The advancing technological development of CCD and CMOS sensors enables ever finer semiconductor structures to be manufactured. In general, sensor and pixel sizes are getting smaller and smaller in order to cut more and more sensors out of a wafer. This is possible because, in addition to optimizing the noise behavior of the electronics, the sensitivity of the pixels is also improving.
Since technical limits are also reached here, it is worth comparing cameras with different sensor and pixel sizes with the same resolution, especially if…
- there is little light
- low-noise images with high image dynamics are required
- Precision measurements should be carried out
A larger sensor with larger pixels is the technically better choice in almost every case, but the price is always higher.
Sensor sizes of standard cameras
Classic image processing cameras have sensors of different sizes depending on the camera used and the resolution. Most cameras with smaller sensors are used with so-called C-mount or possibly CS-mount optics. The C-mount thread has an actual diameter of 1 inch, which is 25.4 mm and a thread pitch of 1/32 inch.
The sensors used in standard cameras are significantly smaller and range from 4 to 16 mm image diagonal. These sensor sizes are also given in inches. The 1 inch sensor has a diagonal of 16 mm.
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The inch specifications of the CCD and CMOS sensors have only one historical explanation: Until the mid-1980s, pickup tubes were used in television cameras, which were far superior to the CCD or CMOS sensors invented at the end of the 1960s.
The actual image converter of tube cameras was located in a vacuum tube made of glass, and the various recording tubes were classified according to the outer diameter of the glass bulb, among other things. The diagonal of the light-sensitive area inside the tube was of course smaller, accounting for about two-thirds of the outside diameter. Equivalent CCD sensors intended to replace the cathode ray tubes had to cover exactly this area. A CCD whose light-sensitive surface corresponds to that of a 1/2 inch tube was therefore referred to as a 1/2 inch sensor, even if this does not correspond to the real CCD sensor size.
Industrial cameras usually use 1/3" sensors with a resolution of 640 x 480 pixels, cameras with 1280 x 1024 pixels mostly 1/2". The quite popular camera resolution of 1600 x 1200 pixels often uses a slightly larger 1/1.8" sensor with the same pixel size.
In general, there is a trend in the mass camera market that the sensors are getting smaller and smaller. At the end of the 1980s, a standard VGA sensor was sometimes still 2/3" in size, but today it is only 1/3". The miniaturization is a consequence of improved production processes that allow for smaller photosensitive surfaces with (hopefully) similar performance. It allows manufacturers to produce a larger number of sensors at a lower price from one wafer. A 1/3" sensor, for example, only has about 40% of the area of a 1/2" sensor and is therefore cheaper.
Important:If you have a choice between a larger sensor and a smaller sensor on the same camera version, please go with the larger variant if you…
- For example, carry out precision measurements or the finest surface inspections with as little camera noise as possible falsifying the result.
- Plan light-critical fast applications with short exposure times.
- Use color cameras that may replace monochrome cameras and when there is little light available, as they require 3-4x more light than a comparable monochrome sensor.
Large format sensor sizes of area scan cameras or line scan cameras
Significantly larger sensors measuring several centimeters in size are used for high-resolution area or line scan cameras. The dimensions of these sensors are usually not standardized and result from the resolution and pixel size of the sensors. Everything is allowed and limited only by the budget.
A line scan camera with 2048 pixels has a line length of 10.48 mm with a pixel size of 10 µm, and with a pixel size of 14 µm the sensor is already 28.6 mm long. From a sensor diagonal of 20 mm, the C-mount lens connection can no longer be used.
These cameras usually use Nikon bayonet (F-mount) or M42 to M72 as lens mounts. Only then can high-resolution sensors with large pixels be used to build line scan cameras with up to 12k pixels or area scan cameras with up to 28 million pixels.
Pixel sizes of CCD or CMOS sensors
As a result of the miniaturization of sensors, the pixel sizes are becoming smaller and smaller. Today, sensors in consumer cameras (8 to 12 megapixels for 200 euros) usually have pixel sizes of 1.7 μm, so the light-active area per pixel is only around 3 μm2. If the lighting conditions are not optimal, this leads to extremely strong sensor noise. This is absolutely unacceptable for quality control with cameras.
Image processing cameras (C-mount) with resolutions from VGA to 2 megapixels usually have pixels from 4.6 to 6.5 μm with 10 - 15 times larger light-active areas and thus significantly better signal results. If you need images that are as noise-free as possible and precise measurement results, look for the largest possible sensor pixels, even if these cameras are more expensive!
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Pixels with an edge length of 14 or 10 μm are preferably used in line scan cameras. Due to the high line frequency of 18 Hz, for example, the maximum exposure time is 1000/18000 = 55 μs for a recorded image line. The light-active area of the pixel can never be large enough.
Full well capacity of a pixel
This specification describes how many electrons a pixel element can hold before it is completely saturated. A 5.5 µm pixel can accumulate around 20,000 electrons, a 7.4 µm pixel 40,000 electrons.
