rumors about the significance of the increase in megapixels are greatly exaggerated. Going from a 12- to 18-megapixel device (or from 18- to 24-megapixel) just in the hope of getting a significant increase in detail in photos is falling for the bait of marketers.
The growth of megapixels in some cases reduces sharpness even when using good optics!
It would seem - it generally looks like nonsense! However, let's not rush to conclusions... It is logical that with the growth of megapixels while maintaining the size of the sensor, the area of each individual pixel decreases. You may know that a decrease in the area of a pixel leads to a decrease in its real sensitivity, and, consequently, to an increase in the level of noise (purely theoretically). However, due to the constant improvement of signal processing technologies and algorithms, new matrices, even despite a noticeable decrease in pixel area, have a very low noise level. But danger may lurk from a completely different direction...
I have already talked about things like diffraction. Without going into details, let me remind you that this is the property of a wave to go around an obstacle, slightly changing direction. When a beam of light passes through a narrow hole, this beam tends to be sprayed, as it were, like a spray (may physicists forgive me for such a comparison :)
In our case, the aperture (diaphragm hole) acts as a hole. The more the diaphragm is clamped, the more the spray is "sprayed" at a greater angle. As a result, a "perfectly clear" point after passing through the aperture turns into a blurry spot. The smaller the aperture diameter, the stronger this blur. And now let's add a small piece of a matrix with pixels to this picture and try to imagine approximately what this "perfectly clear" point will look like in the photo...
Naturally, the above illustrations do not claim to be absolute accuracy; many nuances are not taken into account - at least the fact that when forming an image, neighboring pixels are interpolated and much more. The bottom line is to show that as the pixel area decreases, the working range of aperture numbers decreases. If the matrix has a very high resolution, you should not clamp the lens aperture too much, as this will lead to the appearance of diffraction blur. Matrices with a small number of megapixels allow you to clamp the aperture almost to f / 22 and there is no particular blurring.
Bought a modern carcass? Take care of good optics!
The resolution of the matrices of most modern amateur cameras with interchangeable lenses is between 16 and 24 megapixels. Over time, this range will inevitably shift towards larger values. As a rule, at the same time, the optics that come with the camera are also improved. Although modern whale lenses have significantly improved in quality, they are still "compromise" options. They are most often not capable of drawing a picture in all the nuances for capturing on a 24-megapixel matrix (or they are capable, but in a very narrow range of settings, for example, only in the range of 28-35 mm at aperture 8). If you are looking for an uncompromising option, you will need high-quality and, accordingly, expensive optics. The cost of a lens that is similar to a whale lens in functionality, but has a better resolution, is several times higher than the cost of a whale lens:
Widget from SocialMartBy the way, it is not a fact that the "advanced" version will be guaranteed to "draw" the picture - perhaps the lens was designed at a time when they did not know about matrices with such resolutions. For the same reason, it is not recommended to use kit lenses from very old cameras. I had the experience of using an old kit lens from Canon EOS 300D (6 megapixels) on a 550D (18 megapixels) - once I took a friend to play for the evening. The old 18-55 did not shine with picture quality at 300D, but at 550D it just killed on the spot! It seems that there was no sharpness anywhere.
By the way...
Fixes(i.e. prime lenses) are a great alternative to budget zooms. They will come in handy if the kit lens does not provide the desired detail, but there is no extra $ 1000-1500 to buy a "cool" lens. The most popular fixes are "fifty kopecks" (50 mm), or rather their younger versions with f / 1.8 aperture. At a cost comparable to a whale lens, they significantly outperform it in image quality, but have less versatility - you have to pay for everything.
Pocket soap dish with 20 megapixels - insanity over the edge!
Sadly, there will soon be no other choice. Majority compact cameras have a 1 / 2.3 "matrix, that is, approximately 6 * 4.5 mm - 4 times smaller than that of a "cropped" camera and 6 times smaller than that of a full-frame camera. The resolution is, as a rule, not less than 20 megapixels. It's not hard to imagine how ridiculously small each pixel is, the miniature soap lens has a very small aperture, which increases diffraction blur, resulting in a very "soft" picture when viewed at 100%.
