4K resolution is a display or video format comprised of roughly 4,000 pixels of horizontal resolution. It is a gauge of how clearly images appear on a screen.

A 4K television typically has a resolution of 3840 pixels horizontally by 2160 pixels vertically, resulting in a total of approximately 8.3 million pixels. Though this resolution is consistent across different screen sizes in the 4K category, pixel density can vary depending on screen size.

Ultra High Definition (UHD) refers to a resolution frequently used for displays and video content. The pixel count for UHD resolution is 3840 pixels horizontally by 2160 pixels vertically, and is also referred to as 2160p or 4K resolution.

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Following this innovation, many universities researched and refined the 4K format, and in 2010 4K cameras started being produced by top media and display manufacturers. This led to the format’s wider usage and adoption, and the technology became even more popular after streaming websites like YouTube began supporting 4K resolutions.

This exposes a limitation of the traditional DoF concept: it only accounts for the total DoF and not its distribution around the focal plane, even though both may contribute to the perception of sharpness. Note how a wide angle lens provides a more gradually fading DoF behind the focal plane than in front, which is important for traditional landscape photographs.

A 50-inch television with 4K resolution has a higher pixel density than an 80-inch unit with the same resolution. The smaller television screen packs the same number of pixels into a smaller area, resulting in a sharper image.

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On the other hand, when standing in the same place and focusing on a subject at the same distance, a longer focal length lens will have a shallower depth of field (even though the pictures will frame the subject entirely differently). This is more representative of everyday use, but is an effect due to higher magnification, not focal length.

Longer focal lengths may also appear to have a shallower depth of field because they enlarge the background relative to the foreground (due to their narrower angle of view). This can make an out of focus background look even more out of focus because its blur has become enlarged. However, this is another concept entirely, since depth of field only describes the sharp region of a photo — not the blurred regions.

A different maximum circle of confusion also applies for each print size and viewing distance combination. In the earlier example of blurred dots, the circle of confusion is actually smaller than the resolution of your screen for the two dots on either side of the focal point, and so these are considered within the depth of field. Alternatively, the depth of field can be based on when the circle of confusion becomes larger than the size of your digital camera's pixels.

4K monitors have the same number of pixels as 4K televisions and cameras, but the impact of pixel count on a monitor’s display will vary based on other factors, including screen size and viewing distance. Larger monitors benefit more from higher pixel counts, as the increased resolution is more apparent.

4K-Auflösung Monitor

4K resolution has revolutionized the way we experience visual content. With their impressive pixel count, 4K displays offer unparalleled clarity and detail, bringing even the smallest elements of an image or video to life. Whether you are gauging the quality of a camera or a visual display, understanding pixel count is crucial to ensuring the best viewing experience.

4K delivers four times the pixel count that 1080p does, and offers finer details and sharper images. While 4K displays can enhance the appearance of non-4K content, opting for a 4K display ensures compatibility with newer content and avoids the need for upgrades in the future.

Since there is no critical point of transition, a more rigorous term called the "circle of confusion" is used to define how much a point needs to be blurred in order to be perceived as unsharp. When the circle of confusion becomes perceptible to our eyes, this region is said to be outside the depth of field and thus no longer "acceptably sharp." The circle of confusion above has been exaggerated for clarity; in reality this would be only a tiny fraction of the camera sensor's area.

When it comes to high definition, 4K’s exceptional clarity and stunning detail is head and shoulders above the rest. If you’ve ever wondered where that clarity comes from, or exactly how many pixels are packed into a 4K display, don't miss this article. Here, we’ll explore the secrets behind 4K and delve into the precise pixel count that fuels its visual brilliance.

Though 4K offers higher pixel density and greater resolution, 3440 x 1440 is an ultrawide format that is ideal for immersive gaming and multimedia experiences, and many games and media applications offer ultrawide support. Still, 4K content is widely available, where 3440 x 1440 content has more limited availability.

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Note how there is indeed a subtle change for the smallest focal lengths. This is a real effect, but is negligible compared to both aperture and focusing distance. Even though the total depth of field is virtually constant, the fraction of the depth of field which is in front of and behind the focus distance does change with focal length, as demonstrated below:

Note that focal length has not been listed as influencing depth of field, contrary to popular belief. Even though telephoto lenses appear to create a much shallower depth of field, this is mainly because they are often used to magnify the subject when one is unable to get closer. If the subject occupies the same fraction of the image (constant magnification) for both a telephoto and a wide angle lens, the total depth of field is virtually* constant with focal length! This would of course require you to either get much closer with a wide angle lens or much farther with a telephoto lens, as demonstrated in the following chart:

4K video is a video resolution that’s commonly used in display devices and for content creation. It offers a higher level of detail and clarity than lower-resolution formats. Its resolution is 3840 pixels horizontally by 2160 pixels vertically, which is frequently referred to as 2160p or UHD (Ultra High Definition). Multiplying these two numbers provides a total of 8,294,400 pixels.