However, the larger the full-well capacitance, the better the maximum signal-to-noise ratio. Consumer cameras with pixel sizes of 1.7 μm only need about 1,000 photons for pixel saturation. When digitizing with 8, 10 or even 12 bits, other noise effects (photon noise, digitization noise, dark noise) can already assume considerable proportions, disrupt the signal and thus have an extremely negative effect on the image.
However, the larger the full-well capacitance, the better the maximum signal-to-noise ratio. Consumer cameras with pixel sizes of 1.7 μm only need about 1,000 photons for pixel saturation. When digitizing with 8, 10 or even 12 bits, other noise effects (photon noise, digitization noise, dark noise) can already assume considerable proportions, disrupt the signal and thus have an extremely negative effect on the image.
Important for image processing
- The smaller the pixels, the more light is needed to capture an image. When inspection times are short, insufficient light can easily become a problem.
- In low light, small pixels produce significantly noisier images than large pixels, and the image dynamics are reduced. Noise is disruptive to the application. Use bright lighting orLED flash controlsto have more light available!
- Many megapixels don't necessarily help. Small pixel structures requirehigh-quality optical imaging, i.e. high-resolution lenses. Otherwise there will be blurry images with many pixels, but no real structural details.
- Small camera pixels also require extremely precise mechanical alignment of the sensor, since the depth of field is significantly reduced. The tilting of a 5 μm sensor in the housing may only be half as large (+/1 15 μm with aperture = 2.8) as with pixels with a structure size of 10 μm. Therefore, look for quality suppliers, otherwise the best sensor in the camera will be in vain.
FAQs
What is pixel size and sensor size? ›
Sensor size is the size of the sensor inside a camera. Pixel size is the size of image sensor that compose image sensor. Sensor size = Pixel size (V) or (H) x Effective Pixel amount (V) or (H) ex) Pixel size: 4.4μm x 4.4μm. Effective Pixel amount : 1600 x 1200.
What does 1.4 µm pixels mean? ›A camera with 1.4 micron pixels captures twice the light (per pixel) of one with 1.0 micron pixels, calculated by comparing difference in total area. Another way of saying this is that the 1.4 micron sensor is one stop brighter. Calculating these differences becomes very easy.
How do you calculate pixel size of sensor? ›To calculate pixel size, you use the width of the sensor in millimetres divided by the image width in pixels, and multiply by 1000. Eg: 16mp Micro Four Thirds sensor, 17.3mm wide, divided by 4608, multiplied by 1000 (source).
What is more important megapixels or sensor size? ›Camera sensor size is the biggest indicator of image quality. It's also important to note that it's not the only quality indicator. More megapixels will increase detail (but also tend to decrease low light quality). A backlit sensor is also better than a sensor of the same size that's not backlit.
Is it better to have a bigger pixel size? ›Pixels are the fundamental building blocks of digital photography: they are the individual elements that capture the light to make up your image. Higher pixel-count cameras promise better resolution but it's often said that their smaller pixels result in noisier, less-clean images.
How important is pixel count in a camera? ›Megapixel resolution plays an important role in how large you can print your pictures. Because the more megapixels you have, the more detail is recorded, high-resolution cameras allow you to make larger prints or crop shots without worrying about the image's pixel structure becoming visible.
What is a good pixel size? ›A good quality print will require a resolution of 900 x 1260 pixels. For a better-quality print, use 1200 x 1680 pixels. Finally, for the best quality, you should go with 1500 x 2100 pixels. Also, keep in mind the viewing distance.
What is a good pixel per inch? ›300 Pixels Per Inch (PPI)
is recommended for high quality printing. This resolution is industry standard for print quality output because it produces a good image while keeping file sizes manageable. For very detailed graphics, you may want to increase your file resolution to 600 PPI.
Pixels per inch (PPI) refers to the number of pixels contained within each inch of a digital image. It also refers to the set number of pixels a screen can display. Generally speaking, the higher the PPI, the better the image quality. Lower resolution images contain larger pixels in fewer numbers.
What is the pixel size of 1920x1080? ›In the case of a monitor with an industry-standard Full HD 1080p resolution, this display has a resolution of 1920 x 1080. This means that the screen will have a width of 1,920 pixels while the height of the screen will be 1,080 pixels. This results in a grand total of 2,073,600 pixels on-screen.
How many pixels per inch is 1920x1080? ›
15.6” 1920 x 1080: The ppi is 141 pixels per inch.
What is a good image sensor size? ›The 35mm full-frame sensor type is the gold standard among professional photographers who want the highest-quality images. The dimensions of a 35mm sensor are typically 36×24mm.
Is 48MP better than 12MP? ›The iPhone 14 Pro/Max, when using the sensor in 12MP mode, effectively has pixels measuring 2.44 microns. That's a really significant improvement. Without pixel-binning, the 48MP sensor would – most of the time – be a downgrade.
Does sensor size really matter? ›The size of a camera's sensor determines how much light it can gather to create an image, at least in part. While it makes sense that a bigger sensor can gain more information than a smaller one, producing better images, there are major perks to a smaller sensor.
