Wiki Machine Vision
This list describes the most used terms in machine vision regarding machine vision cameras.
- Bandwidth: The bandwidth is the amount of data which can be simultaneously transmitted over a certain connection during a certain period. The higher the bandwidth of a connection, the more and faster the data can be received or sent. Bandwidth is defined as the amount of Megabit or Megabyte that can be transmitted per second. Typical values for Bandwidth are 40 Megabyte/second (USB2 connection), 100 Megabyte/second (GigE connection) and 400 Megabyte/second (USB3 connection).
- Bayer pattern: A Bayer pattern, also called Bayer filter is an ordinary square raster of color filters for red, green and blue (RGB) which is used for digital image sensors in vision cameras and consumer cameras. The pattern is named after the inventor Bryce E. Bayer from Eastman Kodak. Every color pixel has a RGB value, where the values of the surrounding pixels are used to generate the RGB value of a single pixel. The decoding of the Bayer pattern is called de-Bayering.
- Bit Depth: Bit depth is a measurement used to indicate the number of bits used to code the color / gray value of a pixel. The higher the bit depth is, the more values can be coded. A monochrome image in theory only needs a bit depth of 1 bit. However, it can only use the color black and white, no grey values. A normal monochrome picture therefore normally uses 8 bits and can hereby have 256 different shades. A color picture needs between 8 and 24 bits, depending on the quality of the image. With a higher bit depth is the image information often saved as RGB (red, green and blue), because not all different colors need to be saved in a separate table then.
- CCD: A charge-coupled device (CCD) is a chip which converts electromagnetic radiation into an electrical pulse. The chip consists of rows of capacitors connected by electronic switches. By opening and closing, these switches alternate so they can transport charges from on to the other side. The CCD chip is placed behind the lens of a machine vision camera. Whereby the incoming light is transformed into an electrical signal. Thereafter is this signal converted by a different chip into a digital signal, only existing out of ones and zeros. This data can be understood by a computer. CCD sensors are one of the most used sensors in machine vision cameras, however recently CCD sensors are replaced by CMOS sensors.
- CMOS: Complementary metal oxide semiconductor (CMOS) is the semiconductor technology which uses metal oxide field effect transistors with both a n- as p-conduction. By this complementary way of switching are circuits either connected with the positive and negative voltage supply, whilst the opposite transistor does not conduct voltage, whereby the switch barely uses current when there is no switching. Because of its low power usage, CMOS-technology is often used for image sensors. In this field it is the biggest competitor of CCD. Many of the operations that are needed for CCD afterwards, can be done on the chip itself with CMOS-chips, such as strengthening, noise reduction and interpolation. A CCD receives a charge on the end of an entire row of pixels which is then converted into voltage, with CMOS this happens with every pixel separately. The latest generation of machine vision cameras have only CMOS sensors and no CCD sensors anymore.
- Dynamic Range: The dynamic range is the ratio of the brightest light to the weakest light that can be perceived by a camera. The value is measured in dB. The higher the value in dB, the larger the difference between the brightest light and weakest light can be. The dynamic range is important when you want to capture an image of an object with a big contrast. You want the dark and bright parties both to be captured well.
- Fill Factor: The fill factor of an image sensor is the ratio of the light sensitive area from a pixel of the total area. For pixels without micro lenses is the fill factor the ratio of the photodiode area to the total pixel surface. However, the use of micro lenses increases the effective fill factor, often to a 100%, by converging light of the total pixel area to the photodiode. In another occasion the fill factor of an image can be reduced.
- Frame Grabber: A frame grabber is plugged in the PCI bus of a computer and provides the connection between the machine vision camera and the computer. The framegrabber transfers the data of the machine vision camera to the CPU of the computer. Newer interfaces like GigE, USB2, and USB3 can be used without frame grabber. These interfaces can use the standard network or USB ports of the computer, where an interface like Camera Link and Coaxpress still requires a frame grabber, making it way more expensive.
- Frame Rate: The number of frames per second is a measurement which indicates how fast a device captures frames or how fast it processes these frames. The term is often used in films, computer graphics, cameras, and displays. The number of frames per seconds can be expressed in frames per second or in hertz (Hz).
- LUT, Gamma Correction: Gamma correction is a non-linear operation to correct a moving image’s light intensity, illumination or brightness. The amount of gamma correction does not only change brightness, but also the RGB ratio. Gamma is the contrast of proportionality between brightness of the display and the video signal.