On the left - 100% crop made by a 16-megapixel Sony TX10 soap dish with a 1 / 2.3 "matrix. On the right, for comparison - a similar view taken on a DSLR. Please note that the picture of the soap dish looks very dirty - there is no real detail, there is only software an attempt to refine the outlines. And this is in the center of the frame! At the edges of the frame, the detail is reduced even more and often looks like a misunderstanding:
And so removes the majority of modern compact soap dishes. For example, here, which shows 100% crops from the Panasonic DMC-SZ1 camera (toward the end of the article). The question is - why put matrices with such a high resolution in such devices? These megapixels have no practical value, but from the point of view of marketing it sounds very convincing - in a matchbox-sized camera there are as many as 20 megapixels.
So how many megapixels should a camera have?
We return to the main issue to which the article is devoted. It all depends on the type of camera, the size of the matrix and the capabilities of the optics. Personally, I think a reasonable number of megapixels is:
- For devices with interchangeable lenses with a kit lens - about 12 megapixels. With a higher resolution of the matrix, the "working" range of focal lengths and apertures narrows. If you want to get the most detailed image - try not to shoot at the "extreme" focal lengths, set the aperture to 8.
- For devices with interchangeable lenses with fixes or professional zooms, there is no such explicit limitation, the main thing is that the lens can draw all these megapixels. The absence of a low-pass filter gives a certain advantage, but there are a number of disadvantages - we'll talk about them a little lower. and even with the growth of megapixels, the maximum "working" f-number decreases. Try not to shoot in normal conditions with an aperture greater than 11-13 - you will notice a decrease in sharpness due to diffraction blur.
- For soap dishes with a matrix of 1 / 1.7 "and less, a reasonable limit is 10-12 megapixels. Anything more is a marketing ploy that has nothing to do with detailing.
What characteristics of the matrix are more important than the number of megapixels?
First, the physical size of the matrix. As already mentioned above, 20 megapixels on a 1 / 2.3 "matrix and 20 megapixels APS-C or FF are completely different things. Large sensors always provide better color reproduction, a wider dynamic range and richer hues than smaller ones.
Secondly, the structure of the matrix plays a role. The vast majority of modern cameras have a "Baer" matrix with a smoothing low-frequency filter. One image pixel is formed by interpolating a group of 2*2 matrix pixels (2 green, 1 red, 1 blue). The low-pass filter "blurs" the picture a little, but prevents moire from appearing on objects with a regular repeating pattern (for example, fabric). AT recent times there is a tendency to abandon the low-pass filter in Bayer matrices. Moiré is suppressed by the firmware of the camera.
It is worth noting also X-Trans matrices (used in Fujifilm cameras), which have a more "chaotic" arrangement of RGB color sensors compared to the "baer", they use groups of 6 * 6 matrix pixels for interpolation - this eliminates the formation of moiré and allows you to do without a low-pass filter, which, as already mentioned higher improves image detail.
In the end, the novelty of technology and its class play a role. No matter how perfect the matrix of the camera is, the processor and the in-camera software that processes the signal received from the matrix play an equally important role. As a rule, expensive high-end equipment with the same filling (matrix-processor) as amateur cameras gives better picture quality - a slightly larger dynamic range, a slightly larger working ISO. The manufacturer does not disclose the reasons for these differences, but it is easy to guess that the main reason is intracameral software. It often happens that the younger and older models have the same matrices, but the picture quality is different. This is explained by the fact that for cheap models, the signal processing is carried out according to a more truncated algorithm, so they lose out to older models in picture quality. But this loss is really noticeable only in difficult lighting conditions, for example, when shooting at ultra-high ISO.
The race for megapixels has gradually moved from digital photography to IP video surveillance. Our customers are increasingly asking for cameras of 3, 4, 5 megapixels and even higher. Most of them are absolutely sure that the higher the resolution, the more megapixels the camera has, the better it will show, the higher the frame detail will be. Manufacturers, to please consumers, produce cameras with high resolution, 12 megapixel IP cameras, which are now fashionable in 4K format, are already being sold with might and main.
We decided to find out - does the video quality of IP cameras really increase with an increase in megapixels? Is it worth it to pay extra for high resolution cameras, NVR processing power, high network bandwidth and terabytes of disk space required for such high resolution. We have selected from stock several cameras with different resolutions - from 1 to 5 megapixels. We also ordered several expensive 5 - 8 MP IP cameras from manufacturers for this test. Here's who came to us for testing.