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5K offers sharper and more detailed images due to its higher pixel density, but the difference is most noticeable on larger screens, and their displays require more powerful hardware for running applications. This advanced technology also makes them more expensive than 4K.

Another implication of the circle of confusion is the concept of depth of focus (also called the "focus spread"). It differs from depth of field because it describes the distance over which light is focused at the camera's sensor, as opposed to the subject:

Reolink has consistently pushed the boundaries of high-end security cameras by offering higher resolutions, exemplified by the 16MP model, Duo 3 PoE. This dual-lens model boasts a total of 16 million pixels, with 7680 pixels horizontally and 2160 pixels vertically. It provides nearly twice the clarity of 4K resolution. Whether for indoor or outdoor surveillance, this camera delivers effective monitoring capabilities.

In order to calculate the depth of field, one needs to first decide on an appropriate value for the maximum allowable circle of confusion. This is based on both the camera type (sensor or film size), and on the viewing distance / print size combination. Needless to say, knowing what this will be ahead of time often isn't straightforward. Try out the depth of field calculator tool to help you find this for your specific situation.

Although print size and viewing distance influence how large the circle of confusion appears to our eyes, aperture and focusing distance are the two main factors that determine how big the circle of confusion will be on your camera's sensor. Larger apertures (smaller F-stop number) and closer focusing distances produce a shallower depth of field. The following test maintains the same focus distance, but changes the aperture setting:

*Technical Note: We describe depth of field as being virtually constant because there are limiting cases where this does not hold true. For focal distances resulting in high magnification, or very near the hyperfocal distance, wide angle lenses may provide a greater DoF than telephoto lenses. On the other hand, at high magnification the traditional DoF calculation becomes inaccurate due to another factor: pupil magnification. This reduces the DoF advantage for most wide angle lenses, and increases it for telephoto and macro lenses. At the other limiting case, near the hyperfocal distance, the increase in DoF arises because the wide angle lens has a greater rear DoF, and can thus more easily attain critical sharpness at infinity.

4K-Auflösung Fernseher

When does the circle of confusion become perceptible to our eyes? An acceptably sharp circle of confusion is loosely defined as one which would go unnoticed when enlarged to a standard 8x10 inch print, and observed from a standard viewing distance of about 1 foot.

4K offers higher pixel density and sharper images than 5MP, has wider content compatibility and is suitable for video playback, gaming, and professional video editing. 5MP is most commonly used in surveillance cameras and for specific professional applications.

Pixels are the smallest units of a digital image. They each represent a single point of color or light intensity and are used to describe display resolution.

4K cameras capture images and videos at a resolution of 3840 x 2160 pixels. This is the same resolution as that provided by 4K televisions and monitors.

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By contrast, the term megapixels refers to one million individual pixels, and is used to describe the resolution or image quality of digital cameras. The megapixel quantity indicates the total number of pixels captured by the camera's image sensor, while the number of pixels determines the level of detail and sharpness in an image or video.

Depth of field refers to the range of distance that appears acceptably sharp. It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field. This tutorial is designed to give a better intuitive and technical understanding for photography, and provides a depth of field calculator to show how it varies with your camera settings.

Because 4K resolution’s increased pixel density allows for finer details and more vibrant colors, it provides visually stunning and highly detailed content and a more immersive viewing experience. Though this is especially effective on larger screens, 4K is used in a variety of applications, including television sets, computer monitors, digital cameras, video production, streaming services, and gaming.

At this viewing distance and print size, camera manufacturers assume a circle of confusion is negligible if no larger than 0.01 inches (when enlarged). As a result, camera manufacturers use the 0.01 inch standard when providing lens depth of field markers (shown below for f/22 on a 50mm lens). In reality, a person with 20/20 vision or better can distinguish features 1/3 this size, and so the circle of confusion has to be even smaller than this to achieve acceptable sharpness throughout.

Notably, the system includes advanced person, vehicle, and animal detection capabilities, enhancing its ability to discern and alert you to specific activities. The 12-channel NVR, equipped with a 2TB HDD, offers ample storage for extended footage retention.