- Global Shutter: If the images sensor is global shutter, every pixel will start its exposure and end its exposure at the same time. This requires large amounts of memory. Since the complete image can be saved in the memory after the exposure time ends, the data can be read gradually. Manufacturing global shutter sensors is a complex process and is more expensive than making rolling shutter sensors. The main benefit of global shutter sensors is that they are able to capture high-speed moving objects/ products without having distortion.Global shutter sensors can also be used in a wider range of applications.
- Image Sensor: An image sensor is the general term for an electronic component which incorporates multiple light sensitive components and is able to capture images electronically. It converts an optical image into an electronic signal. The most used image sensors are the CCD-chip and CMOS-chip. Image sensors are applied in a variance of cameras, both for video and digital photography. The sensor converts incoming light into a digital image.
- Image Sensor Format: Before purchasing a vision camera, it is of importance to know which sizes of image sensors are available. The image sensor of a camera has great influence over the quality of your images. The image sensor format is indicated in inches. It has to be noted that inches cannot be converted to real image sensor formats. This descends from the format of old television tubes. The image sensor format is needed to calculate the lens. The most used sensor formats in machine vision are: 1/4 inch, 1/3, 1/2 inch, 2/3 inch and 1 inch. For C-mount cameras the sensor format varies from 1/4 inch up to 1.1 inch.
- Image Sensor Sensitivity: The amount of light exposed which a camera can convert into electrons determines the image sensor sensitivity. This depends on pixel size and the technique that was used to make the image sensor. Traditionally CCD sensors used to be more sensitive to light than CMOS sensors. However, over the last years this has turned around. The Sony IMX sensors are very light sensitive and hereby we can recommend the Sony Pregius image sensors very much. Such as the IMX 265.
- Interface: An interface is a method whereby two systems can communicate with each other. An interface converts information from one system into understandable and recognizable information to another system. The display is a fashion of an interface between user and computer. It converts digital information from the computer into textual or graphical shape. For machine vision cameras, the interface is the type of connection between the camera and the PC. This can be GigaBit Ethernet, USB2 or USB3.
- Interlacing: Interlacing or interlaced scanning is the technique of capturing moving images on a display. With a camera, whereby the quality of the image is improved without using more bandwidth. With interlaced scanning is an image divided in two fields. The one field exists of all even lines (scanlines), and the other out of all odd lines. Alternately both fields are refreshed. By Interlacing is the amount of image information halved. So, when the whole image is drawn in one go it is called progressive scanning. When an image is compiled in two separate times it is called interlacing. Compiling two interlaced frames together can result into a “cam effect”. This is due to when using a moving image difference exist between the two frames. Two frames are then compiled which differ 1/50th of a second. This results into two different snapshots of the same image. A display needs to compensate for this matter, this is called de interlacing.
- I/O: I/o stands for input / output. Signals being received are considered as input, signals being sent are output. A vision camera has multiple I/O ports for communication. The signal is high or low. The output signal of the vision camera can for example be used to trigger a light source, sending a trigger signal to another vision camera to synchronize both cameras or sending a signal to a PLC. The input ports are for example used to trigger the camera to capture an image, or to read the status of a button that is connected to the input port.
- Machine vision: Machine vision is the ability of a computer to see, have vision.Machine vision is comparable to computer vision, but then in an industrial or practical application. A computer requires a machine vision camera to see, this camera then collects data by capturing images of a certain product, process etc. The data that must be collected is specified beforehand by the software used on the vision system. Data will be sent to a robot controller or computer after the data collection phase, which will then execute a certain function.
- Motion Blur: Motion blur is the phenomenon that objects on a photo or video image appear blurry, as a result from the movement of an object and/or the camera.Motion blur often occurs when a shutter time is used which is too long. The projected image of the object on the image sensor should not move more then half a pixel during the exposure time. To calculate the maximum exposure time we have the following example. The field of view is 1000x600mm and the Machine Vision Camera has 1000x600pixels resolution. This means 1pixel/1mm. If an object moves with 1m/second this will be 1000mm/second. Motion blur will be noticed if the object moves with more then half a pixel, that is 0,5 * 1pixel/1mm= 0.5mm. The maximum exposure time is (max object movement=0.5mm) / (object speed = 1000mm) = 0.0005seconds = 0.5ms. In this case the max exposure time to eliminate motion blur is 0.5x1000=500us.
