Resolution 3 megapixels in pixels. Megapixel - what is it and how many should there be? What matrix characteristics are more important than the number of megapixels

In Moscow, 3MP cameras are in demand both among commercial firms requiring security shopping facilities, secure places, institutions with high traffic, and among private buyers. Video cameras of 3 megapixels are purchased for street monitoring, guarding a parking lot, a garage, a summer cottage, and working as part of a powerful video surveillance system.

Increasingly affordable prices for cameras with a resolution of 3 megapixels also contribute to widespread demand. Especially big choice configurations and cost can be found in the online store. It is easy to buy a 3-3.2 megapixel video surveillance camera on it, at a price of 2000 rubles with fast delivery directly to the address specified in the order.

There is a choice of different configurations:

• Surveillance camera with a resolution of 3 MP;
• 3 USB camera;
• 3.2 megapixel camera

and other options are available right now at the best possible price. In order for the device to fully meet all the requirements of quality, safety and performance, when choosing, you need to evaluate the technical characteristics.

Here is a sample list of them:

• Shooting angle.
• Possibility of manual, remote control of the lens position, automatic reversal of the lens in the direction of the detected moving object.
• The presence of night illumination, providing normal shooting without any additional lighting.
• Materials of manufacture, strength of the device, protection against moisture, dust, mechanical damage, vandalism.
• Possibility of remote connection to the broadcast via the Internet, remote control of functions and settings.
• The method of mounting the camera on the site, the possibility of self-installation and connection without the help of specialists, following the instructions.
• The exact dimensions and weight of the device without packaging.

All important information indicated on the website of the store. There are also reviews from other buyers, from which one can draw a conclusion about the effectiveness of the selected 3 MP camera model in similar conditions.

The race for megapixels digital photography gradually moved 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 parts images - in particular 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.

What we noticed when comparing these shots:

1. 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.
2. 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.
3. 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 a 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:

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.

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:

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.

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.

5 MP IP camera: , resolution 2592x1944, matrix 1/2.5, zoom lens 2.8 - 11 mm
5 MP IP camera: BSP Security, resolution 2592*1920, matrix 1/1.8, lens 3.6 - 11 mm

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?

1. 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.
2. 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.
3. 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.
4. 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?
5. 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 vendors with resolutions ranging from 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

Artem Kashkanov, 2016

Since the advent of digital photographic equipment, a kind of "megapixel race" has been going on between different manufacturers, when a new camera model invariably receives a matrix of ever greater 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:

By 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 whale lens they significantly surpass 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. Most 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, no less 20 megapixels It's not hard to imagine how ridiculously small each pixel is. The miniature soap lens has a very small aperture size, which increases diffraction blur. As a result, the picture looks very "soft" when viewed at 100% scale.

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). IN Lately there is a tendency to abandon the low-pass filter in Bayer matrices. Moiré is suppressed by the firmware of the camera.

It is also worth noting the X-Trans matrices (used in Fujifilm cameras), which, compared to the "baer", have a more "chaotic" arrangement of RGB color sensors, 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 mentioned above, 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 best quality pictures - a little more dynamic range, a little more working ISO. The manufacturer does not disclose the reasons for these differences, but it is easy to guess that main reason- 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.

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. By 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

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 snapshot 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

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.

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It is noteworthy that even a slight increase in linear resolution is accompanied by a substantial increase in the number of megapixels. It's like calculating area. To double the number of megapixels, it is enough to increase the linear resolution by 41%, and doubling the linear resolution leads to a fourfold increase in the number of megapixels. It is precisely for this insidious property that megapixels are so dearly loved by marketers, because it allows you to present very moderate progress as something revolutionary.

In fact, a twofold increase in the number of megapixels is not a revolution at all, it is just the minimum after which the increase in detail becomes noticeable to most people, and then only on the condition that the detail was limited solely by the number of pixels, and not at all by lens aberrations, misses focusing, camera shake and inept editing. Moreover, the contribution of the matrix resolution to the overall sharpness of the image is rapidly decreasing as the number of megapixels increases. Up to 10 megapixels, this contribution is very significant, from 10 to 20 megapixels is no longer so significant, and at resolutions above 20 megapixels, the quality of optics and the skill of the photographer unconditionally come to the fore.

Is too much megapixels harmful?

In general, no, it is not harmful. I just think it necessary to emphasize that there is not much benefit from it. In my opinion, the only really negative effect associated with increasing the resolution is a proportional increase in the volume of files that quickly fill up memory cards, devour disk space and slow down the computer in post-processing.

It may be objected to me that high-resolution cameras are even more noisy at high ISO values. This is true, but only when comparing images pixel-by-pixel, i.e. at 100% magnification. With an equal scale, the noise level will be approximately the same (with other equal conditions, of course). For example, if a picture taken with a 36-megapixel camera is reduced in Photoshop to 16 megapixels, then in terms of noise level it will practically not differ from a similar picture originally taken with a 16-megapixel camera. In this case, the reduced image may look even somewhat sharper, since image reduction (decimation) to a certain extent neutralizes the loss of sharpness that is inevitable with Bayer interpolation.