Why not just use the smallest aperture (largest number) to achieve the best possible depth of field? Other than the fact that this may require prohibitively long shutter speeds without a camera tripod, too small of an aperture softens the image by creating a larger circle of confusion (or "Airy disk") due to an effect called diffraction — even within the plane of focus. Diffraction quickly becomes more of a limiting factor than depth of field as the aperture gets smaller. Despite their extreme depth of field, this is also why "pinhole cameras" have limited resolution.

Additionally, the intelligent Auto Tracking feature automatically follows and records moving objects, enhancing the camera's overall surveillance capabilities.

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While 8K’s delivery of four times 4K’s resolution result in sharper images with more detail, 8K displays are significantly more expensive and have limited content availability.

For macro photography (high magnification), the depth of field is actually influenced by another factor: pupil magnification. This is equal to one for lenses which are internally symmetric, although for wide angle and telephoto lenses this is greater or less than one, respectively. A greater depth of field is achieved (than would be ordinarily calculated) for a pupil magnification less than one, whereas the pupil magnification does not change the calculation when it is equal to one. The problem is that the pupil magnification is usually not provided by lens manufacturers, and one can only roughly estimate it visually.

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If you want a higher quality photographic image, choosing the higher number of pixels provided by a 4K camera is the better choice, though image quality is influenced by other factors including the quality of the camera's sensor, lens, and image processing algorithms.

While 1440p can still be appreciated on smaller screens and has the advantage of requiring less processing power and higher refresh rates that offer smoother motion, 4K provides sharper and more detailed images. 4K’s higher pixel density also provides more accurate and vivid colors. This is most noticeable at closer viewing distances.

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The key concept is this: when an object is in focus, light rays originating from that point converge at a point on the camera's sensor. If the light rays hit the sensor at slightly different locations (arriving at a disc instead of a point), then this object will be rendered as out of focus — and increasingly so depending on how far apart the light rays are.

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Note that depth of field only sets a maximum value for the circle of confusion, and does not describe what happens to regions once they become out of focus. These regions are also called "bokeh," from Japanese (pronounced bo-ké). Two images with identical depth of field may have significantly different bokeh, as this depends on the shape of the lens diaphragm. In reality, the circle of confusion is usually not actually a circle, but is only approximated as such when it is very small. When it becomes large, most lenses will render it as a polygonal shape with 5-8 sides.

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The depth of field does not abruptly change from sharp to unsharp, but instead occurs as a gradual transition. In fact, everything immediately in front of or in back of the focusing distance begins to lose sharpness — even if this is not perceived by our eyes or by the resolution of the camera.

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4K technology dates back to 1984, when the GPU ARTC HD63484 successfully created monochrome images in 4K resolution. Seventeen years after that early-stage technology, the IBM T220/T221 screen is capable of displaying 4K content was introduced.

Note: Depth of field calculations are at f/4.0 on a camera with a 1.6X crop factor,using a circle of confusion of 0.0206 mm.

4K resolution contains approximately 3840 pixels horizontally and 2160 pixels vertically. Multiplying these values delivers a total of 8,294,400 pixels, which is commonly rounded up to either 8.3 million pixels or 8.3 megapixels.

Depth of field also appears shallower for SLR cameras than for compact digital cameras, because SLR cameras require a longer focal length to achieve the same field of view (see the tutorial on digital camera sensor sizes for more on this topic).

4K resolution affects pixel count on different devices in unique ways. Below we’ll explore popular examples across various platforms.

The number of pixels per inch (PPI) varies depending on both resolution and the size of the display. PPI is a measure of pixel density and indicates how many pixels are packed into each inch of the screen. For example, the PPI calculation for a 27-inch 4K UHD monitor would be:

The number of pixels in a 55-inch display will vary based on its resolution. Common resolutions include Full HD (2.1 million pixels), 4K UHD (8.3 million pixels), and 8K UHD (33.2 million pixels). Higher resolutions will provide more detail and clarity in the displayed content.

Diagram depicting depth of focus versus camera aperture. The purple lines comprising the edge of each shaded region represent the extreme angles at which light could potentially enter the aperture. The interior of the purple shaded regions represents all other possible angles.

Yes, 2160p is commonly referred to as 4K resolution. The "2160" in 2160p represents the number of vertical pixels. In the context of video and display resolutions, "4K" generally refers to a horizontal pixel count of approximately 4000 pixels.

To understand the impact of 4K video, imagine a grid consisting of 3840 columns and 2160 rows of tiny, individual dots. These are known as pixels, and each pixel represents a single unit of color that contributes to the overall image displayed on the screen. The more pixels there are in a given area, the sharper and more detailed the image will be.