- Pixel Binning: In image sensors the process of pixel binning refers to neighbouring pixels combining their electric charge, to change into one super-pixel, and hereby reducing the amount of pixels. This increases the signal to noise ratio (SNR). There are three kinds of pixel binning which are horizontal, vertical and full binning. Pixel binning often happens with 4 pixels (2x2) at a time. However, some image sensors are also able to combine up to 16 (4x4) pixel at the same time. Hereby the sensor increases the signal to noise ratio by 4, reducing the sample density (therefore resolution) by 4.
- Pixels: Pixels are picture points from which an image is built up. The pixel is the smallest possible element of an image. Every pixel can have a random gray / color value. Jointly the pixels form the desired image. The term pixels derived from the words picture and element and is often abbreviated as ‘px’. The number of pixels of an image is called resolution. The higher the resolution, the more pixels per millimeter, making your image sharper. Resolution is often expressed in pixels per inch (ppi). The image sensor of a machine vision camera also consist out of pixels. The number of pixels depends on the image sensor. A sensor with an image of 6000x4000pixelscontains 24 million pixels. Expressed as 24MP or 24 Mpx (megapixels). The resolution of our cameras is always mentioned in the product description.
- Progressive Scanning: Progressive scanning is the technique to display, save or pass along moving images, where a frame does not exist of multiple fields, but all rows are refreshed in order. This is the opposite of the interlaced scanning method which is used with older CCD sensors. Progressive scanning is used on all CCD sensors that are used in our machine vision cameras.
- Quantum Efficiency: Quantum efficiency refers to incident photon to converted electron (IPCE) ratio, of a photosensitive device such as the image sensor of a machine vision camera.
- Region of Interest: Region of Interest(ROI) of a machine vision camera is the area / part of the image sensor that is read-out. For example a vision camera has an image sensor with a resolution of 1280x1024pixels. You are only interested in center part of the image. You can set a ROI of 640x480 pixels inside the camera. Then, only that part of the image sensor will capture light and transmit the data. Setting a ROI in the vision camera will increase the frames per second because only a part of the image sensor will be read out, reducing the amount of data to transmit per captured image and allowing the camera to make more images per second.
- Resolution: Resolution in the area of digital image processing is a term used to describe the number of pixels of an image. The higher number of pixels, the higher the resolution is. Resolution is expressed in the amount of pixels horizontal and vertical or the total amount of pixels of a sensor, expressed in Megapixels. An image can have a resolution of 1280x1024pixels and this is also expressed as a 1,3 Megapixel resolution.
- Rolling Shutter: A rolling shutter sensor has a different method of image capturing compared to the global shutter. Namely, it exposes different lines at different times as they are being read out. Each line is being exposed in a row, each line is being fully readout before the next line is up. With a rolling shutter sensor, it requires the pixel unit only two transistors to transport an electron, reducing the amount of heat and noise. Relative to the global shutter sensor is the structure of rolling shutter simplified and therefore cheaper. The downside of the rolling shutter however is that not every line is exposed simultaneously, which will cause distortion when trying to capture moving objects.
- Shading Correction: Shading correction or flat field correction is used to correct vignetting of the lens or dust particles on the image sensor. Vignetting is darkening of the image corners when compared to the centre of the image. Using shading correction / flat field correction requires the same optical setup by which the original images have been captures during the calibration of the shading correction. So, with the same lens, diaphragm, filter, and same positioning. Also, the focus which was used when making the calibration image has to be the same.
- Shutter Time/ Exposure Time: The shutter time or exposure time is the amount of time that light falls on the sensor of the camera. Lighting and illumination are very important elements with . Your exposure time determines how much light falls on your sensor and hereby the number of details which are visible on that image. Your image can lose a lot of details with too much or too little light, because these details fall away in too dark or too bright parts of the image. Therefore, is exposure time an important element with the illumination of your images and is hereby one of the three most important elements of the exposure triangle. The exposure time not only arranges the exposure of your image, but also how focused or blurred movement in your image looks like. With a short exposure time you can capture fast movements and freeze them. With a long exposure time you can make movements look fluent.exposure time can be manually adjusted on your machine vision camera. Exposure times can vary from 5us up to a second. Really depending on the type of application you will require a long or short exposure time.
- Signal to Noise Ratio: The signal to noise ratio(SNR) is a measurement used to measure the quality of a signal in which a disturbing noise is present. The signal to noise ratio measures the power of the desired signal relative to the power of the present noise. The higher this value, the larger the difference between the signal and the noise, making it possible to retrieve weak signals better. As a result, a sensor with a high SNR value is better able to capture images in low light situations.