We gave preference to outdoor IP cameras with a fixed lens, because they do not need to be adjusted and flaws in the tedious adjustment of varifocal lenses will not affect the quality of the video image. True, we did not find 5-megapixel cameras with a fixed lens and tested 5MP varifocal cameras. We installed all the cameras in the same place and aimed at the opposite wall, where we have several self-made "test tables" hanging.
Let's see what we got. All snapshots of frames were taken through the web interface of the cameras using the IE browser and the ability to save a freeze frame built into each camera. In the table below, we have placed a reduced frame up to a resolution of 640x480 (or 640x360 if the camera has a widescreen matrix with an aspect ratio of 16:9), as well as a crop (cutout from the frame) with a resolution of 200x360 pixels. It more clearly shows the quality of "drawing" small details of the image - in particular, the letters on the Sivtsev table (a table for checking eyesight).
To view a full-size frame from an IP camera, click on its reduced copy in the table.
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1 MP IP camera: Space Technology ST-120 IP Home, resolution 1280x720, 1/4 matrix, 3.6 mm lens |
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1 MP IP camera: Polyvision PN-IP1-B3.6 v.2.1.4, resolution 1280x720, 1/4 matrix, 3.6 mm lens |
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1.3 MP IP camera: MATRIXtech, resolution 1280x960, 1/3 matrix, 3.6 mm lens |
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2 MP IP camera: Space Technology ST-181 IP Home, resolution 1920x1080, 1/3 matrix, 3.6 mm lens |
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2 MP IP camera: MATRIXtech MT-CW1080IP20, resolution 1920x1080, matrix 1/2.8, lens 3.6 mm |
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3 megapixel resolution. IP camera: Dahua IPC-HFW-1300S-0360B, resolution 2048x1536, 1/3 matrix, 3.6 mm lens |
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4 megapixel resolution. IP camera: Dahua IPC-HFW-4421EP-0360B, resolution 2560x1440, 1/3 matrix, 3.6 mm lens |
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5 megapixel resolution. |
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5 MP |
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>What we noticed when comparing these shots:
- Cameras have different aspect ratios. IP cameras with a resolution of 1, 2, 4 megapixels have a widescreen frame with a ratio of 16:9. And cameras with a resolution of 1.3, 3 and 5 megapixels - 4:3. Those. the latter have a larger vertical viewing angle. This is very important for those cameras that will "look" at the object at an angle from top to bottom. For such cameras, there will be less dead zones under the camera both near and far. It is interesting to note that in relation to the 4MP camera, the 3MP camera not only has a larger vertical viewing angle, but also the resolution: 1536 versus 1440 pixels.
- Cameras have a different viewing angle, and it depends not only on the lens, but also on the size of the matrix. Budget IP cameras with a 1/4 matrix and a standard 3.6mm lens have a horizontal viewing angle of no more than 60°. But the 5MP IPEYE camera with a 1 / 2.5 matrix has a wide viewing angle both vertically and horizontally (more than 110 °). True, the lens in the shortest focus has a distance of 2.8mm.
- Well, the most important thing we wanted to pay close attention to is resolution. If you carefully examine all the frames, you will notice that, undoubtedly, as the resolution (megapixels) increases, the detail increases. But NOT PROPORTIONATELY! Not colossal. A 4MP camera in relation to a 2MP camera does not improve the picture by 2 times. Detail increases slightly. In any case, not a single camera could "cope" with the second line from the bottom of Sivtsev's table. And already the 6th bottom line (the right letters "B K Y") are confidently "read" by both cameras with a resolution of 4 and 2 MP.
Of course, here you need to make an adjustment for a different viewing angle. After all, with an increase in the viewing angle, we seem to be moving away from the scene being shot and the detail worsens. This is especially true for the 5-megapixel IPEYE camera - such a combination of matrix and lens gives too large a viewing angle. And if you make the angle on it the same as for 2MP cameras (about 90 °), then the letters of this table will be read more confidently.
Interestingly, another 5MP IP camera with the same declared parameters (lens 2.8-11, matrix 1/2.5) has a slightly narrower viewing angle in the shortest focus than IPEYE-3802VP. Detailing is approximately at the same level, the picture is somewhat noisier in the dark areas of the frame, although the cost of the BEWARD camera is several times higher. But she has motorized lens and you can control the viewing angle while sitting in front of the computer. A picture with a maximum focus of 11 mm would then look like this:
Maybe someone needs this, given that with each change in the focus of the lens, you either manually or by pressing the "autofocus" button adjust the image sharpness. And it takes from 5 to 20 seconds. But here you can already confidently read the second line from the bottom of the vision test table.