Thus, high resolution really allows the camera's sensor to collect more information about the scene being shot and potentially provide better image detail. Another question is, will you be able to use this potential, or will it be embodied only in extra gigabytes occupying your hard drive?

To understand how many megapixels will be necessary and sufficient for you, you just need to remember what end use do you find for your pictures? Do you view them on a computer monitor or maybe with a digital projector? do you print your pictures, and if so, what is the maximum print size? do you share your pictures online? Do you process your shots in any way, or are you satisfied with what comes out of the camera?

Viewing photos on a computer monitor

The most common screen resolution among visitors to my site is 1920x1080 (Full HD), which is about two megapixels. For laptops, the most popular resolution is 1366×768 (WXGA), i.e. one megapixel. Rare visitors use monitors with a resolution of 2560 × 1440 (WQXGA), which is less than four megapixels. There are so few iMacs with Retina displays that they can be ignored.

The conclusion, it seems to me, is obvious: to view photos on the monitor personal computer in most cases, 2-4 megapixels is enough. And this is if the picture is expanded to full screen, and does not huddle in a small window.

Projectors

Mass models of modern digital projectors have a resolution of 1920 × 1080 (Full HD) or even less, which means that it is pointless to try to show the public something more than a couple of megapixels with their help. Projectors with a resolution of 4096×2160 (4K) are simply not affordable for most photographers, but even incomplete nine megapixels is not so much by today's standards.

Printing photos

The resolution of a print, regardless of its size, is usually measured in dots per inch (dpi). For example, when printing at 300 dpi, there will be 300 dots per linear inch (2.54 cm), which corresponds to 118 dots per linear centimeter.

Resolutions below 150 dpi are considered low, 150 to 300 dpi are acceptable, and 300 dpi or more are considered high. High resolution means that the individual dots that make up the image are virtually indistinguishable to the naked eye. Usually prints of moderate size (up to A3 inclusive) are made with a resolution of exactly 300 dpi. For larger prints, a lower resolution may be acceptable.

Much depends on the distance from which you are going to view the picture. Small cards are viewed up close and their resolution should be as high as possible. Large canvases are hung on the wall and admired while standing at some distance, and therefore even a relatively low resolution will not hurt the eye. This also applies to photo wallpapers. Huge billboards that people look at from a distance of tens of meters can be printed at 32 dpi and still look good.

The table below shows how many megapixels are required to capture and then print photos at both 150 and 300 dpi resolution at various print sizes.

When was the last time you printed your photos on A3? Let me remind you that the most popular print size among amateur photographers is A6, i.e. 10×15 cm.

Internet

The internet doesn't like big pictures. Firstly, large photos take a long time to load, and secondly, most people are simply not interested in looking at the microscopic details of other people's pictures. The only exception is specialized photographic forums. As for social networks, then your multi-megapixel images will in any case be reduced when uploading to the server, regardless of your consent, and the decimation quality will not be the highest.

If you send photos to relatives and friends by e-mail, then you need to reduce them, at least for reasons of elementary decency. Who wants to wait for huge files with flowers and kittens to load?

In a word, here you will need literally a couple of megapixels.

Of course, all this applies exclusively to amateur photography and does not apply to images intended for commercial use. It all depends on the specific situation. If the customer by all means demands 20 megapixels - so what? - we will send him exactly 20 megapixels, but whether he really needs them is no longer our concern.

Image processing

When editing photos in Adobe Photoshop or another graphic editor, some excess resolution is not only tolerable, but also highly desirable. Firstly, many sims need to be cropped, i.e. in cropping the edges, and it's good when you have the opportunity not to save pixels. Secondly, competent reduction of the image - The best way hide or at least minimize image defects such as noise, chromatic aberration, moderate shaking, interpolation artifacts, etc. In other words, a photo taken at high resolution and then scaled down almost always looks better than one originally taken at low resolution.

However, it should be noted that the resolution modern cameras so large that there is almost always a supply of megapixels that can be sacrificed in editing.

Conclusion

You and I have talked for too long about something that should not have been talked about at all. Let's finally sum up.

A dozen megapixels will be enough to satisfy the needs of the vast majority of amateur photographers, although even this number seems somewhat excessive. A rare enthusiast will be able to fully realize the potential of twenty megapixels, but such people usually know what they want. The same photographers who objectively may need more resolution, and who know how to handle it, would hardly read this article.

Given the fact that the resolution of more or less serious cameras today averages about two dozen megapixels and continues to grow, I consider further discussions on this topic simply unnecessary. The number of megapixels is no longer the parameter that you should seriously pay attention to when choosing a camera.

Thank you for your attention!

Vasily A.

post scriptum

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