Reviews VA Imaging
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8Cameras are a great value for money
The cameras are a great value for money and the lenses also. The software is outdated and needs refreshing. It took me considerable amount of time to discover how to access the camera features. The cameras are a great value for money and the lenses also. The software is outdated and needs refreshing. It took me considerable amount of time to discover how to access the camera features.
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10Excellent quality material and attentive and reliable supplier
In the commercial phase we had maximum support and delivery times were respected. The material is quite good with low and competitive costs. In the commercial phase we had maximum support and delivery times were respected. The material is quite good with low and competitive costs.
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10Fast cable delivery
I had ordered a camera but forgotten to include the required cable. the cable was ordered and delivered very fast. I had ordered a camera but forgotten to include the required cable. the cable was ordered and delivered very fast.
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8Fast delivery
Fast delivery even without paying the speed premium Fast delivery even without paying the speed premium
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9Fast Delivery and good quality!
A very good company, I will continue to cooperate next time！ A very good company, I will continue to cooperate next time！
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10Fast service
Extremely fast service. I got the camera next day. Highly recommend the seller! Thank you! Extremely fast service. I got the camera next day. Highly recommend the seller! Thank you!
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8.5Good Experience
Top, good experience. Very attentive and quick to respond. Product arrived in good condition. Top, good experience. Very attentive and quick to respond. Product arrived in good condition.
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8Good quality and fast delivery
So far, all components meet expectation, it would be great, though, if 3d models for all components were available. So far, all components meet expectation, it would be great, though, if 3d models for all components were available.
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10Great customer support, products and prices
I contacted GeT Cameras to help out with selecting the best camera and lens solution for me. They provided great support. I ordered with express and received the products 2 days later :) I contacted GeT Cameras to help out with selecting the best camera and lens solution for me. They provided great support. I ordered with express and received the products 2 days later :)
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9Great prices, great service, everything great
Bought quite a few cameras from these guys, prices are great, service is great, delivery times of the hardware is also very nice. Bought quite a few cameras from these guys, prices are great, service is great, delivery times of the hardware is also very nice.
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10Great products. Excellent support.
GeT Cameras in Germany made some photo's of our products to show the performance of their cameras and they looked perfect. Recently we purchased a camera with lens, and LED lights. We are not exper... GeT Cameras in Germany made some photo's of our products to show the performance of their cameras and they looked perfect. Recently we purchased a camera with lens, and LED lights. We are not experienced with machine vision but the installation worked out fine. After installation on our laboratory we were surprised again of the high quality of the photos and the versatility of this system. (options in Galaxy viewer and integration in Python. Recently we had an issue with the software and the customer support was able to give us the relevant information to fix it within one day. The next time we need a camera we will not be looking to other suppliers but contact GeT Cameras immediately.
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10Great support and inhouse knowledge of the cameras
First I was a little bit sceptic about buying online industrial cameras. It’s a critical part for our machine. For a new product development there was a lot of price pressure. We needed a cheap cam... First I was a little bit sceptic about buying online industrial cameras. It’s a critical part for our machine. For a new product development there was a lot of price pressure. We needed a cheap camera. I called them and Caspar was providing great support. He even advised a cheaper camera than I had in mind. I was just surprised by the inhouse knowledge of get cameras about machine vision. Never expected this from a webshop. The image an built quality of the camera is also great. The camera feels and operates the same as our Basler cameras.
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10Great support by email
I ordered a 20MP USB3 camera including a lens 2 months ago for a datamatrix code reading application. In the beginning I was sceptic because of the low prices, but support by email was great. They ... I ordered a 20MP USB3 camera including a lens 2 months ago for a datamatrix code reading application. In the beginning I was sceptic because of the low prices, but support by email was great. They advise a lens and provided additional technical information. Unfortunately they don't offer a loan service, but I decided to try it. I had the cameras in house within 2 weeks and connection was easy. The SDK looks like the SDK from Basler so I felt directly comfortable with it. The camera and lens was a perfect match and now I'm able to read small DMC codes on large products with just a single camera.
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10Great support while selecting a lens
We have bought a 20MP camera and lens with extension tubes to use it as a digital microscope in our lab. The support with selecting a lens was great. Connecting the USB3 camera was easy. We receive... We have bought a 20MP camera and lens with extension tubes to use it as a digital microscope in our lab. The support with selecting a lens was great. Connecting the USB3 camera was easy. We received everything on time.