Later, we tested a pair of 2-megapixel IP cameras with a 2.8 - 12mm varifocal lens, as There is an opinion that they show better than "fixes". Here's what we got:
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2 MP IP camera: MATRIXtech MT-CW1080IP40, resolution 1920x1080, matrix 1/2.8, lens 2.8 - 12 mm |
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2 MP IP camera: Hikvision DS-2CD2622FWD-I, resolution 1920x1080, 1/3 matrix, 2.8-12 mm lens |
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As you can see, the result is not much different from the previous one. The detail is almost the same as that of 2MP IP cameras with a fixed lens. Even the expensive 2-megapixel (!) Hikvision camera (the retail price of which in February 2016 was 21,990 rubles) with a viewing angle of 50 degrees set at the factory (and to change it, we had to open the camera, which we absolutely did not want) the readability of the Sivtsev table turned out to be no higher than 5 lines from the bottom.
Perhaps varifocal lenses have greater light sensitivity and IP cameras with them "see" better in the dark, but this is a topic for a completely different test and another article, which we may turn to later. But varifocal lenses have practically no effect on resolution. Moreover, the slightest inaccuracy in the focus setting can lead to disastrous results, and all megapixels will be useless. And whoever has ever set up a varifocal lens on an IP camera will agree with me that it is oh so difficult, given the delay with which the signal from the camera arrives at the monitor.
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5 MP |
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This is the first camera with a 1/1.8 sensor size that we got our hands on. In addition, this camera is capable of streaming at 25 fps at 5-megapixel resolution (2592x1920 px). Others can't do it yet. The maximum they are capable of is 12-15 fps at maximum resolution. The wide field of view of this camera immediately catches the eye. At 3.6mm focus, it is wider than 5MP 1/2.5 sensor cameras with 2.8mm focus. The resolution of the camera from BSP Security is at the level of other 5-megapixel cameras, even a little sharper. At least the contrast of the picture above. However, the situation is slightly overshadowed by the blurring of the left side of the frame. Perhaps we were unlucky and got a camera with a slight skew of the matrix.
And finally, 4K IP cameras with a resolution of 8MP have arrived at our warehouse. This is a hemisphere with a fixed lens DAHUA DH-IPC-HDW-4830EMP-AS. Here is a frame from this camera:
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8 MP IP camera: DAHUA DH-IPC-HDW-4830EMP-AS, resolution 3840*2160, matrix 1/2.5, lens 4 mm |
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To open a frame in full resolution, in the browser, right-click on the picture and select the "open image" menu item.
We did not stop our test on office pictures, we also wanted to see real shots of the street scene. To do this, we aimed our cameras at the nearest parking lot, visible from our window. We did this deliberately in rather difficult light conditions - early twilight. Here's what we got.
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1 MP IP camera: Space Technology ST-120 IP Home, resolution 1280x720, 1/4 matrix, 3.6 mm lens |
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1 MP IP camera: Polyvision PN-IP1-B3.6 v.2.1.4, resolution 1280x720, 1/4 matrix, 3.6 mm lens |
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1.3 MP IP camera: MATRIXtech MT-CW960IP20, resolution 1280x960, 1/3 matrix, 3.6 mm lens |
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2 MP IP camera: Space Technology ST-181 IP Home, resolution 1920x1080, 1/3 matrix, 3.6 mm lens |
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2 MP IP camera: MATRIXtech MT-CW1080IP20, resolution 1920x1080, matrix 1/2.8, lens 3.6 mm |
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3 MP IP camera: Dahua IPC-HFW-1300S-0360B , resolution 2048x1536, 1/3 matrix, 3.6 mm lens |
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4 MP IP camera: Dahua IPC-HFW-4421EP-0360B , resolution 2560x1440, 1/3 matrix, 3.6 mm lens |
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5 MP IP camera: , resolution 2592x1920, matrix 1/2.5, lens 2.8 - 12 mm |
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Perhaps we chose a still too bright part of the day (17.10 - 18.00 in February), but all the cameras with such lighting did an excellent job. True, the 1.3 MP camera MT-CW960IP20 turned out to have a slightly darker picture than the others, which is rather strange, because. the 1/3 matrix should have better photosensitivity in relation to the 1/4 matrix.