Does sensor size affect image quality? ›The larger your camera's sensor, the larger the photosites, the more resultant megapixels, which allow for a better image and a higher resolution. High resolution is important to ensure that your images are high quality even when you blow up a photo to a larger size.
Does more pixels mean more detail? ›Image resolution describes the image's level of detail – higher resolution means more image detail. In digital imaging, the resolution is often measured as a pixel count. A pixel (short for picture element) is a single point or a tiny square in a graphic image stored in an ordered rectangular grid.
Is small pixel size better? ›A small pixel size is desirable because it results in a smaller die size and/or higher spatial resolution; a large pixel size is desirable because it results in higher dynamic range and signal-to-noise ratio.
How many stuck pixels are acceptable? ›Cause. During the LCD manufacturing process, it is not uncommon for one or more subpixels to get into an unchanging state causing a bright or dead pixel. A display with 1 to 5 fixed subpixel is considered normal and within industry standards.
How many pixels should a good camera have? ›A camera with 10-20 megapixels is going to, in most cases, be more than capable of meeting all your needs. You'd be served far better by saving money on your camera and investing in better lenses.
Does sensor pixel area matter? ›Larger pixels tend to produce better image quality since the full well capacity (amount of photons the pixel can hold before clipping) is greater than smaller pixels of the same design. There's more involved in overall image quality on the sensor than the pixel size itself, but it tends to play a significant role.
What is a good pixel quality? ›
At 300 pixels per inch (which roughly translates to 300 DPI, or dots per inch, on a printing press), an image will appear sharp and crisp. These are considered to be high resolution, or high-res, images.
How many pixels per inch is too much? ›Screen resolution: In general, 90 pixels per inch and above is suitable for screen displays. Less than that, and it might be slightly pixelated for watching videos or playing games. For professional work, stick close to 110 PPI to ensure you have plenty of screen space to work on sharp details.
Why is pixels per inch important? ›Pixels per inch (PPI) is the measure of resolution in a digital image or video display. Pixels per inch (PPI) is typically used to refer to the display resolution, or pixel density, of a computer monitor or screen. The greater the pixels per inch (PPI), the greater the detail in the image or display.
How many inches is good for 1080p? ›Up to 27” or 28”, 1080p works just fine. Stretch that to 32” and your image quality will suffer too much. Everything will have a blown out, blurry feel to it. We don't recommend going that far – stay within 27” and you'll be fine.
How many pixels per inch is 4K? ›As an example, a 8K TV display with a screen size of 55 inches packs in 160 pixels per inch while the 4K resolution offers just 80 pixels per inch.
How many pixels is 1080p vs 4K? ›Full HD is just another term for 1080p or 1920x1080, and those are all ways of referring to the same resolution. By contrast, 4K has a resolution of 3840x2160. That's a lot more pixels in the overall image — totaling over 8 million pixels. As always, the higher the resolution, the sharper the picture will be.
What pixel resolution is 2560x1440? ›QHD (Quad HD) or WQHD (Wide Quad HD) is the designation for a commonly used display resolution of 2560 × 1440 pixels in a 16:9 aspect ratio. As a graphics display resolution between 1080p and 4K, Quad HD is regularly used in smartphone displays, and for computer and console gaming.
Is there a standard pixel size? ›The standard resolution for web images is 72 PPI (often called “screen resolution”). At that size, the pixels you see on the screen are all the pixels there are; an image that's 4” long at 72 PPI will take up about 4” of your monitor.
What is the best aspect ratio for 1920x1080? ›16:9. The 16:9 aspect ratio is one of the most popular aspect ratios for videos. Data gathered by Global Stats shows that the most popular screen resolution in the world is 1920 x 1080 pixels which translates to a 16:9 aspect ratio.
How many pixels is 1080p in inches? ›A High Definition TV with 1080p resolution is composed of two million pixels (1920 x 1080), while a 4K TV (aka Ultra High Definition) has over eight million pixels (3840 x 2160).
What does 300 pixels per inch mean? ›
What is PPI? PPI, or pixels per inch, is the amount of pixels that get printed (horizontally and vertically) in a 1 inch line. Therefore, a square inch of print at 300 PPI will consist of 90,000 pixels. The higher the PPI, the clearer your image will be because the pixels will be denser.
What is pixel size? ›A typical definition, such as in CSS, is that a "physical" pixel is 1⁄96 inch (0.26 mm).
What size is 1920x1080 pixels? ›The resolution 1920×1080 (1080p) is quite a bit wider than it is tall. The ratio of its width to height is 16 to 9, represented as an aspect ratio 16:9. If you're using an input resolution that is not on this list, it might still be possible to capture.
What is pixel size of an image? ›PIXEL DIMENSIONS are the horizontal and vertical measurements of an image expressed in pixels. The pixel dimensions may be determined by multiplying both the width and the height by the dpi.
Is pixel size the same as image size? ›Image size refers to the width and height of an image, in pixels. It also refers to the total number of pixels in the image, but it's really the width and height we need to care about.