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10High quality
High quality components and service! My order was handled quickly and arrived ahead of schedule. Would recommend. High quality components and service! My order was handled quickly and arrived ahead of schedule. Would recommend.
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10It is important to have a skilled and efficient team of workers to get the goods efficiently.
Maintained a good relationship and very good communication from start to finish to purchase the item. Maintained a good relationship and very good communication from start to finish to purchase the item.
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9Outstanding products and customer service
The customer service staff was friendly, easy to approach and helped us select the appropriate products which fit our use case perfectly. The customer service staff was friendly, easy to approach and helped us select the appropriate products which fit our use case perfectly.
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10Outstanding products and customer service
Get Cameras were extremely kind to sponsor us with some amazing equipment for our RoboCup student team, Delft Mercurians. We had no issues with the cameras, they perform as advertised and enabled u... Get Cameras were extremely kind to sponsor us with some amazing equipment for our RoboCup student team, Delft Mercurians. We had no issues with the cameras, they perform as advertised and enabled us to continue with the project and the company was extremely supportive of us overall. The customer service staff was friendly, easy to approach and helped us select the appropriate products which fit our use case perfectly.
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8Perfect customer interaction
Good site and perfect customer interaction. Good site and perfect customer interaction.
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10Products delivered sooner than promised
Ordered products were delivered sooner than promised, all ordered items were included in the package and we had no problems to make them work (cameras work with the attached software and with Matlab). Ordered products were delivered sooner than promised, all ordered items were included in the package and we had no problems to make them work (cameras work with the attached software and with Matlab).
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10Professional support, fast delivery and good product.
I liked that your team helped me chose the needed equipment by my description. The items that i have ordered are exactly what i have looked for. I liked that your team helped me chose the needed equipment by my description. The items that i have ordered are exactly what i have looked for.
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10Prompt responses to many questions
Prompt responses to our many questions. A good selection of cameras despite shortages elsewhere in the industry and we have been able to specify some of these cameras to keep projects moving forwar... Prompt responses to our many questions. A good selection of cameras despite shortages elsewhere in the industry and we have been able to specify some of these cameras to keep projects moving forward. We continue to buy regularly.
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10Quick responses and good selection of cameras
Prompt responses to our many questions. A good selection of cameras despite shortages elsewhere in the industry and we have been able to specify some of these cameras to keep projects moving forwar... Prompt responses to our many questions. A good selection of cameras despite shortages elsewhere in the industry and we have been able to specify some of these cameras to keep projects moving forward. We continue to buy from Get-Cameras regularly.
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10Quick shipping and excellent customer service
The customer service is quick, friendly and helpful, shipping takes place fast and the quality of cameras and accessoires is excellent. Very useful is also the provided software, including coding e... The customer service is quick, friendly and helpful, shipping takes place fast and the quality of cameras and accessoires is excellent. Very useful is also the provided software, including coding examples to implement the cameras in our systems.
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10Quick shipping and excellent customer service
The customer service is quick, friendly and helpful, shipping takes place fast and the quality of cameras and accessoires is excellent. Very useful is also the provided software, including coding e... The customer service is quick, friendly and helpful, shipping takes place fast and the quality of cameras and accessoires is excellent. Very useful is also the provided software, including coding examples to implement the cameras in our systems.
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9Suitable product for us
We already have several of your cameras. These are for stock only. Since we are taking them into stock, that means we are happy with them. Only lead time is little bit longer. We already have several of your cameras. These are for stock only. Since we are taking them into stock, that means we are happy with them. Only lead time is little bit longer.
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10Very good value for money
The camera arrived on schedule and gives excellent images. Very good value for money. The SDK makes it very easy to acquire images into a program of my own written using C++Builder (about 2 hours p... The camera arrived on schedule and gives excellent images. Very good value for money. The SDK makes it very easy to acquire images into a program of my own written using C++Builder (about 2 hours programming).
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10Very helpful customer service
We needed a vision camera for our project very urgently. They where able to deliver it in a few days time. They responded quick to my emails also when I needed support. They send me an article how ... We needed a vision camera for our project very urgently. They where able to deliver it in a few days time. They responded quick to my emails also when I needed support. They send me an article how to quickly install the camera and set the most important parameters. it was very helpfull and within half an hour we had a good live view image. We have also ordered the lens they advised. It provides a nice and sharp image.
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