As for the detailing of the picture, the situation is similar to the results of testing in the office. Although it increases with the increase in megapixels, but not significantly. Renault's car number was able to read both 4 and 2 megapixel cameras. True last a little worse.
IP cameras with a resolution of 1.3, 4 and 5 megapixels with their wide viewing angle "saw" even the number of our van, on which we carry all these IP cameras)). A 5 MP camera even saw a car standing to the left of the van. The viewing angle is amazing!
In March, we received two more 5-megapixel IP cameras BEWARD and BSP Security for testing. Let's compare how they show on the street.
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5 MP IP camera: , resolution 2592x1944, matrix 1/2.5, zoom lens 2.8 - 11 mm |
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5 MP IP camera: BSP Security, resolution 2592*1920, matrix 1/1.8, lens 3.6 - 11 mm |
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The chambers were tested at the same time (18.00 in mid-March). It is interesting to note that despite the fact that the camera from BSP Security has a wider angle, it has slightly better detail. State. the license plate of the blue Ford is almost readable, which is impossible to do on the frame from the BEWARD camera. The size of the matrix affects - 1 / 1.8 versus 1 / 2.5.
What will we conclude?
- The treacherous pursuit of megapixels is practically useless and only manufacturers (well, what a sin to hide - we, sellers of these IP cameras, recorders and hard drives) benefit from them more profits.
- In the vast majority of cases, 1-2 megapixel IP cameras are sufficient. And if you need better detailing of distant objects, then you need to solve such a problem not by a thoughtless increase in megapixels, but by reducing the viewing angle using a varifocal lens. By this we will "bring" the picture closer to ourselves and will be able to consider everything that we need. And an increase in the number of cameras. Perhaps this solution will be a little more expensive, but it will solve your problem for sure. And perhaps the price of a pair of 2-megapixel cameras with a viewing angle of 50 ° (for example, "fixes" with a 6mm lens) will be less than the price of one 5- or even 4-megapixel camera with an angle of 100 °. But they will give us much more information about the observed territory.
- It should be borne in mind that with an increase in the number of pixels without increasing the physical size of the matrix, it only worsens the sensitivity of the video camera, because. the area of the pixel becomes smaller, and less light hits its surface.
- Real high-quality lenses with optics that allow you to get all the advantages of multi-megapixel matrices cost at least $1000. What can you expect from a $20,000 12-megapixel camera?
- Well, the last thing to remember - with an increase in "megapixel" you will additionally overpay for the processor power of the recorded devices, drives (HDD), network bandwidth and traffic when viewing over the Internet.
P.S. We will continue to test in this way the IP cameras that fall into our hands. Several test samples have already been requested from various suppliers with a resolution of 5 to 12 megapixels. Therefore, visit this page periodically for new information about the megapixel race in IP video surveillance.
P.P.S. If any of the manufacturers or suppliers would like to test their cameras on our "test stand" - welcome to contact us by e-mail: kb063_sobaka_yandex.ru
Modern digital video surveillance cameras provide resolution, measured in millions of pixels per square inch of image, i.e. megapixels.
This high resolution is also provided by HD camcorders that use coaxial cables to transmit uncompressed video streams.
The resolution of 1.3 megapixels is the lowest in the megapixel range, and is 1280x1024 pixels.
Among the advantages of megapixel resolution, which simple analog cannot provide:
- obtaining an image with high detail while maintaining the required field of view;
- the ability to enlarge the image of small objects in order to identify them;
- high speed imaging;
- the ability to adjust the display formats - 4:3 or 16:9.
1.3 MP: IP or HD-SDI?
However, the higher resolution of the generated video implies a much larger volume and the need to store huge data archives. Network cameras in this case are more preferable.
When processing a video stream, the IP camera processor compresses video data using M-JPEG, MPEG-4 and the most advanced H.264 compression codecs. They contribute to a significant reduction in network load and save disk space intended for storing video data.
Support for network cameras technology (PoE) allows you to use fewer cables when creating a system, because. Power is received and signal is transmitted over the same twisted-pair cable via Ethernet.